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Photovoltaic Systems: A Buyer`s Guide

1. Fuel fired generator start capability Extra relays are provided to auto start a gener ator if the batteries reach a programmed state of low 38 capacity Some can even be programmed to keep the gen erator from starting during the night to avoid the noise unless the batteries reach a second programmed low in which case the generator will start regardless 3 Grid connected capability The inverter can convert the DC output from the array to AC power that can be synchronized with the grid utility This feature makes it possible to reduce or even eliminate monthly utility bills 4 Charging capability Inverters can draw power from either the grid or a fuel fired generator to charge the battery bank while at the same time continuing to pass that power through to the electrical loads in your house Some inverters vary the charge rate and voltage to certain types of batteries and their current temperature 5 Stacking Some inverters can be linked together either to produce twice the output or to produce power that is out of phase from inverter to inverter in order to produce 240 VAC power Battery Charge Regulators Battery charge regulators control the amount of current entering the battery and protect it from overcharging and from com pletely discharging They can also measure battery voltage to detect the state of charge Regulators range from 2 to 300 A for voltages from 12 to 48 volts DC Differ
2. controller is used see the glossary on page 44 If an MPPT controller is not used further losses should be accounted for resulting in a required power capacity increase of 15 25 percent Consult your dealer Hybrid year round operation and energy requirements gt 2 5 kWh d or higher latitudes e already have a generator e very high requirements for power availability 2 4 Estimate the Required Battery Capacity ampere hours Nominal voltage of battery typically 12 24 or 48 volts Vat VDC Number of days of battery storage needed a good rule of thumb is two days for a hybrid system and three days for an autonomous system days Battery capacity Ah Total daily load Wh d x days of storage Battery voltage Vpat x 0 42 Wh dx days V x 0 42 Ah The factor 0 42 assumes an 85 percent battery efficiency and a 50 percent maximum depth of discharge If the battery is used at temperatures lower than 25 C its capacity ampere hours will decrease Consult your PV system supplier Appendix Typical Loads Typical Power Ratings of Some Common Appliances Power Rating watt 12 V DC loads Auto stereo CB radio Receive Transmit Digital clock LED Coffee maker 1 Drill s inch 1 Lighting Incandescent Compact fluorescent Four foot type double ended Portable Black and white Colour Vent fan 15 cm blade Water pump 50 3 Hair dryer 4 About
3. portable TV may be as low as 5 W but it will still require 120 Wh d 5 W x 24 h This represents the same amount of energy as using this TV 60 W for two hours a day 120 Wh d 25 Power Energy The following two terms are used to characterize electricity usage e the power or instantaneous power required and e the energy or energy consumption over a period of time Power The power you need the wattage is the instantaneous intensity of electricity that is required to power the appliances you use The more appliances used at the same time the more power required Power is expressed in watts W A watt is a convenient SI unit in electricity because it is simply the product of the current in amperes A and the voltage in volts V IW 1Ax1V This simple formula indicates for example that a 12 W compact fluorescent light will require 1 A when connected to a 12 VDC volt direct current power source Energy Energy depends not only on the power required by your appliances but also on how long and how often you use them Energy is expressed in watt hours Wh for a given period of time per day month or year It is defined as the power times the number of hours the equipment is used over this time 1Wh 1W For example using a 1650 W hair dryer for eight minutes draws the same amount of energy as using five efficient lights 11 W each for four hours about the amount that o
4. where concentrated solar energy is used to produce steam that activates a turbine connected to an electric genera tor PV power systems do not have any moving parts They are reliable require little mainte nance and generate no noise or pollutants PV systems are modular the building blocks modules come in a wide range of power capabilities from a fraction of a watt e g solar watches and pocket calculators to more that 300 W Modules can be connected to achieve the power that your application requires Some demonstration PV power plants have several megawatts of power although most installed PV systems are much smaller How Does It Work PV cells are normally fabricated using special semiconductor materials that allow electrons which are energized when the material is exposed to sunlight to be freed from their atoms Once freed they can move through the material and carry an electric current The current flows in one direction like a battery and thus the electricity generated is termed direct current DC PV Cells Modules ot oe gg ae a oe A For applications that require electricity during overcast periods batteries ensure that the PV system is autonomous The energy generated by modules can be used immediately or stored in batteries for later use Normally the excess energy generated in autonomous PV systems during sunny periods is stored in batterie
5. Housing the Batteries Your choice of battery location should comply with the Canadian Electrical Code whether you install the batteries inside or out side The location should also be designed to keep the batteries warm 25 C is best because their capacity decreases at temperatures below 25 C This means that if you choose to locate your batter ies in an unheated space you will need to insulate the area properly You will also need greater battery capacity to compensate for the losses at lower temperatures Make sure that your supplier knows about the planned location of your batteries The batteries and other equip ment should be accessible for maintenance and inspection but safety must also be considered Batteries may give off hydrogen gas during charging and can be a source of electric shock so the room or area where they are housed should be properly vented to the outside and kept locked In addition other electrical components which can also be a source of spark should be kept separately from the battery hous ing Do not locate batteries near sources of heat or possible sources of open flame or spark Finally read all of the manufacturer s recommendations and warnings about the safe and proper use and handling of batteries Inside Locations Batteries located inside the living space should be properly vented to the outside For small cottage systems with for example two 12 VDC volt direct curre
6. a significant impact on daily energy consumption The resort s electrical generating system consisted of two diesel generators a 7 5 kKW main genera tor running 24 hours a day and 3 0 kW backup generator The high cost of diesel prompted the owners to investigate a solar diesel hybrid system In 1986 the owners installed a hybrid system that included the following 564 W PV array bank of 24 two volt deep cycle batteries and e the existing 7 5 kW diesel generator The resort s diesel consumption has been considerably reduced since the PV diesel hybrid system was installed The generator is used once every three or four days for about 10 hours to recharge the batteries Previously it had con sumed fuel continuously while supplying only about one quarter of its nominal capacity The PV panels contribute about 15 percent of the lodge s energy require ments They also permit a gentle trickle charge of the batteries at effective simple and reliable During periods of little sunshine the use of the diesel generator can be reduced by drawing power from a bank of batteries and by running the generator only when the batteries are low the end of the charging cycle thereby extending battery life and increasing the system s efficiency Because the diesel generator is used more efficiently in the hybrid system configuration than it would be on its own it needs fewer oil changes and less frequen
7. au 199 kWh Uses least energy Consomme le moins d nergie Similar modals comparnad Model number 0000 1032 kWh Uses most energy Consomme le plus d nergie Standard Ordinaire wosaes similaires compares Murn ra du modele Of fes Vel i an thee 12 361 Enjoi pHa pedet acu au ure LC 1989 en 351 A EnerGuide labels provide energy consumption ratings in kilowatt hours per year for major home appliances Always keep in mind that your energy requirement has a direct impact on the following e the area of PV modules needed to power the load or recharge the batteries capacity of the batteries required to meet your needs without running a generator at night or on cloudy days and e the amount of fuel used by a generator or the size of a wind generator Watch Out For Phantom Loads A growing number of elec tronic appliances draw power even when they are turned off Examples are a TV or VCR that maintains program memory runs its clock and keeps the remote control receiver active The stand by power required can appear to be negligible and it is often not even mentioned in appli ance owner s manuals But it may represent a substantial amount of energy because power is drawn 24 hours a day For example the stand by power for a remote controlled
8. e How much power wattage and or energy watt hours per day is required e What is the energy usage pattern e g hour per day days per week seasonal use Do I need battery storage e Dolwant an autonomous hybrid or grid connected system e DoI want to start small and add modules in the future A first step in any design or cost evaluation is to assess your load i e what do you expect the PV system to power Section 6 Estimating Your Needs page 24 is intended to help you evalu ate the options worksheet is provided in Appendix A page 40 to help you estimate and choose a suitable PV system This work sheet is intended to guide you in estimating your power and energy needs evaluating the PV array size and estimating the battery capacity that you require Note that this exercise is optional However you should at least prepare a list of all appliances and other electrical equipment that the PV system might power and estimate their time of use see Step 1 in the worksheet provided in Appendix A The more detailed and accurate the list the easier the sizing of your PV system will be for you or your dealer Where to Find PV Systems Apart from some specific con sumer products or special sales PV power systems are just begin ning to be widely available in hardware or department store chains Dealers of recreational vehicles boats and electric fences may sometimes offer PV solutions adap
9. load DC loads adjusted AC loads 4803 Wh d 33 Worksheet The Wongs Year Round Residence Step 2 Make a Rough Evaluation of PV System Size 2 1 Evaluate Which Stand Alone System Is More Suitable Autonomous or Hybrid This summer cottage will be equipped with a hybrid PV system Autonomous e seasonal use summer mainly year round operation with low energy requirements 1 kWh d or low requirements for power availability limited expensive access to the site maintenance is an issue 2 2 Estimate the Available Sunlight Sunlight 3 4 h d consult the maps on page 27 or see Learn More About Solar Energy on page 46 2 3 Estimate the Required PV Array Size W Array size W _ Total daily load Wh d Peak sunlight hours x 0 77 4803 Wh d 3 4 h d x 0 77 1835 W The factor 0 77 assumes a 90 percent battery charge regulator efficiency and 85 percent battery efficiency Based on rated power output of PV modules if an MPPT controller is used see the glossary on page 44 If an MPPT controller is not used further losses should be accounted for resulting in a required power capacity increase of 15 25 percent Consult your dealer 34 Hybrid year round operation and energy requirements gt 2 5 kWh d or higher latitudes already have a generator e very high requirements for power availability 2 4 Estimate the Required Battery Capacity
10. per day AC or DC A Rated Wattage B Hours C Watt Hours Per Day check one actual or Used A x B Appliance Load AC DC typical values Per Day AC DC gt Subtotal Wh d DC Wh d DC to AC inverter efficiency Effac ac ranges from 80 to 95 percent 0 80 to 0 95 To help you with your first calculation 0 90 has been inserted in italics Adjust the efficiency value if necessary once you have chosen the inverter for your system and have read the manufacturer s ratings Adjust AC loads for inverter losses AC load Wh d 0 90 Total daily load DC loads adjusted AC loads Wh d 40 Step 2 Make a Rough Evaluation of System Size 2 1 Evaluate Which Stand Alone System Is More Suitable Autonomous or Hybrid Autonomous seasonal use summer mainly year round operation with low energy requirements lt 1 kWh d or low requirements for power availability limited expensive access to the site e maintenance is an issue 2 2 Estimate the Available Sunlight Sunlight h d consult the maps on page 27 or see Learn More About Solar Energy on page 46 2 3 Estimate the Required PV Array Size W Array size W Total daily load Wh d Peak sunlight hours x 0 77 Wh d h d x 0 77 The factor 0 77 assumes 90 percent battery charge regulator efficiency and an 85 percent battery efficiency Based on rated power output of PV modules if an MPPT
11. state of charge of batteries on board even during extended periods of time when you are not using the equipment 13 Example 5 Photovoltaics for South Pole Expedition Explorers Bernard Voyer and Thierry Petry were the first North Americans to reach the South Pole by ski unassisted Each had to pull a 170 kg pulka a toboggan like sled over an uneven surface of stratified ice swells Sunlight was available 24 hours a day during their expedition however the usable sunlight hours per day was between two and nine hours or 5 5 hours per day on average Electricity Need The explorers used a PV system to power a satellite telephone under the extreme climatic conditions This system also served as a backup for the A Photo courtesy of Bernard Voyer lithium batteries for a video camera The PV system was designed to power Explorateur Inc the following equipment Converted to Wh per day e satellite telephone 60 W 8 min d 60 W x 8 60 8 Wh d portable computer 42 W 15 min d 42 W x 15 60 10 5 Wh d positioning system 0 5 W 24 h d 0 5 W x 24 12 Wh d e video camera 20 W 12 min d 20 W x 12 60 4 Wh d Average total daily demand 34 5 Wh d As mentioned above sunshine was usable for 5 5 hours a day on average so the team needed 6 3 W worth of PV modules 34 5 Wh d 5 5 h d daily The Power System e installed PV power 2x55 VV As 5 5 W panels are common e storage capacity Lead acid 12 V 9 Ah
12. these electricity needs park administrators chose a hybrid stand alone PV system Its advan tages over a continuously operated generator include less engine maintenance a lower need for refuelling and reduced noise A power system installed in 1996 consists of the following a 600 W solar array using eight 75 W modules 4 0 kW sine wave inverter 12 e a 38 kWh lead acid battery bank and e a 5 0 kW gasoline generator To make installation easier all electrical components were pre assembled and wired on a 1 3 m board before shipment The distributor also provided a waterproof aluminum outdoor cabinet for the batteries and power equipment It was installed directly behind the living quarters A state of charge battery display and a remote control for the inverter and generator were A Photo courtesy of Soltek Solar Energy Ltd installed on an interior wall of the building for the convenience of park staff The integrated power system is completely automated The system provides the bulk of the power to the loads with the generator available for backup In the event of poor weather or excessive loads the generator is programmed to start when the battery bank reaches 50 percent of its nominal capacity This way the batteries are charged before a potentially damaging low battery condition is reached 4 People working the field with portable computers appreciate the autonom
13. to someone who has bought a system that is similar to what you want A responsible dealer will ask you questions about your power consumption lifestyle and needs before designing your PV system If you cannot afford as many PV modules as you would like but intend to add to the system later make sure that the system designer knows this 18 The PV dealer should offer a warranty on parts and labour The warranty for PV modules can now be as much as 25 years depending on the type of mod ules and manufacturers policies Most modules will perform reliably for a longer period Check which warranties the dealer offers on the other compo nents electrical and mechanical and on the labour Moreover check on follow up service avail able from the dealer In general take the same sort of precautions when buying a PV system that you would when buying a new appliance Following is a list of items to consider in evaluating a dealer s product and service Use it when choosing a dealer e design sales experience e knowledge of energy efficiency e area of expertise e product quality e product warranty e installation service e follow up service e price Making Decision Of course cost is always impor tant in any purchase decision The economics of PV systems are often quite site specific In general conventional energy sources tend to have low initial capital costs but have high oper ating and mai
14. 5 percent battery efficiency and a 50 percent maximum depth of discharge If the battery is used at temperatures lower than 25 C its capacity ampere hours will decrease Consult your PV system supplier Example 2 Year Round Remote Residential Power System The Wongs The Wongs are a young couple who have been living beside a small lake for several years away from the electric grid They run a small handicrafts business manufacturing woven goods The Wongs use a propane generator to provide power for their home and studio But they have grown tired of constant noise and pollution increasingly high fuel bills and frequent maintenance requirements Their electrical consump tion is low despite many loads because the fridge and stove run on propane Running large loads on propane greatly reduces the up front cost of a PV system After filling out the worksheet the Wongs find that meeting their needs with an autonomous system would be too expensive They figure that they can currently afford only a small fraction of the PV panels required but they may be able to add more panels in a few years In the meantime they decide to combine their existing propane generator with PV panels to make a hybrid PV system that offers the potential to reduce the aggravation and costs linked with using a genera tor Based on their current resources this appears to be their best option Knowing this they are now in a better position to talk t
15. Electric Motors Power is often expressed in horsepower hp for motors This refers to the mechanical power output of the motor If you have information on current and voltage always use this information rather than converting hp into watts A watt W is the SI unit for power 1 hp 746 W However this may ND amp 40 44 20 20 40 20 60 24 00 00 differ from the actual electric power requirements due to the power factor of a motor in AC or othe sources of inefficiency found in any motor If you intend to power a standard AC motor with a PV system you can use the following formula to estimate your electric power requirement r 1 hp mechanical output 1 kW electrical input 42 Power Rating watt 120 V AC loads Block heater 600 Clock 2 Clothes washer excluding hot water 300 500 Front loading washer 160 Coffee maker 900 Dishwasher excluding hot water 1300 Drill 8 8 inch 300 Fan portable 115 Furnace fan motor varies greatly 350 Hair dryer 1000 1500 Curling iron 28 Iron 1000 Lighting Incandescent 25 100 Compact fluorescent 4 20 Four foot type double ended 40 Microwave oven 600 1500 Personal computer Desk model 250 Laser printer while printing standby 600 30 Laptop in use 29 Laptop charger 100 max Radio 5 Saw 400 1000 Radio telephone transmitting idle 96 12 Single side band radio idle i Stereo 30 TV 19 inches Black and white in use 60 Colour in use st
16. New production techniques led to the manufacture of multi junction amorphous cells which contain two or three layers of semicon ductor Because of the lower efficiency modules that are physically larger are needed in order to generate a given amount of power Other thin film technologies have been developed such as cadmium telluride and copper indium diselenide and are beginning to appear on the market A Monocrystalline polycrystalline and flexible amorphous silicon cells Photos courtesy of Siemens Solar Industries Photowatt International S A and United Solar Systems Corp respectively 35 The Electric Characteristics of PV Modules The Current Voltage Curve The PV module can be operated at any combination of current and voltage found on its I V curve But in reality it operates at only one combination at a given time This favoured combi nation is chosen not by the modules but rather by the elec tric characteristics of the circuit that is connected to the modules The voltage that occurs when current is zero is known as the open circuit voltage Voc On the other hand the current when the voltage is zero is referred to as the short circuit current Isc While current and voltage are at their highest under short circuit and open circuit conditions respectively the power at these points is zero In practice a system operates at a combination of current and vol
17. RENEWABLE a Photovoltaic Systems A Buyer s Guide Sg Vary 5S nw e es tim m tx Xj A SN UA ivi Natural Resources Ressources naturelles Canada Canada Canada Photovoltaic Systems Buyer s Guide This guide is distributed for information purposes only and does not necessarily reflect the views of the Government of Canada or constitute an endorsement of any commercial product or person Neither Canada nor its ministers officers employees or agents make any warranty with respect to this guide or assumes any liability arising from this guide Her Majesty the Queen in Right of Canada 2002 Cat No M92 28 2001E ISBN 0 662 31120 5 Aussi disponible en fran ais sous le titre Les syst mes photovolta ques Guide de l acheteur Table of Contents About This Guid a ee ee ee ee er eee ee re ee ee 2 1 What Is a Solar Electric or Photovoltaic PV System 3 ducal Se ee eee ee ee ey ee er Pa ee eee ee eee ee eee 3 Eloy oe coca eos Rhee eee Be die wer me dd bode Oe res hae 3 The Types oi Py Power dodo E Vac d 4b eo 3 9 93 doR uw Y P Pr P RR REY pe 4 2 What Photovoltaics Do for 7 The AdVargGages or PY Power oy qaae pcd EU HO Dean ACE Pol VE
18. RO UREA EERE DES OED HERES OR OWE 7 The lm Power Systems ied sd de do p acit ded po S Ee Rd 8 3 Photovoltaics at Work in Canada 9 uisa 5 3 TID IET IIT TIU PPM 9 PO er TOL DONDE edd dd acq d dope V uo qub Jordi s ur der B on dO 11 Mobileand Recreational 2444456 died Erde rh dert dE OCC P Doe dolce 0b dre de eee ose bead 13 UPC d QC EDD ODE ORC CR UR IDE EE CHOIR Od dd 15 APY System TO Suit Your Particular Power A dc depo AR Roe de CC REE DEES o4 ERLE 16 4 Buying Your Photovoltaic System 17 yee REM US o edd uidi GO euh Pd cde RR dU M d P PORE CORR E RH 17 DUDEN Tora E POET oes die heb bee OEE og dra Se adeundi dba anes ead 17 Aue 18 aI caus suena dur UE dca IUS vox 482 E 18 5 Installing and Maintaining Your Photovoltaic System 20 ee ee ee ee eee ee ee we ee e
19. Remote Lodges Owners of remote fishing lodges may find that a properly designed PV hybrid system is economically attractive be it PV diesel PV wind or a combination of the two The Example 3 A Solar Diesel Hybrid System at Tarryall Resort Catherine Lake Near Keewatin Ontario et d P al Tarryall Resort operates from April to October The resort consists of seven cottages and a main house that can accommodate up to a dozen people The cottages are equipped with propane powered appliances and lighting Electricity is used year round in the main lodge to power a full range of appliances including a clothes washer a large freezer a water pump televisions lights and power tools The resort is located six kilometres from the electrical grid In 1980 the owners considered connecting to the utility grid but the cost was estimated at more than 80 000 The owners instead decided to improve the resort s energy effi ciency They switched to more efficient 12 V fluorescent lights put a smaller motor in the water high cost of diesel generation at remote sites often prompts the owners to look for alternatives namely renewable energy tech nologies In many instances a PV diesel hybrid system proves attractive because it is cost pump installed timers on the exte rior lights and moved their freezer outdoors in the winter Using more efficient lights in particular has had
20. age amount of electricity needed to run this cottage is 5 5 kWh d very low by Canadian standards mainly during the sum mer The load consists of lights household appliances power tools water and pool pumps an alarm system etc This load is expected to be 75 percent less during the winter when only exterior lighting and the alarm system are active Three possible solutions were analysed the replacement of the overhead power line a submerged cable and renewable energy Due 10 to Canadian Coast Guard regula tions the new overhead line would have to be at least 10 15 m higher than the one previously installed And it would have been expensive for Hydro Qu bec to install a submerged cable given the high levels of polychlorinated biphenyls PCBs in sediments of the St Lawrence River In November 1997 Hydro Qu bec decided to evaluate alternative options A PV stand alone system was preferred to a wind generator due to the potential for low winds in the Montr al region in the summer Finally a solar only PV system was chosen because the electricity needs in the winter were about a quarter of those in the summer This would avoid the trouble of maintaining a fuel fired generator The solar only PV system consists of the following twelve 90 W PV modules with total capacity of just over 1 kW in 12 VDC volt direct current e the existing Hydro Qu bec pole used for the support structure a s
21. ampere hours Nominal voltage of battery 24 VDC typically 12 24 or 48 volts Number of days of battery storage needed a good rule of thumb is two days for a hybrid system 2d Battery capacity Ah Total daily load Wh d x days of storage Battery voltage Vpat x 0 42 4803 Wh d x 2d 24 V x 0 42 953 Ah at 24 V The factor 0 42 assumes an 85 percent battery efficiency and a 50 percent maximum depth of discharge If the battery is used at temperatures lower than 25 C its capacity ampere hours will decrease Consult your PV system supplier 8 Technical information on Photovoltaic System Components PV Technology The most common photovoltaic PV cell material is silicon It is one of the most abundant elements on earth sand from the beach is an oxide of silicon The first commercial PV cells were monocrystalline silicon Other manufacturing techniques resulted in polycrystalline silicon cells A monocrystalline cell is made of a single crystal a polycrystalline cell contains many crystals Commercial polycrystalline cells are only slightly less efficient than monocrystalline cells and are therefore widely used because their cost performance ratio is similar The development of thin film technologies reduces costs further by decreasing the amount of material needed to make a cell Amorphous silicon modules require only a thin layer of silicon and can be mass produced
22. andby with remote control 100 5 Remote control standby 5 Toaster 1100 Vacuum cleaner 200 1400 VCR on standby 30 5 Water pump 5 hp jet 1000 Note These are typical values only For exact numbers consult product literature or supplier Appendix Energy Efficient Lighting Comparison of Typical Lighting Systems Incandescent Bulbs Watts Lumens 2 221 40 495 60 855 75 1170 100 1680 Compact Fluorescent Lights CFLs with Magnetic Ballast Watts Lumens 5 220 400 9 550 13 860 18 1160 CFLs with 26 1700 Electronic Ballast Watts Lumens 15 900 18 1100 20 1200 Ks 1750 A Source Energy Efficient Lighting Products for Your Home Natural Resources Canada s pulication 43 Glossary Ampere hour Ah A current of one ampere running for one hour Autonomous system A stand alone photovoltaic PV system that has no backup gener ating source and relies only on solar energy to meet the needs of the load May or may not include storage batteries Balance of system The parts of a PV system other than the PV array and batteries This may include switches con trols meters power conditioning equipment trackers and a sup porting structure for the PV array Easement An oral or written legal agreement defining an interest in exclusive common or bipartisan use of pri vate property or air space above that property A common form of easem
23. arly Uses for PV in Commercial Applications used PV power systems early on for remote telecommunica tions repeater stations beacons and navigational aid systems Their expectations for reliability helped the PV industry develop quality products and improve design tools Small PV lighting packages are available from dealers For ski hills lighthouses isolated stretches of highway and off grid communities and businesses A The limited power needs of remote monitoring systems are easily met by A Due to the remoteness small PV systems PV powered lighting provides of repeater stations This example j j telecommunications shows a gas a practical affordable solution has been one of the wellhead first and remains one of the most popu lar applications to remote lighting problems for PV systems The Canadian Coast Photo courtesy of Guard has been using Northwestel Inc thousands of PV powered buoys along coasts for many years 16 4 Buying Your Photovoltaic System Be Prepared Before approaching a dealer you should consider your power requirements and the type of photovoltaic PV system that will suit your needs and your budget The following are typical questions that you should ask yourself Be prepared to supply the following information as precisely and clearly as possible e What is the application e What needs to be powered e Are my loads as efficient as possible
24. ction as a single electricity producing unit The modules are assembled as a discrete structure with a common support or mounting In smaller systems an array can consist of two modules plus a support structure or mounting Photovoltaic PV cell A device that converts light directly into electricity The building block of a PV module Photovoltaic PV module A number of PV cells electrically interconnected in either series or parallel and mounted together usually in a sealed unit of conve nient size to make shipping handling and assembly into arrays easier Photovoltaic PV system A complete set of components for converting sunlight into electric ity by the PV process including the array and balance of system components Power conditioning equipment Electrical equipment used to con vert power from a PV array into a form suitable for subsequent use A collective term for inverter converter battery charge regula tor and blocking diode Restrictive covenant A specialized type of easement that can be used to protect access to sunlight or wind flow for solar or wind energy applications See also Easement Series connection A method of interconnecting devices that generate or use elec tricity so that the voltage but not the current is additive Opposite of parallel connection see entry Short circuit current The current flowing freely from a PV cell through an external circuit that
25. ctric Fencing PV powered electric fencing is popular in Canada s western provinces chiefly in northern pastures where land is open for cattle Several cattle ranchers in northern Alberta and British Columbia have installed PV mod ules to charge the batteries of standard electric fencing These batteries will never run down PV powered electric fencing not only eliminates the cost and inconvenience of regular visits to check batteries but also costs less than barbed wire fencing which is the other alternative to con ventionally powered electric fencing More and more ranchers and x s 17 E E iL Jr F 7257 5 PV powered electric fencing saves both time and money for ranchers and farmers Photo courtesy of the Agricultural Technology Centre formerly the Alberta Farm Machinery Research Centre farmers in Canada are finding that PV systems which can run all summer with no need for ser vicing are a practical alternative for their remote fencing needs Water Pumping for Stock Watering and Irrigation Water pumping is one of the most attractive uses for PV sys tems In agriculture the demand for water is greatest when the e o P Tar buy ct weather is hot and dry precisely when the most solar energy is available Simple non storage types of PV systems are ideal for many irrigation applications where crops can do without water when the sun is not shining In s
26. ditioner w Autonomous or in periods of low solar radia tion Alternatively they may power the application entirely with no need for batteries e g water pumping In general autonomous PV systems are the most cost effective source of electrical power You may however decide to choose a hybrid PV system because of the environment in which it will operate or because you need a system that operates independently and reliably Hybrid PV System Generator k Power Conditioner Battery Bank A Hybrid PV system with batteries Hybrid Hybrid systems also used in stand alone systems consist of PV modules and a wind and or fuel fired generator A hybrid system is a good option for larger systems that need a steady power supply when there is not enough sun at certain times of the year or if you want to lower your capital invest ment in PV modules and storage batteries Grid Connected Grid connected PV power systems are part of the movement toward a decentralized electrical network Power is generated closer to where it is needed not solely by central power stations and major hydro stations Over time such systems will reduce the need to increase the capacity of trans portation and distribution lines A grid connected system gener ates its own electricity and feeds its excess power into the utility grid for later use This does away with buying and mainta
27. ducts services climate products climate data e ctm Some data is available directly on line at http www msc smc ec gc ca climate climate normals index e cfm You can also find some of that data in the RETScreen International software previously mentioned Reader Survey Thank you for your interest in Natural Resources Canada s NRCan s Photovoltaic Systems A Buyer s Guide In order to improve this guide we would like to ask you to take a few moments to answer the following questions 1 Where did you receive your copy of this guide Retail store Other _ Satisfactory Introductory brochure from NRCan Dealer _ Canadian Solar Industries Association Trade show 2 Did you find this publication informative Yes No 3 How much did you know about solar electric systems before reading this guide Everything A lot L A little Nothing 4 a Please rate this guide on the following attributes Excellent Good Average Easy to understand Length Clarity Completeness Photographs Graphics Format organization 4 b Please feel free to add any comments or suggestions 5 If you were to install a photovoltaic system it would be for A house A farm A cottage 6 Would y
28. e PV systems provides examples of successful Canadian installations and answers some of the ques tions you should ask yourself before approaching a PV dealer as well as questions a dealer should be able to answer Each section of this guide is divided into short easy to read subsections This format allows you to browse by topic or read the guide from cover to cover Several forms are included to help you estimate your power and energy needs Once you have read this guide you should know enough about PV systems to consult dealers and with them evaluate the best PV configuration to meet your needs now and for the future This guide provides only estimates and is not intended to replace the technical expertise required for the detailed design and installa tion of a PV system Nowhere should you construe that this guide recommends or promotes any specific products 1 What Is a Solar Electric or Photovoltaic PV System What Is PV The term photovoltaic com monly referred to as PV is derived from a combination of photo the Greek word for light and Volta the name of the Italian physicist Alessandro Volta who invented the chemical battery in 1800 The PV effect is the direct conversion of solar energy into electricity This process does not generate heat like solar domestic hot water or solar pool heating systems do It also differs from the process used in solar thermal power plants
29. e Sainte Catherine Ouest Bureau 701 Montr al OC H3B 1A7 Tel 514 392 0095 Fax 514 392 0952 Web site http www esq qc ca 46 To order more copies of this pub lication or others on renewable energy and energy efficiency call 800 387 2000 toll free You can also obtain a copy of this publica tion by visiting Natural Resources Canada s NRCan s Canadian Renewable Energy Network CanREN Web site at http www canren gc ca Free Software to Help You in Your Decision About Medium and Large Projects Renewable energy technologies such as photovoltaic systems wind farms solar ventilation air heating or solar water heating systems can be a smart invest ment RETScreen International just made it easier RETScreen International is a standardized renewable energy project analysis software program that will help you determine whether a photovoltaic system is a good investment for you The software uses Microsoft Excel spreadsheets and comes with a comprehensive user s manual and supporting databases to help your evaluation You can download the software and user manual free of charge from the Web site at http retscreen gc ca or call NRCan at 450 652 4621 or fax your request to 450 652 5177 Weather and Solar Radiation Data Monthly climate data and 1961 1990 normals are available on CD ROM To order your copy visit Environment Canada s Web site at http www msc smc ec gc ca climate pro
30. e include switches between all components of the system that need to be isolated for any reason Mounting the PV Array PV modules are designed to be installed outdoors without addi tional protection A mounting structure must be constructed to support the modules in all weather conditions Many manufacturers sell support frames designed to hold their modules you may decide to build your own Factors to be considered in mount ing the array include orientation safety structural integrity and local codes The PV array should be mounted so as to take full advantage of the sunlight In the northern hemisphere it should face south true south is best but a deviation of 15 degrees east or west will not affect performance very much Very large installations can be mounted to track the sun either automatically or manually see Technical Information on Photovoltaic System Components on page 35 In most cases the mounting is fixed at one angle a right angle to the sun at noon but can be adjusted according to the season Spring and Fall A Array orientations showing suggested tilt angles for summer spring and fall and winter use in southern Canada Select a site where the array will not be shaded at any point during the day A shadow on the array can substantially cut power output If possible ask your neigh bours if they plan to add trees or buildings adjacent to your prop erty Easements and restricti
31. ed many times without harm and are less affected by temperature changes than lead acid batteries Ni Cd batteries are more expensive and very expensive to recycle As a result their use is primarily restricted to applications where their increased reliability and low maintenance are worth the premium price Battery storage capacity is gener ally rated in ampere hours Ah This is the amount of current that a battery will deliver over a given number of hours at its normal voltage and at a temperature of 25 C The rated capacity of any battery drops with temperature The size of battery you require is determined by the total antici pated drain on the battery You can calculate this if you know the following information the volt age of the battery the wattage of the load the length of time the load is operated and the ambient temperature of the batteries For example to run a 25 W bulb for eight hours from a 12 V battery that is maintained at 25 C you would need a battery with a capac ity of at least 16 7 Ah 200 Wh at 12 V If the battery must operate at temperatures as low as Technical Note Selecting Batteries for PV Systems Points to Consider voltage and current characteristics e storage capacity is quoted at a certain discharge rate If the discharge rate the rate at which power is being drawn out is less than what the manufacturer quotes the battery s capacity is greater The opposite is als
32. ems A large portion of the cost of a grid connected PV system is manufacturing the PV modules themselves Significant decreases in manufacturing costs have occurred in recent years with further decreases expected in the future This kind of PV system is thus becoming more affordable In some urban areas in warm cli mates the cost per kilowatt hour of electricity from grid connected PV systems is competitive with that of other electricity generating systems In areas with less solar radiation the cost effectiveness of this type of PV system is still marginal But there is a potential for peak power savings in areas where air conditioning causes a power peak in the summer There are also system savings where the PV modules can replace the traditional roofing materials for buildings or the cladding material that is normally used in building facades These material savings are making the costs per kilowatt hour from grid connected PV systems increasingly competitive Decentralized small home systems also hold some potential for grid connected PV systems but the costs will have to be reduced further in order to compete with the low electricity rates now avail able in most parts of Canada Note however that PV electricity is green energy and as such is worth a premium Even though this value is subjective it should be expressed in numbers by the PV system s designer For exam ple how much is the avoided poll
33. ent is the concept of right of way as when an electric util ity has the right of way to extend electrical transmission lines across private property See also Restrictive covenant Horsepower hp An imperial system unit of power equivalent to 746 W Hybrid PV system A PV system that includes other sources of electricity generation such as a wind or diesel generator 44 Kilowatt kW One thousand watts Kilowatt hour kWh One kilowatt acting over one hour Load Anything in an electrical circuit which when the circuit is turned on draws power from that circuit lights appliances tools pumps etc Lumen A metric measurement of the rate at which light is emitted from a source Maximum power point tracker MPPT Charge controller that continu ously tracks the maximum power point MPP of a PV module or array thus increasing its effi ciency The MPP is the point on a current voltage I V curve where a PV device produces maximum power Open circuit voltage The voltage across a PV cell in full sunlight when there is no current flowing the highest possible voltage Parallel connection A method of interconnecting two or more devices that generate or use electricity such that the volt age produced or required is not increased but the current is the sum of the two Opposite of series connection see entry Photovoltaic PV array An interconnected system of PV modules that fun
34. ent types of controllers exist the on off and the pulse width modulation controls are the most common types More sophisticated controllers are more efficient but you and your dealer should evaluate whether their performance justifies the investment For example some pros and cons of manual and automatic trackers that are currently on the market When considering the use of a tracker remember that it will not significantly increase the perfor mance of the PV system during the winter in Canada The use of a tracker is more cost effective for controllers include a maximum power point tracker MPPT feature It allows a PV module or array to work at its highest power point depending on solar intensity even if the battery is recharged at a constant voltage This feature provides about 10 percent more power in the summer and roughly 30 percent more in the winter These gains are generally higher for panels with high voltage peak Vp values applications operating from the spring to the fall especially those located at higher latitude sites Because automatic trackers make the system more complex they are rarely used for applications where no one is present for extended periods of time such as telecommunications PV Trackers The sun tracks across the sky every day To get maximum out put from your PV array a tracker can be a cost effective feature The main issue is economics Does the increased output f
35. eparate ventilated outbuilding provided by the owner for the batteries and system components not always necessary 40 A solar controller 2 5 kW 120 VAC volt alternat ing current pure sine wave inverter with a surge capacity of 8 kW and e 1595 ampere hour 12 VDC battery bank The batteries offer seven day autonomy when the sun is not shining based on the expected daily load However the home owner knows about the need to monitor the use of electricity when overcast or rainy conditions are forecast Therefore a meter was installed to provide instant infor mation on the reserve capacity remaining in the battery bank based on current load consump tion and on the charge rate from the PV array Hydro Qu bec financed the instal lation of the PV system even though the cost of solar electricity produced was more than 10 times the regular cost charged by the utility about 60 per kWh versus 6 per kWh The savings on electric line maintenance justify the cost Hydro Qu bec also planned funds for replacing system components after their lifetime e g 25 years for the PV modules After two seasons of use both Hydro Qu bec and the home owner are satisfied with the performance of the PV system It can handle the heavy use of a washing machine a toaster lights pumps etc during week ends when all five bedrooms are filled by up to all 16 members of the family Power for
36. er for use during periods of low or no sunlight Certain specialized applications e g some pumping and ventilation systems and cal culators do not require storage because power is needed only during periods of light Some pumping applications use pumped water as the storage medium rather than electricity However most PV systems in Canada use batteries Your choice of battery size and type is an important design consideration particularly for systems that have no backup power source The batteries alone can represent 25 to 50 percent of total system cost so it is essential to select the right type You can use different types of rechargeable batteries depending on the sys tem s requirements Batteries with a long expected life have higher initial costs but should cost less in the long run Several batteries on the market are designed for use with renewable energy sys tems such as PV and wind systems Deep discharge marine golf cart or recreational vehicle RV batteries may also be suitable and are generally more affordable up front An experienced PV dealer can advise on what type of battery is best for your needs Most PV systems use lead acid batteries such as deep discharge lead calcium or lead antimony batteries Do not use car batteries as they are not designed for repeated deep discharges Nickel cadmium Ni Cd batteries are rarely used in residential applica tions Although they can be deeply discharg
37. erator 5 Installing and Maintaining Your Photovoltaic System One major advantage of photo voltaic PV systems is that they are relatively simple to install and maintain For large or complex systems PV companies usually help with installation and maintenance Installation Your supplier should give you any relevant system documents Carefully read all of the manufac turer s recommendations As with any electrical system safety is important You must obtain any necessary building and electrical permits and ensure that the sys tem is installed according to code Qualified people should install the system If you have a grid connected system installation will involve the local utility Wiring must be properly installed to avoid shocks fires and other hazards The main consideration is the type and size of wire For example the array wiring must be suited for outdoor use and be sized properly in order to carry the peak current As a result you will normally need larger wires for low voltage systems 12 V compared with 120 V to prevent overheating and voltage loss in the wires Consult a professional designer or installer to select the proper wires You will also need the services of a professional installer to e properly fuse the system for protection against short circuits in the wiring or appliances 20 e ensure that the system is properly grounded and pro tected against lightning and
38. ere is not enough sunlight in Canada Myth Solar electric technology is not efficient in a cold climate Example 1 A Typical Autonomous PV Application for a Remote Cottage A Photo courtesy of Cimat enr Myth Photovoltaics is not a proven technology Myth PV systems are too expensive Thousands of PV systems in myriad applications throughout Canada and millions throughout the world today have debunked these myths Although conditions in Canada pose a special chal lenge to the use of photovoltaics an appropriately designed PV system can give you reliable power to most remote sites n the following pages examples of actual cost effective PV installations across the country will demonstrate what photo voltaics can do for you A cottage located away from the power grid uses photovoltaics to power several fluorescent direct current DC lights some halogen lights and a DC water pump which supplies water to the resi dents A stove and a refrigerator run on propane fuel No inverter is needed but one can be included any time if alternating current AC loads are added The cottage is equipped with a PV system that consists of the following e two 75 W solar modules 150 W of photovoltaics e a 20 A ampere regulator load fuse panel Cottages and Residences Increasingly Canadian homeown ers are using PV systems to power lights and appliances in remote cottag
39. es and residences that are not connected to a utility grid Like these homeowners you ll appreciate the quiet low mainte nance safe and pollution free operation of a PV system as well as its versatility and reliability In general PV systems are cost competitive for cottages and residences that are more than several hundred metres from the electricity grid But they are not yet a cost competitive alternative in locations that have direct access to power from the grid e a bank of batteries and second PV system that powers a small exterior DC light with an 8 W panel and an independent battery The cottage is used primarily on weekends and during vacations which explains the large battery capacity compared with the total area of PV modules This allows more energy to be available during two days of occupancy and the PV modules recharge the batteries over the remaining five days of the week This system has been functioning maintenance free since 1997 Example 2 Autonomous PV System Powers a Summer Residence on an Island on the St Lawrence River near Montr al Quebec Major power line damages in Quebec have occurred twice in five years the most recent being the severe ice storm of 1998 For one of its customers that has an island summer cottage Hydro Qu bec decided to provide a stand alone PV system instead of maintaining a 200 m power line between the island and the mainland The aver
40. ess expensive than sim ilar DC products Consequently inverters are convenient for many systems Inverters cover a wide range of power capacity and the type needed depends on the applica tion Light duty inverters 100 1000 W are suitable for small systems e g power for lights They are available with 12 or 24 volt direct current VDC input voltages and 120 volt alternating current VAC output Larger inverters 1000 4000 W are available mainly with 12 24 and 48 VDC input and 120 or 240 VAC output For high start power surges e g from large electric motors heavy duty inverters are needed Low cost inverters produce a modified square wave which is not as good as utility power Roughly a dozen electrical loads do not run well on this type of inverter Your dealer can help you overcome most of these load problems by choosing proper appliances tools etc Sine wave inverters generally produce power that is similar to the quality of utility power Some PV modules even come with built in inverters Such mod ules are called AC modules You can build up a complete AC sys tem AC module by AC module increasing the capacity with each addition These inverters are used only for grid connected systems Many of today s inverters also come equipped with the follow ing features 1 Metering a display to provide volts input output frequency output voltage and frequency of a fuel fired generator 2
41. h low energy requirements lt 1 kWh d or low requirements for power availability limited expensive access to the site e maintenance is an issue 2 2 Estimate the Available Sunlight Sunlight 3 9 h d Consult maps on page 27 or see Learn More About Solar Energy on page 46 2 3 Estimate the Required PV Array Size W Array size W Total daily load Wh d Peak sunlight hours x 0 77 354 Wh d 3 9 h d x 0 77 118 W The factor 0 77 assumes a 90 percent battery charge regulator efficiency 85 percent battery efficiency Based on rated power output of PV modules if an MPPT controller is used see the glossary on page 44 If an MPPT controller is not used further losses should be accounted for resulting in an increased power capacity of 15 25 percent Consult your dealer 32 Hybrid year round operation and energy requirements gt 2 5 kWh d or higher latitudes already a generator e very high requirements for power availability 2 4 Estimate the Required Battery Capacity ampere hours Nominal voltage of battery typically 12 24 or 48 volts Number of days of battery storage needed a good rule of thumb is three days for an autonomous system 3d Battery capacity Ah Total daily load Wh d x days of storage Battery voltage Vpat x 0 42 354 Wh d x 3 d 12V x 0 42 211 Ahat 12 V The factor 0 42 assumes an 8
42. has no load or resistance the highest current possible Stand alone PV system A photovoltaic system not con nected to a main electric grid May be solar only or hybrid May or may not have storage batteries but most stand alone systems require batteries or some other form of storage e g water reservoir for pumping Stand off mounting Technique for mounting a PV array on a sloped roof that involves mounting the modules a short distance above the pitched roof and tilting them to the best angle Telemetry The remote measurement of any physical quantity using instruments that convert the measurement into a transmit table signal Watt hour Wh A quantity of energy One watt hour of electricity is consumed when one watt of power is used for one hour 45 Learn More About solar Energy Natural Resources Canada Renewable and Electrical Energy Division Energy Resources Branch 580 Booth Street 17th Floor Ottawa ON KIA OF4 Fax 613 995 0087 Web site http www nrcan gc ca redi or Natural Resources Canada CANMET Energy Diversification Research Laboratory 1615 Lionel Boulet Boulevard PO Box 4800 Varennes J3X 156 Fax 450 652 5177 Web site http cedrl mets nrcan gc ca Canadian Solar Industries Association CanSIA 2415 Holly Lane Suite 250 Ottawa ON KIV 7P2 Tel 613 736 9077 Fax 613 736 8938 Web site http www cansia ca nergie Solaire Qu bec 460 ru
43. hile want a system that will provide reliable power year round for their home and business Both families are inter ested in renewable energy and want to know if a PV system would be appropriate for them Example 1 Summer Cabin Power System The Smiths The Smiths own a small vacation cabin where they spend most summer weekends and holidays as well as the occasional weekend in the winter The cabin has no electricity or running water and is far from the grid After several years of filling oil lamps and hauling water the Smiths would like to enjoy the benefits of electricity However the cabin is their escape from the noise and Worksheet The Smiths Summer Cabin pollution of the city and they would prefer a quiet non polluting power source They are particularly interested in a PV system because it is durable and requires low maintenance The Smiths main priority is to keep costs at a mini mum and they are willing to sacrifice power availability to do this After all they do not have power now and the thought of the odd blackout does not bother them They have a propane powered refrigerator and they are willing to switch to fluorescent lighting and make do with a minimum of appliances to keep their power needs low For their needs a system that is small solar only and is stand alone appears to be a good solution Working through the worksheet the Smiths find that roughly a 120 W watt system and about 211 Ah a
44. ining a battery bank You can still use battery banks to provide backup power when the grid goes down but they are not required Smaller systems have a box a small grid synchronous inverter mounted on the back of each panel Larger systems have one large inverter which can handle many panels as in a stand alone system Both types convert DC power output into AC power Then they synchronize this output with the grid to slow down the electri cal meter They can even turn the meter backward If the PV output is less than the load consumption the meter slows down A Water oxygenation compressors and water pumps are examples of PV systems that function with out batteries Photo courtesy of Environergie Qu bec Inc If PV output exceeds the load consumption the meter turns backward and a credit is accumu lated This credit can be drawn out of the utility when the sun is not shining In essence the grid A Remote residences or cottages can have access to electricity without extending the grid Photo courtesy of Solener Inc acts like a limitless battery bank In most parts of Canada permis sion from the local utility is required in order to back feed power into the grid Grid Connected PV Systems E gos Meter Distributed Generation 5 Meier i dx Te S e Electric E E Centralized PX Plant i A Centralized and distributed grid connected PV syst
45. it as close as A Ensure that your PV array will not possible to the battery bank or to be shaded by neighbouring trees or the load if there are no batteries other sources of shade This will lower wiring distances and resultant power losses foundations can be posts sunk A Ground and roof mounted PV arrays into the ground to anchor the array support frame The support frame itself may be made of metal or wood Modules are mounted so that the bottom of the array is Is Magnetic South Truly South above the highest depth of snow likely to fall Make sure that there is no bottom lip on the array so that snow can slide off freely Using a compass to help you orient your PV array so that it faces south means that you will be relying on magnetic south instead of true south It is better to use true south In some parts of Canada the deviation of true south from magnetic south can be large enough to You can use pole mounting for affect the performance of your PV array If your array is fixed i e it small systems one to 12 modules will not be tracking the sun and you are unfamiliar with the devia to ensure proper orientation or to tion of the compass needle from true south at your location ask an lift them above potential sources experienced local dealer or installer for assistance of shade such as buildings or trees The main advantages are no snow buildup to shade the array and the potential to track the sun 21
46. ith a more fitting energy source such as wood or propane A solar water heater may also meet your hot water needs contact Natural Resources Canada for Solar Water Heating Systems A Buyer s Guide About Efficient Lighting For lighting consider AC or DC compact fluorescent lights instead of incandescent bulbs They give four times more light per watt of elec tricity and last 10 times longer Consult a specialized supplier for information on high efficiency lighting for outdoor applications n 60W 15W To estimate your power needs first list all the loads you want to power note whether they are AC or DC and obtain their rated wattage and the number of hours per day they will be used see Step 1 of the worksheet in Appendix A If available use the rating indicated on the label of the appliance or tool you need to power Also use the typical values given in Appendices B page 42 and C page 43 for common appliances and lighting Next for each load multiply the power rating using actual or typical values by the number of hours of estimated daily usage to obtain the total watt hours of power needed per day If con sumption is already given in watt hours per day or kilowatt hours per year as on EnerGuide labels you can skip columns A and B in Step 1 of the worksheet and simply fill in column C using the watt hours per day 10 x 1000h 10 000h A Fluorescent lights use one quarter
47. ituations where irrigation is needed independent of weather power stored in the form of pumped water rather than in costly storage batteries makes PV powered irrigation systems economically attractive Today several million hectares of remote grazing land in Canada are not being used because the costs of pumping water for stock watering by conventional meth ods outweigh the grazing benefits For many Canadian ranchers and farmers PV powered pumping systems offer a cost effective solution A stock watering using a PV powered water pumping system from a pond to prevent contamination of the source Photo courtesy of Sunmotor International PV System to Suit Your Particular Power Requirements Standardized PV systems are becoming more and more com mon However many PV systems in Canada are custom designed to take into account the particular needs of the user and the charac teristics of the site Therefore you should not necessarily expect to buy such a system off the shelf as you would a diesel or gasoline generator Rather you will probably have to consult PV equipment suppliers for a system A This PV powered aquaculture facility is on an island off Canada s west coast A A small PV module is used to power a trail indicator at night at Mont Tremblant Quebec Photo that is right for your needs courtesy of TN conseil inc The telecommunications industry and the Canadian Coast Guard E
48. l cost than any PV powered heater Also for cooking it is 1 For more information obtain a free copy of Solar Water Heating Systems Buyer s Guide from Natural Resources Canada generally more cost effective and convenient to use a stove that operates on propane or natural gas rather than solar electricity Autonomous PV powered homes and cottages often rely on wood cookstoves for cooking and space heating Refrigerators are becom ing more energy efficient so the cost of operating them with PV power is now feasible Extremely energy efficient refrigerators and freezers are unfortunately still expensive however they can be had through PV dealers From an economic point of view first consider investing in energy efficient electric appliances and then size your PV system based on actual consumption For example using compact fluores cent lights will reduce your electrical consumption for lighting by 80 percent Call 1 800 387 2000 toll free or visit the Web site at http www canren gc ca 8 3 Photovoltaics at Work in Canada The use of photovoltaic PV technology is increasing rapidly in developed and developing countries Although the Canadian PV industry has also expanded significantly over the past decade the use of photovoltaics in Canada is still relatively limited This is partly because of Canada s low utility rates but the following commonly held myths are also responsible Myth Th
49. losses in battery charging gains are greater than the cost of intend to use in your installation Effpat of 75 to 90 percent and this feature Additional losses due normally 20 W to 100 W regulator efficiency of 80 to dust or snow accumulation on to 90 percent especially if the modules are likely but they are controller does not include a relatively low Power Voltage and Current Ratings of Typical PV Modules Module Rated Power W Nominal Voltage V Nominal Current A KyoeraKC120 1200 169 7A Siemens SM100 100 17 0 34 0 2 912 08 Solarex 5 85 85 17 1 4 97 BP Solar BP 275 75 Ly 4 45 CANROM 65 65 16 5 4 2 Photowatt PWX500 50 17 2 8 UNI SOLAR US 21 21 21 1 44 Note above modules are examples of those available the market Each manufacturer provides complete line of modules that have different sizes and power ratings This list is not an endorsement of these products BESS 29 2 4 Estimate Battery Capacity for Autonomous Systems The size of battery you need depends on whether you require uninterrupted power and how much you are prepared to pay for that privilege For a weekend cabin or cottage you may not really mind if the power fails occasionally during an extended overcast period On the other hand uninterrupted power may be a necessity for some applications For most applications a good rule of thumb is to provide enough battery storage to supply power during three
50. mpere hours of batteries could meet their needs at a price they can afford Step 1 Estimate Your Power and Energy Needs watt hours per day AC or DC cece 23 Appliance Load Kitchen lights 2 Bedroom lights 2 Living room lights 2 Water pump Stereo TV black and white Subtotal A Rated Wattage actual or typical values 30 s meaz a 15 4h 2 8 120 2 Z NEN an 1 AC Wh d Hours Watt Hours Per Day Used A x ee Per Day 60 DC 354 Wh d DC to AC inverter efficiency Effac ranges from 80 to 95 percent 0 80 to 0 95 To help you with your first calculation 0 90 has been inserted in italics Adjust the efficiency figure if necessary once you have chosen the inverter for your system and have read the manufacturer s ratings The Smiths do not need an inverter because all their loads are 12 VDC volt direct current They can add one at any time Adjust AC loads for inverter losses AC load 0 Total daily load DC loads adjusted AC loads 354 Efface ac 0 90 Wh d 0 Wh d 31 Worksheet The Smiths Summer Cabin Step 2 Make a Rough Evaluation of PV System Size 2 1 Evaluate Which Stand Alone System Is More Suitable Autonomous or Hybrid This summer cottage will be equipped with an autonomous PV system Autonomous seasonal use summer mainly year round operation wit
51. ne 50 W PV module pro duces in an average day Hair dryer 1650 W x 8 60 220 Wh Fluorescent lights 5x11W x 4 220 Wh Step 2 Make Rough Evaluation of PV System Size 2 1 Evaluate Which Stand Alone System Is More Suitable Autonomous or Hybrid Stand alone PV systems can be either autonomous with or with out storage batteries relying only on solar energy or hybrid Hybrid systems combine PV with one or more other electrical generating sources and normally include storage batteries Factors that influence the type of system include the following total and peak power requirements when power is needed required power reliability whether the applica tion is seasonal or year round and whether the system will be easily accessible or installed in a remote location Autonomous Systems As the name suggests autonomous systems are self sufficient and not backed up by another generating source They normally include battery storage Some applica tions such as irrigation pumping or greenhouse ventilation require power only when the sun is shin ing Therefore an autonomous system without storage would be suitable in such cases In most cases however power is needed whether the sun is shining or not so the system includes battery storage A The autonomous PV system in Yoho National Park British Columbia supplies electricity for the amphitheatre projector and recharges the batteries of a golf cart
52. ning The PV industry like the computer industry is continually evolving Improvements in PV cells batter ies and other system components and in system design are resulting in lower prices for PV systems One of the most attractive fea tures of PV systems is that they come in modules The PV compo nent of a hybrid system can be sized to suit your budget as prices decline and or your savings increase you can add more PV panels and decrease your reliance on the backup generator If you do not already have a generator and are considering a solar only system for a cottage or sailboat you can start with a small system PV System Purchase Decision Factors Decision Factors Capital Costs Operating Costs Maintenance Costs Other Factors e g noise pollution reliability flexibility for expansion refuelling needs your time Option A Autonomous PV System System Option B Hybrid PV to power a few essential appliances and upgrade it as your finances allow Because PV systems last 25 years or more they represent a solid investment By the way the price for used panels is not much less than that for new panels because they remain in perfect condition for years The following form will help you compare the advantages and disadvantages of an autonomous or hybrid PV system with conven tional diesel gasoline or propane alternatives Option C Conventional System diesel gasoline or propane gen
53. nt bat teries you need a vent that is at least 2 5 cm 1 in in diameter Keep batteries separate from the living space by housing them in special battery cases with ventila tion to the outside For summer Heated Building a lt Battery Charge Controller Battery Shed Insulation II Battery A Battery housed in a shed cottages keep batteries full of charge to prevent freezing in the off season Outside Locations Batteries located outside of the living space should be housed in a box or shed In a very cold loca tion you can house the batteries in a buried container for better temperature control In all cases batteries should be well protected from the elements and be well vented to the outside 22 Maintenance An important advantage of PV systems is that they require little maintenance The arrays them selves are durable and reliable and need little attention The follow ing summarizes the principal maintenance that your system will need but you may wish to ask your dealer for a maintenance schedule that is adapted to your particular system and location A Unless you live in an extremely dusty area or have severe problems with ice storms you need to inspect the wiring and general panel appear ance only occasionally If your system has an adjustable mounting you can carry out this routine main tenance check at the same time as you adjust the tilt angle of
54. ntenance costs In comparison PV systems have higher initial capital costs but have lower maintenance and operating costs Thus to evaluate the economics of a PV system you must consider the total costs of competing alternatives including capital costs fuel costs and maintenance and operating costs over the life of the system For off grid commercial opera tions that have labour and maintenance costs PV systems can often be economical For individual homeowners who usually do not count their own labour for operation and maintenance as a cost of running a generator the initial cost of a PV system may appear to be high However for many home and cottage owners the non economic benefits of PV systems in particular their reliability and quiet non polluting operation far outweigh the extra costs Especially in summer owners of PV systems appreciate that they can enjoy the sounds and smells of nature without interference from their power system Of course the cost of a system depends on what it includes A simple autonomous system for a cottage or cabin suitable for pow ering a few lights a water pump and radios e g 40 100 W can cost from 700 to 2 000 Larger hybrid systems that are suitable for year round residences or lodges 200 1500 W can cost from 5 000 to 30 000 In considering the economics of PV systems it is important to realize that the costs of these sys tems are steadily decli
55. nter months in Canada provide half the hours of sunlight as in summer Much of Canada experiences high winds in the winter which can make a wind generator a logical addition to the system Fuel fired generators are then used only for backup Among other things you can use PV energy to e supply power for lights radios televisions pumps and other appliances in cottages and residences e power electric fences water pumps and other devices in agricultural operations e run water pumping and circu lation systems in game fishing and aquaculture facilities e provide reliable electric power for wilderness lodges and hunting and fishing camps e recharge or maintain charge of batteries for recreational applications such as recre ational vehicles and sailboats e power portable devices such as laptop computers e power exterior lighting e provide reliable power for many commercial applications and e lower your monthly utility bills The Advantages of PV Power Systems Users of PV power systems appreciate their quiet low maintenance pollution free safe and reliable operation as well as the degree of independence they provide Why else should you consider buying a PV system If you are some distance from an electrical grid it may be cheaper to generate your own power rather than pay to extend transmission lines from the grid Diesel gasoline or propane generators are the conventional alterna
56. nvironment Canada 200 0 200 400 600 J SU d 96 aA A Average daily number of peak sunlight hours in December use for year round operated autonomous systems Source Environment Canada 27 Hybrid Systems Hybrid systems use a combination of PV and other power sources Usually hybrid systems use a wind generator with a diesel propane or gasoline generator as backup Hybrid systems may be suited for applications such as residences and commercial build ings that are not connected to the grid If you need more than 2 5 kWh of energy per day year round and already have a generator or if you live in an area that has poor sunlight for long periods a hybrid system is probably a good choice Hybrid systems generally include battery storage the load draws power from the batteries When there is enough sunshine the PV array keeps the batteries charged If a wind generator is incorpo rated it charges the batteries during windy periods which are often when it is overcast or at night For this reason wind and solar equipment are a perfect complement to one another The diesel or gasoline generator is needed only once in a while to charge the batteries during extended overcast and calm periods The generator operates at nearly full capacity and this results in a better generator duty cycle more efficient fuel use lower maintenance costs and longer generator life Applications that involve both s
57. o a PV dealer about the type of system they want Worksheet The Wongs Year Round Residence Step 1 Estimate Your Power and Energy Needs watt hours per day AC or DC A Rated Wattage B Hours C Watt Hours Per Day check one actual or Used A x B Appliance Load AC DC typical values Per Day AC DC Fluorescent Kitchen lights 2 Living room lights 2 Bedroom lights 2 Basement bathroom and hall lights 4 Freezer very efficient Water pump Outdoor lights 2 Clothes washer front load Furnace fan Workshop lights 4 Radio in workshop SaaS SESS ESS e eee NUN ee eee ee eee ee EAS SS s s w o REESE p ER 160 10 ERE EE 1 x 4 2 ier PAs a0 i ae See ed Eu Colour TV no remote control 180 Vacuum cleaner Intermittent loads i 1000 a 1000 e g coffee maker iron small power tools block heater etc Subtotal 3999 Wh d DC 360 Wh d DC to AC inverter efficiency Effac ac ranges from 80 to 95 percent 0 80 to 0 95 To help you with your first calculation 0 90 has been inserted in italics Adjust the efficiency figure if necessary once you have chosen the inverter for your system and have read the manufacturer s ratings Adjust AC loads for inverter losses AC load 3999 Wh d 4443 Effac ac 0 90 Total daily
58. o true maximum depth of discharge different for each type of battery operating temperature range and how temperature affects performance battery lifetime the number of times the battery can be charged and discharged before it has to be replaced This number depends on the depth of discharge of cycle The less discharged the bat tery is at each cycle the more cycles it can sustain e maintenance requirements some batteries are almost maintenance free energy density the amount of usable energy a battery can produce over a given time relative to its weight and volume e cost and e warranty 37 75 2 T a v 65 o 6 9 lt v S a o N N c 30 20 10 0 10 20 30 40 Discharge Temperature C A Operating batteries at temperatures below 25 C implies that you will need more nominal capacity This will vary according to the type of batteries and rate of discharge applied 0 C then at least a 20 Ah battery would be required for the same load But in practice to protect the battery against accelerated aging a larger capacity is used to avoid a complete discharge For deep discharge batteries do not use more than 80 percent of their nominal capacity Also car batteries start to be damaged if discharged more than 20 percent of their nominal capacity there fore they are not well suited for this type
59. ocated in the far north on Ellesmere Island Nunavut is powered by a PV array on a tracker combined with a wind generator and a gasoline generator Technical Note Definition of Units Used to Describe PV System and Some Orders of Magnitude Full peak sunlight 1000 W m of energy density about the intensity of the sun at noon on a bright sunny day 1 hour of peak sunlight 1000 Wh m the equivalent of 1000 W m during one hour e g 2 h at 500 W m or 1 h at 600 W m and 2 h at 200 W m 100 W PV module Power capacity of a PV module able to produce 100 W of electricity when maintained at 25 C and exposed to full peak sunlight 1000 W m 100 W PV exposed to 1 h of peak sunlight 100 Wh of electricity Rule of thumb Typical annual radiation in Canada is 1500 h of peak sunlight range of 1100 1700 h 100 W installed potential of 150 kWh a Due to system losses and other causes of inefficiency the energy production of PV systems is often estimated as follows 100 W installed 100 kWh a 2 3 Estimate maximum power point tracker After you determine the array the Required MPPT see the glossary on page size in watts estimate the num PV Array Size 44 Typically an MPPT is used ber of modules required To do The next step is to size the PV only for medium to large systems this divide the array size by the array This takes into account when benefits related to energy power rating of the module you power
60. of application In the sizing worksheet examples in Section 7 Step 2 4 an average value of 50 percent was chosen for the depths of discharge the portion of battery nominal capacity used so that the recom mended sizes for the examples above would be 40 to 50 Ah depending on the temperature at which the battery is operated PV battery systems are usually designed to provide several days of storage in the absence of sunlight In cases where longer overcast periods are anticipated such as in the Far North it is usu ally wiser to use a hybrid system rather than trying to provide enough battery storage In this and many other cases your most practical approach may be to use a combination of backup power and batteries Power Conditioning Equipment Power conditioning equipment modifies the power from the PV array to make it more usable Two power conditioning devices inverters and battery charge regulators are described the following Inverters PV cells generate direct current DC and batteries store electric ity as DC but most common appliances require alternating current AC In cases where you need AC power an inverter is used to change low voltage DC 12 24 32 36 48 96 120 to higher voltage AC 120 or 240 Some power is lost in the conver sion as inverters average about 80 to 95 percent efficient AC wiring components and appliances are more available and generally l
61. olar and wind equipment often do not need a gas or diesel generator 2 2 Estimate the Available Sunlight Knowing the solar resources available is key to the design of an efficient and affordable PV system The maps on page 27 show the average daily values of peak sunlight hours that strike south facing fixed PV arrays in various parts of Canada in September and December These values assume that the arrays are tilted at right angles to the sun at noon Alternatively you can get weather and solar radiation values for selected sites from Environment Canada s Meteorological Service of Canada or from RETScreen International software see Learn More About Solar Energy on page 46 Choose a value for your location from either the September or December map and insert this value under Step 2 of the work sheet in Appendix A In the summer September has the fewest hours of peak sunlight Overall December has the fewest hours of peak sunlight To esti mate the available sunlight design value for a seasonal summer autonomous system use the values from the September map To estimate the available sunlight design value for a year round autonomous system use the values from the December map For a PV diesel hybrid system you may choose December values or average the two values September and December This is described in the case study on pages 33 and 34 Parks Canada s remote camp l
62. ou like to receive more information on solar electric systems 7 Would like to receive a list of dealers or installers in your area Please provide your name and address please print Name Street City Province Telephone E mail Please send the completed form to Natural Resources Canada Renewable and Electrical Energy Division 580 Booth Street 17th Floor Ottawa ON 0 4 Fax 613 995 0087 Other specify Yes Yes Postal code Poor Thank you 47
63. quire ments and then estimate the system size that your application will require a blank worksheet is provided in Appendix A page 40 Two examples have also been worked out in the next section Once you have followed this process you should be more comfortable discussing different options with a dealer If you are involved in the design of power systems a more detailed sizing and design guide called Photovoltaic Systems Design Manual is available from Natural Resources Canada see Learn More About Solar Energy on page 46 Step 1 Estimate Your Power and Energy Needs To work out how much power and energy you need you must know what loads you want to power how much power they use includ ing stand by consumption and how often they are used For sin gle purpose applications such as powering a water pump this is fairly simple to calculate However if you want a system that will run several appliances in your home or business you must estimate the usage pattern of each load The more energy you need the larger and more expensive the system especially if you want an autonomous one Therefore decrease your energy require ments as much as possible This includes using energy efficient appliances and using electricity only for appliances that really require it For example it is not practical to use a PV system to power an electric range or heating system Rather meet your heating and cooking needs w
64. rom a reduced number of tracked panels outweigh the cost of the extra panels bought for a fixed array Generally speaking the larger the array the more cost effective the tracker Remember a fixed array must be mounted on a structure so the true cost of a tracker is the difference between its cost and the cost of a fixed array mounting structure Trackers are usually mounted 3 m 10 ft off the ground avoiding the need to drill through a roof Less snow and ice accumu lates out in the open and off the ground compared with a roof Ask your dealer to explain the 39 Appendix Worksheet to Evaluate System Size This worksheet will help you geta technical design and expertise Note Figures in the equations rough estimate of the size of your required for a proper system If below must be expressed as PV system For this level of you wish to undertake such a fractions not percentages design you need only choose a technical design consider order For example an efficiency nominal battery voltage and col ing Photovoltaic Systems Design of 90 percent should be written lect the information on the Manual from Natural Resources as 0 90 in your calculations available hours of peak sunlight Canada for contact information in your area The results that you see Learn More About Solar will obtain below are only esti Energy on page 46 mates and do not replace the Step 1 Estimate Your Power and Energy Needs watt hours
65. s The batteries then provide electricity at night or when there is not enough solar radiation For these applications the number of watts in the array and the capacity of the batteries are carefully sized to give opti mum performance Some autonomous applications such as water pumping often have no need for batteries Water is pumped when the sun shines and is stored directly in a reser voir or a tank that is installed at a higher level for later use by gravity feed Other PV systems convert the electricity into alternating current AC feed excess electricity into the grid and draw out electricity at night or when the solar radia tion is low These systems are referred to as grid connected grid tied or net metered The Three Types of PV Power Systems The three typical configurations of PV power systems are autonomous hybrid and grid connected Autonomous and hybrid power systems are used in stand alone applications They are not con nected to the main utility grid and are often used in remote areas Autonomous Autonomous systems rely exclu sively on solar energy to meet a need for electricity As mentioned in the preceding they may incorporate batteries which store energy from the PV modules during the day for use at night Autonomous PV Systems PY Array a Power Conditioner Pump House Loads mor m A Autonomous PV system without batteries PV system me Power ET Con
66. t major overhauls and repairs Also the life span of the generator is extended During its first year alone savings in fuel and maintenance charges totalled about 7 000 Despite the high up front cost 36 000 in 1986 the hybrid system paid for itself within six years Tarryall s owners are pleased with their PV system and particularly enjoy the quiet clean operation a major improvement over the constant noise of a diesel generator They have since added four PV modules increasing the capacity to 752 W This further reduced the need for diesel generated electricity The original lead acid batteries were still being used in 2000 after 14 years of service Tarryall s owners were so satisfied with photovoltaics that they also equipped each of the seven cottages with an autonomous PV lighting kit one module with one deep cycle battery 11 Example 4 Hybrid PV System at the Warden Station on Huxley Island Gwaii Haanas Marine Conservation Area National Park Reserve Located in the Moresby Island archipelago in British Columbia Huxley Island serves as a registra tion office for visitors to Gwaii Haanas Marine Conservation Area National Park Reserve These include scientists visiting the area which is dedicated to environmen tal conservation The camp has a 75 2 building with a full kitchen bunks for four people and an office equipped with a satellite tele phone VHF radios and computers To meet
67. tage at which a reasonable amount of power is produced The best point is the maximum power point MPP Corresponding voltage and current are called Vp nominal voltage and Ip nominal current respectively This point of operation MPP is used to define the nominal rating and efficiency of a module 36 Maximum Power Point Pais Ip X Vp Current I Voltage V A Important points that characterize a PV module Model Serial number 123456789 Manufacturer XYZ Made in WZC Performance at 1999 W m solar irradiance and 25 C cell temperature Max power Short circuit current Rated current 48 Wp 3 35 3 02 Rated voltage Max syst open circuit voltage 600 V 19 8 V 15 9 V Open circuit voltage Fire rating Series fuse Field wiring Class C copper only 14 A WG min insulated for 75 C min AT ypical information found on a PV module label You should find all of these electric characteristics Voc Isc MPP Vp Ip on the label of a good quality PV module note that the and values are also called nominal or rated voltage and current Do not expect to get the rated power from your installed system it is impossible for a fixed system to operate at the highest power point at all times Temperature variations alone will change the amount of power your system generates Other Components in PV Systems Batteries Most off grid PV systems use batteries to store pow
68. ted to their prod ucts However for most custom applications you will need to find a PV dealer Generally this gives you the advantage of better service since such dealers should have a good understanding of the technology and can help you select size and design the system that best suits your needs There are many distributors and dealers of PV systems in Canada and the industry network is growing Some of these companies special ize in different types of systems e g communications home energy systems consumer products agricultural and unique design To find PV distributors or dealers contact the Canadian Solar Industries Association Natural Resources Canada see Learn More About Solar Energy on page 46 or consult the Yellow Pages You may also wish to obtain a referral from a satisfied customer 17 Choosing a Dealer A PV system should be designed for the best efficiency and cost effectiveness It is wise to consult a professional at the design stage Most dealers offer design and consultation services as well as PV modules and balance of system components such as batteries and inverters Some companies concentrate on industrial applica tions others specialize in residential and commercial sys tems Make certain that the dealer you select has proven experience in designing and installing the type of system you want Ask to see some systems that have already been installed or talk
69. that the staff uses to collect camping fees Photo courtesy of Sovran Energy Inc 26 In Canada about twice as much sunlight is available in summer than in winter To guarantee power year round using a solar only system a significantly larger and hence more costly array and battery system is needed Such systems are practical for applica tions in remote unattended sites which are difficult and expensive to visit and where the capital costs are rapidly offset by avoid ing costs for maintenance and fuelling visits Thus solar only systems with storage are used for electric fencing in remote areas and in communications marking and warning signs monitoring sites and other situations where reliability and low maintenance are critical Autonomous systems are also appropriate for summer vacation properties sailboats and other applications where the period of use corresponds to the period of greatest available sunlight If you consider power a luxury instead of a necessity and can tolerate the odd occasion when the system cannot meet your loads an autonomous system may be suitable at a reasonable price However if you want guaranteed power on a year round basis and can easily access the site some sort of hybrid system will likely be more affordable CANADA 200 0 200 400 600 1 KILOMETRES A Average daily number of peak sunlight hours in September use for seasonal summer autonomous systems Source E
70. the array When you adjust the angle of the array for winter operation snow loading is not a problem because the array is tilted steeply If the array becomes dusty clean it with a mild soap or plain water and a soft cloth Do not use solvents or strong detergents A Battery maintenance varies with the type used Basic maintenance includes visually checking the elec trolyte levels and regularly verifying the specific gravity of your batteries with a hydrometer Add distilled water as necessary and clean and tighten battery posts only the latter are required for maintenance free batteries Also check for any leaks or physical damage to batteries Follow battery and charge regulator instructions for annual equalization charges that help cure the batteries from plate fouling due to corrosion QOQOOOO PowerGen TN d Generator maintenance for hybrid systems is simpler and easier than using a generator to produce all your power Change the oil as recommended which will be less frequently than for a continuously operating generator A Keep track of any maintenance or modification made to the system date and action This will help you remember when your last maintenance routine was carried out and may ease troubleshooting should a problem occur 23 6 Estimating Your Needs To further investigate which kind of system will meet your power needs this section will help you estimate your energy re
71. the energy of incandescent bulbs and last 10 times longer 2 For your of Solar Water Heating Systems A Buyer s Guide call Natural Resources Canada at 1 800 387 2000 toll free or visit the Web site at http www canren gc ca 24 EnerGuide Labels If there is an EnerGuide label on your appliance you can use the electrical consumption rating in kilowatt hours per year given on the label for your worksheet Note that the EnerGuide ratings for clothes washers and dishwashers include the electricity consumed in heating the water used in those appliances These ratings are less useful to you if as we recom mend you heat your water with solar water heaters propane or wood instead of PV generated electricity If you use the value on an EnerGuide label convert the kilo watt hours per year KWh a into watt hours per day Wh d for inclusion in column C of the worksheet in Appendix A To make this conversion multiply by 1000 and then divide by 365 Finally fill in the subtotal s calculate the adjusted AC loads for inverter losses using 0 90 as your initial conversion efficiency and fill in the total daily load value at the bottom of the first side of the worksheet Smaller efficient appliances will require less PV equipment Some PV dealers also carry high efficiency appliances and lighting Canada ENER UIDE Energy consumption Consommation nerg tique 200 This moda Ca mod
72. the team needed at least two Nickel cadmium 12 V 5 Ah panels which provided extra e total weight 5 kg power to compensate for bad The conditions of operation were as follows BU vs lues eng average temperature 15 C to 33 C December January characteristics The system cost 600 Main Advantages of the PV System Another alternative would have a cold environment would be Primary lithium batteries are been to carry a small gasoline difficult The team rejected this generally used for this kind of generator The smallest lightest alternative as impractical expedition An estimated twenty generator avallable was a 300 W PV energy represented the most 10 Ah lithium batteries would have generator that weighed 18 kg economical reliable practical been needed for total cost of Apart from its weight fuel od and environmentally friendly way 6 000 and a weight of 12 5 kg have had to be carried and an to generate electricity for such an This alternative was rejected due dled Also fumes and noise from expedition not to mention to its cost and weight the generator would be unpleas the lightest ant and starting the engine in 14 Photovoltaics in Agriculture PV systems are particularly well suited where a small amount of energy in remote locations is needed for agricultural applica tions such as electric fencing water pumping for irrigation or stock watering pond aeration etc Ele
73. tives but many people find them noisy polluting and costly to run and maintain It also makes little sense to turn on 5 kW generator to power a few 100 W light bulbs PV systems reduce the negative aspects of generators by using them only as a backup When capital cost is an issue or when photovoltaics alone are not enough to replace an existing generator you can use a wind generator as part of a hybrid PV system thus reducing the use of the generator Such an intermit tent charge system is more efficient than a generator running continu ously at low load In addition to saving fuel and lowering mainte nance costs you will increase the generator s life span Also since the PV panels and battery banks are modular you can expand the PV system gradually as your budget or needs increase Limitations of Power Systems It is important to realize that PV power systems are capital inten sive from the buyer s perspective and are expensive when com pared with the low price of utility power in Canada You should therefore reserve the electric power produced by PV modules an inverter and a storage system for your most energy efficient appliances tools lights etc Although it is technically possi ble heating with photovoltaics is generally not recommended You can easily and more efficiently collect heat with a solar thermal system A solar water heater gen erates more hot water with less initia
74. to five overcast days Battery capacity for hybrid systems is usually enough for only one or two days A battery should not be completely dis charged so as not to shorten its life Thus the available capacity of a battery is less than the name plate rating A maximum depth of discharge factor is already included in the equation in the worksheet see Step 2 in Appendix A on page 41 It ensures that the battery charge never drops below 50 percent of full charge This value depends on the type of battery you select Consult your dealer Technical Note Battery Capacity Rating Watts may be expressed in Wh volts x amps Likewise energy may be expressed in Ah amperes x hours at a given voltage This is often used in the battery industry to express battery capacity For example a battery with 960 Wh of capacity is generally referred to as a 12 V 80 Ah battery 12V x 80 Ah 960 Wh Wh V x Ah 30 Use the blank worksheet to help size your stand alone PV system Now that you have estimated the size of the PV array and the amount of battery storage you require you are in a position to approach a dealer Discuss costs and make decisions on what is best for your particular situation 7 Sizing Worksheet Examples In the following examples two hypothetical case studies show how the worksheets be used The Smiths for example are interested in PV power for a remote vacation cabin The Wongs meanw
75. ution of conventional sources worth and how much is the avoided distribution cost worth A This house in Edmonton Alberta is equipped with a 2 3 system that is connected to the local power utility About 2500 kWh are produced each year The investment cost in 1995 was 28 000 To install a PV system you must pay the capital cost of the system and amortize this cost over time In contrast where there is a utility grid you pay for the electricity used and not a lump sum for the generating facility The costs of the PV system may appear to be a burden because the electricity that the system generates may cost more per kilowatt hour than what a utility charges But using a PV system may also be considered a lifestyle choice similar to choos ing between a fuel efficient car or a gas guzzling sport utility vehicle 2 What Photovoltaics Do for You Perhaps you need reliable power in a location that is not connected to an electrical grid In this case photovoltaics may be the best and most cost effective solution Many locations in Canada that have a dry continental climate have the same number of daylight hours as some Mediterranean countries A photovoltaic PV system used during the summer in Canada can take advantage of substantial daily amounts of solar energy Contrary to what many people think PV systems convert sunlight into electricity more efficiently at lower temperatures However the wi
76. ve covenants for definitions see the glossary on page 44 are two types of legal instruments When used for solar applications they provide certain guarantees to property owners about their access to sunlight If access to sunlight concerns you such a written agreement may be worthwhile Depending on the array size and For many residences and cottages the particulars of the site the PV roof mounting is an attractive array can be mounted on a roof option particularly if the building a pole or the ground In general is under construction The mod the large surface areas of the mod ules should be mounted a short ules create high wind loads on distance above the pitched roof the mounting structure so the and tilted to the optimum angle structure must be designed Since PV modules work better accordingly Due to these high when the ambient air tempera wind loads ground mounted ture is lower the free circulation installations require proper of air around them will improve foundations For small ground their performance Elevating the mounted installations array will also prevent the buildup of moisture and debris behind the modules This buildup could rot the roof and deteriorate the electrical connections For residences and cottages with a chimney the array should be mounted in such a way that shad ing from the smoke is avoided Wherever you choose to mount the array unless shading is a con cern try to locate
77. y eee ee eee eer ee eee eee ee 20 20 Ha E E E Hoes 22 ER ETT TTE TOL T T To TT TETTE 23 6 Estimating Your Needs RC a 24 Step 1 Estimate Your Power and Energy 22525 dione desi dE NE a pude E Sarda det 24 Step 2 Make a Rough Evaluation of PY System 2 2 26 7 Sizing Worksheet Examples 31 Example L Summer Cabin Power System The Smiths gx 344 Ra pad ede wee 31 Example 2 Year Round Remote Residential Power System 33 8 Technical Information on Photovoltaic System Components 35 sag pees ehh ee Rd and qa GAS mid Gee xd d EK dud Swag d 35 The Electric Characteristics of PV Modules The Current Voltage I V Curve amp scam e 9 ERE ESSERE 36 thier omg eh 4 Oe Saw eens 37 Appendix A Worksheet to Evaluate System Si
78. y that PV offers Photo courtesy of Midnight Sun Energy Ltd Mobile and Recreational Applications Chances are that you are already relying on PV technology to help you keep track of time balance your budget or enliven your leisure hours Many products such as watches calculators and toys have been PV powered in an inexpen sive reliable and convenient way for many years Equipped with tiny PV cells that produce power even in dim lighting these consumer products eliminate the need for costly batteries that need to be frequently replaced Nowadays versatile PV power packs are also used to power larger consumer products They are available in a range of sizes from fractions of a watt to over 100 W Power packs can also be hooked up in series or parallel connections to serve various power needs They can be used as either a direct power source or as a battery recharger These convenient PV systems power everything from radios cassette recorders and cameras to lawn ornaments walkway lights and batteries for sailboats and gliders The clean and noiseless opera A Many owners of recreational vehicles are already using PV technology tion of PV systems for many Photo courtesy of Rozon Batteries Inc recreational applications is a significant benefit In recreational vehicles and electric powered boats PV panels can help recharge batteries The main advantage of a PV system is that it will at the least maintain the
79. ze 40 Step 1 Estimate Your Power and Energy Needs gt SH RHEE ESTER eae AUS aed EE HE OOS DA 40 Sup 2 Make a Roush Ev luaton Ob PY Systemi oe ae dk Bede bar PG go bos dra re e RR Oo e dodo dedos 41 Appendix B Typical 5 42 Typical Power Ratings of Some Common ADDDIADOSS ud oe doe RC II eh eb ORA oo POOR UC 42 Appendix C Energy Efficient Lighting 43 Comparison or Typical Lignin Systems oe Rao mE eden cage wr a e AR qug eran EORR 43 IC CIR ge oh he T T TET rrr 44 Learn More About Solar Energy 46 Reader Survey 47 About this Guide The information in the following pages is for prospective buyers of photovoltaic PV systems for use in the following e remote cottages and residences e recreational and mobile applications e agricultural applications e remote lodges and e remote lighting applications The purpose of this guide is to help you determine whether a PV system is a suitable option for you in providing electrical power for one or more of the above uses It describes typical and innovativ

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