Presented in Electrical & Computer Engineering University of New Brunswick Fredericton, NB, Canada The Photovoltaic Cell

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1 Presented in Electrical & Computer Engineering University of New Brunswick Fredericton, NB, Canada Introduction The The concept and PVA Characteristics Modeling Operating principles Control strategies Applications Design Future

2 The need for energy Energy crisis Limited source of conventional fuel based energy Environmental issues Free source of energy Sunlight is made up of tiny packets called photons, which carry solar energy from sun to the earth.

3 We just need a device to collect and use this energy wherever we need it. Photovoltaic panels are used to collect this energy and convert it to electricity. - +

4 Photovoltaic panels consists of many solar cells, which made of semi-conductors such as Crystalline silicon and Gallium Arsenide. An individual PV cell consists of positive (P) and negative (N) type Silicones. N-type Silicon P-type Silicon proton free electron tight electron hole Ready to accept free electrons

5 P and N type Silicone layers are combined together creating a P-N junction. N-type Silicon P-type Silicon junction P-N junction acts just like in a diode so that electrons can flow in one direction only. After they are combined, N type layer becomes mostly positive as P type layer becomes mostly negative across the junction. N-type Silicon P-type Silicon junction

6 Positive protons and holes are on one side and negative electrons are on the other side. They want to be combined. But they cannot due to the electric field created across the junction. They just have to stand still until a force to push them cross the junction. - Free electron Photones are observed by the PV cell. Their energy causes the electrones to move Free electron

7 If there is a path for the electrones to flow through, they continue to move and operate the device on the path Free electron Module Types: Monocrystalline Polycrystalline Amorphous single junction Amorphous multi-junction Thin film crystalline + -

8 The power generated by a single PV cell is very small. Therefore single s with the same operating characteristics are combined in series and parallel to build up PV panels with more power. And panels are combined together to get much more power. 5 A 5 A 5 A 15 A kw

9 I-V Characteristic CURRENT (A) V A VOLTAGE (V) Isc Im I-V Characteristic P-V Characteristic CURRENT (A) POWER (W) For a certain solar irradiation and ambient temperature VOLTAGE (V) Vm Voc

10 CURRENT (A) POWER (W) VOLTAGE (V) I (A) P (W) P-V Curves P m3 I sc3 I-V Curves P m2 P m1 I sc2 Q 3 I sc1 I m1 Q 2 Q 1 S 1 < S 2 < S V m1 V 01 V (V)

11 Iph Sx Tx Io Iph: photocurrent, function of irradiation level and junction temperature Io: reverse saturation current of diode ( A). Sx Tx Iph D I 0 R sh R s I C V C e VC + RSIC IC = Iph I0 exp ( VC + RSIC) 1 ktc Rsh

12 e IC Iph I0 exp ( VC + RSIC) 1 ktc Sx Tx Iph D I 0 R s I C V C V AkT = I ln + I I R I C ph 0 C C S C e I0 Sx Tx Iph I 0 R s I C V C ( ) C = 1+ β T T TV T a x D γ C T T ( ) T TI = 1+ x a SC ( ) C = 1+ βα S S SV T S x C 1 C = 1+ S S S ( ) SI x C C VCX = CTVCSVVC I = C C I phx TI SI ph

13 V AkT = I ln + I I R I C ph 0 C C S C e I0

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15 Sx Tx + RF LF DC/DC Chopper 1 V dc =constant DC Load Bus Optional for AC/utility connection DC/DC Chopper 2 SW & RG C1 C2 PVA - C F SW2 R LS R L L L R a L a e a ω m B J T L Ipv V pv Backup Battaries Filter L LS MPPT Switchable R-L Load Constant R-L Load PMDC Motor Driving fan/pump I (A) P (W) P-V Curves P m3 I sc3 I-V Curves P m2 P m1 I sc2 I sc1 I m1 Q 3 Q 2 Q 1 S 1 < S 2 < S V m1 V 01 V (V)

16 P m 3 8 P (W) 9 P-I Curve I-V Curve I m I sc 6 I (A) 5

17 Application Schemes Stand-Alone DC Systems Stand-Alone DC and AC Systems Stand-Alone AC Systems PV-Generator Combination Utility Interface

18 Regulator DC-DC Converter PVA Backup Batteries DC LOAD DC LOAD CONTROLLER Stand-Alone DC System PVA Regulator DC Chopper DC-AC Converter (inverter) Backup Batteries DC LOAD CONTROLLER AC LOAD Stand-Alone DC and AC System

19 Regulator Boost up inverter PVA CONTROLLER Backup Batteries AC LOAD Stand-Alone AC System Regulator 3-phase inverter AC-AC interfacing units PVA Backup Batteries CONTROLLER AC Generator PV-Generator Combination

20 Regulator 3-phase inverter AC-AC interfacing units PVA Backup Batteries CONTROLLER AC Utility System Utility Interface Design Parameters Application type Location and average solar power received (W/m 2 ) Amount of power to be generated (Module type, sizing, efficiency) Installation and tilt angle (fixed or controlled) Battery backup units (Batteries and Charge regulator) Interfacing units (DC-DC, DC-AC converters, etc.) Controllers Wiring and protection

21 Typical household electrical appliances and run times. η = Generated Electrical Power Incident light power Multicrystalline silicon solar cells space-grade solar cells single crystalline silicon solar cells 33% efficiency 20% efficiency 100% efficiency Impossible 10% efficiency

22 WORKSHEET ESTIMATING THE COST OF PHOTOVOLTAIC SYSTEMS Step 1. Determine the load, available sunlight, array size, battery bank size: a. Determine the energy load required in watt-hours (Wh) per day. Multiply the number of watts the load will consume by the hours per day the load will operate. Multiply your result by 1.5. Total Wh per day required: Wh b. Determine the hours per day of available sunlight at the site. Total available sunlight: hrs/day c. Determine the PV array size needed. Divide the energy needed (1a) by the number of available sun hours per day (1b). Total array size required: Watts d. Determine the size of the battery bank (if one is desired). Multiply the load (1a) by 5 (result is watt-hours, Wh). Then divide by the battery voltage (for example, 12 volts) to get the amp-hour (Ah) rating of the battery bank. Total Battery Bank Required: Ah WORKSHEET ESTIMATING THE COST OF PHOTOVOLTAIC SYSTEMS Step 2. Calculate the cost of the PV system needed for this application: a. Multiply the size of the array (1c) by $5 per watt. Cost estimate for PV array: $ b. If a battery bank is used, multiply the size of the battery bank (1d) by $1 per amp hour. Cost estimate for battery bank: $ c. If an inverter is used, multiply the size of the array (1c) by $1 per rated watt. Cost estimate for Inverter: $ Subtotal: $ d. Multiply the subtotal above by 0.2 (20%) to cover balance of system costs (wire, fuses, switches, etc.). Cost Estimate for Balance of System: $ Total Estimated PV System Cost: $

23 Natural quartzite, Quartz sand Polysilicon % purity CZ 8 Wafers Almost free Average $40/kg Average $40 wafer $2500/kg

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25 World PV Module Shipments ( )(in Megawatts) Source: IEA Photovoltaic Power Systems Program

26 * Original source gives these individual numbers and totals them to 37,500 KW. The 2004 reported total was 30,700 KW.[ With new installations of 6,800 KW, this would give the reported 37,500 KW. Renewable Green Energy (RGE) has become popular and attractive as the energy crises occur RGE draw attention as the installation and power generation costs have dropped down RGE become important as the environmental issues are concerned. Solar PV Green energy (SPVGE) systems become a flexible power source since they can be installed almost everywhere that has sun. SPVGE systems getting more investments with reduced costs with increased efficiency.

27 U.S. Department of Energy, Energy Efficiency and Renewable Energy, Solar Energy Technologies Program. Sandia National Laboratories, Photovoltaic Systems Research & Development, Sierra Solar Systems, SECO- State Energy Conservation Office, SECO PV Fact Sheets, Estimating PV System Size and Cost International Energy Agency, Published papers by I. A. Altas,

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