Module 3. Solar Photovoltaic. Osamu Iso. Workshop on Renewable Energies November 14-25, 2005 Nadi, Republic of the Fiji Islands

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1 Module 3 Solar hotovoltaic Osamu Iso Workshop on Renewable Energies ovember 14-25, 2005 adi, Republic of the Fiji Islands 22-ov-05 (17:52) 3.Solar hotovoltaic Contents 1. Basic principles of V 1-1. Mechanism of generation Various type of V cell 1-3. Installation example 1-4. Basic characteristic 2. otential assessment 2-1. Basic principle of assessment 2-2. Insolation measurement 2-3. Estimation of annual generation power 2-4. Case practice 3. System configuration 3-1. Cells, Modules and Arrays 3-2. Type of system ( Grid interconnection or not ) 3-3. ower conditioner (Control system) 3-4. Batteries 3-5. Wiring 3-6. Some tips for system design 3-7. Case practice 2

2 22-ov-05 (17:52) 3.Solar hotovoltaic Contents 4. Example of equipment price 4-1. V module 4-2. Battery 4-3. ower conditioner 5. Design example of Solar Home System ( SHS in Indonesia ) 5-1. E7 Climate Change rojects 5-2. Renewable Energy Supply Systems 5-3. Reference 6. Design example of independent V system for small community 6-1. Basic condition and planning steps 6-2. Basic load estimation 6-3. System capacity design 6-4. Backup generator 6-5. Merits of small grids (compare with SHS ) 6-6. Case practice 3 22-ov-05 (17:52) 3.Solar hotovoltaic Contents 7. Design example of grid-connected V system and analysis of 7-1. String characteristics 7-2. Energy production 7-3. Observations and analysis 8. Design example of grid interconnected V system ( hilippine ) 8-1. Introduction 8-2. Outline of hotovoltaic system 8-3. Lessons Learned 8-4. hoto and Drawings 9. Maintenance 4

3 22-ov-05 (17:52) 3. Solar hotovoltaic 1. Basic principles of V 5 22-ov-05 (17:52) 1.Basic principle of V Contents 1. Basic principles of V 1-1. Mechanism of generation Various type of V cell 1-3. Installation example 1-4. Basic characteristic 1-5. Case study 6

4 22-ov-05 (17:52) rinciple and system configuration Characteristics of hotovoltaic Advantages (1) Clean Solar energy is a clean energy. It emits very small amount of carbon gases or sulfur oxides. (2) Infinite Solar energy is infinite and permanent. Disadvantages (1) Volatile in output The amount of sunlight varies according to seasons and weather. Therefore, generating electric power to meet the demand anytime is impossible. (2) Low in power density Regardless of the vast solar energy coming down to the earth, power density in sunlight can be as low as 1,000 watts/m 2. Acquisition of vast amount of energy needs vast surface area of the solar cell ov-05 (17:52) Capacity (kw) 2-2. Installed Capacity in the World Trends in hotovoltaic capacity in the world 2,000,000 Italy 1.4% 1,800,000 etherlands 2.5% 1,600,000 Australia 1,400, % 1,200,000 1,000, , , , ,000 0 USA 15.2% Other 8.2% Germany 22.7% Accumulated capacity[mw] at the end of 2003 JAA 47.5% 1,809,000kW Accumulated capacity Installed capacity per Accumulated year capacity Installed capacity per year Year 8

5 22-ov-05 (17:52) Mechanism of generation Mechanism of generation The solar cell is composed of a -type semiconductor and an -type semiconductor. Solar light hitting the cell produces two types of electrons, negatively and positively charged electrons in the semiconductors. egatively charged (-) electrons gather around the -type semiconductor while positively charged (+) electrons gather around the -type semiconductor. When you connect loads such as a light bulb, electric current flows between the two electrodes. Solar Energy hoto Voltaic cell + - Electrode Reflect-roof Film -Type Semiconductor -Type Semiconductor Load Electrode Electric Current 9 22-ov-05 (17:52) Mechanism of generation Direction of current inside V cell Inside current of V cell looks like Reverse direction. Why?? Current appears to be in the reverse direction? By Solar Energy, current is pumped up from -pole to -pole. In generation, current appears reverse. It is the same as for battery. Looks like reverse 10

6 22-ov-05 (17:52) Mechanism of generation Voltage and Current of V cell ( I-V Curve ) Current(I) (A) A Short Circuit High intensity insolation Low intensity insolation I x V = W Voltage(V) Voltage on on normal normal operation point point 0.5V 0.5V (in (in case case of of Silicon Silicon V) V) Current depend on on --Intensity of of insolation --Size Sizeof of cell cell about 0.5V (Silicon) ormal operation point (Maximum ower point) (V) V Open Circuit ov-05 (17:52) Mechanism of generation Typical I-V Curve (A) Depend on cell-size 5.55A 4.95A Standard insolation 1.0 kw/m 2 Depend on Solar insolation Current(I) Voltage(V) 0.49 V 0.62 V Depend on type of cell or cellmaterial ( Si = 0.5V ) (V) 12

7 22-ov-05 (17:52) Mechanism of generation Illegal use Do not charge V by another power source. If you charge V by another power source and try to make normal direction current, the V will heat up and cease to function. Force to make normal direction current Do not create a short circuit when sunshine is being received. + - If a short circuit is created during insolation, large current will heat up V cell and cell will cease to function ov-05 (17:52) Various type of V cell Types and Conversion Efficiency of Solar Cell (ote) Single crystal = Mono crystal Solar Cell Silicon Semiconductor Compound Semiconductor Organic Semiconductor Crystalline on-crystalline Single crystal oly crystalline Amorphous Gallium Arsenide (GaAs) Dye-sensitized Type Organic Thin Layer Type Conversion Efficiency of Module 10-17% 10-13% 7-10% 18-30% 7-8% 2-3% Electric Energy Output Conversion Efficiency = Energy of Insolation on cell x 100% 14

8 22-ov-05 (17:52) Various type of V cell Crystal cell (Single crystal and oly crystalline Silicon) 10cm 10cm Single crystal oly crystalline ov-05 (17:52) Various type of V cell Surface of V cell Aluminum Electrode (Silver colored wire) To avoid shading, electrode is very fine. Anti reflection film (Blue colored film) Front Surface (-Type side) Back surface is - type. All surface is aluminum electrode with full reflection. 16

9 22-ov-05 (17:52) Various type of V cell V Module (Single crystal, oly crystalline Silicon) Single crystal oly crystalline 128W (26.5V, 4.8A) 120W (25.7V, 4.7A) 800mm (2.62ft) Formed by melting high purity silicon, then sliced very thinly and processed into solar panel. 1200mm (3.93ft) 800mm (3.93ft) 1200mm (3.93ft ) Metal silicon pure enough to manufacture solar cell is poured into a mold and crystallized ov-05 (17:52) Various type of V cell Single crystal silicon production process Same as IC s process ulled up very slowly to make perfect crystal erfect crystal crystalgrowing is is possible. Efficiency is is high. high. rocess speed speed is is low. low. rice rice is is high. high. 18

10 22-ov-05 (17:52) Various type of V cell oly crystalline silicon production process Fragmentation Cooling Melting Re-crystallizing Cool slowly to make larger crystal Cutting Slicing Slicing Crystallization is is not not perfect. Efficiency is is lower lowerthan single single crystal. rocess speed speed relatively higher. rice rice is is lowerthan single single crystal ov-05 (17:52) Various type of V cell Improvement of oly crystalline production process To grow big crystalline cell Crack of crystalline causes law efficiency Molten silicon Avoid pollution Melting pot Cooling block Heater control Cool slowly, carefully Ideal control of ingot cooling process Improve ment 20

11 22-ov-05 (17:52) Various type of V cell Amorphous (on-crystalline) Silicon Solar anels Manufactured by applying thin-layer manufacturing technology for semiconductor Good for mass production. rice is lower than crystal type Efficiency is lower than crystal type Very flexible. Easy to fit on any shape of substrate. Glass substrate type Film substrate type ov-05 (17:52) Various type of V cell A-Silicon production process Like Rotary printer for news paper (good for mass production) unching Serial-hole forming SiH4 + O2 Metal electrode forming Si + 2H2O unching Correcting electrode forming LASER patterner Electrode patterning ( Vacuumed chamber ) Amorphous silicon forming Transparent electrode forming Back pattern electrode forming rotective film Lamination lasma forming process 22

12 22-ov-05 (17:52) Various type of V cell Comparison of type rice Efficiency 1 W size Current roduction Single crystal High % 1.0 about 30 % (Reference) oly crystalline Medium % 1.3 about 60 % Amorphous Low 7 10 % 1.7 about 10 % V cell size for 1 W power generation ov-05 (17:52) Various type of V cell Shear of type 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Japan USA EU Others Total Single Crystal oly Crystalline Amorphous Others 24

13 22-ov-05 (17:52) Various type of V cell Sun shine spectrum and V Sun Spectrum Amorphous Silicon Crystalline Silicon Relative Spectral response Ultra Violet Wavelength (nm) Visible light Infra Red Irradiance ( W/m) ov-05 (17:52) Various type of V cell roduction share of the world market KyoCera 8.8% EU 26.3% Others 11.7% 1,194.7MW (2004) USA 11.6% Japan 50.3% SHAR 27.1% SAYO 5.4% 26

14 22-ov-05 (17:52) Various type of V cell How to make V s silicon Raw Silicon Refining % Semiconductor Wafer for IC IC Chip Under developing (Expensive now) Garbage,Edge,Inferior IC Refining % (Melt again) Refining purity is lower than IC V To To get get cheaper silicon, recycled silicon is is used for for V. V. Amount of of raw raw material is is affected by by IC IC industry s production ov-05 (17:52) Various type of V cell Use insolation efficiently and reduce materials Texturized surface ( like a pyramid ) Low resistance fine patterned front electrode Anti reflection coating Back side reflective electrode Reduce reflection Slice thin wafer olycrystalline ingot oly Si wafer Wire saw fine wire saw 28

15 22-ov-05 (17:52) Various type of V cell Hierarchy of V Volt Ampere Watt Size Cell 0.5V 5-6A 2-3W about 10cm Module 20-30V 5-6A W about 1m Array V 50A-200A 10-50kW about 30m Array kw Cell 2 3 W Module,anel W 6x9=54 (cells) (modules) ov-05 (17:52) Various type of V cell Roughly size of V ower Station. In this conference room, how much V panel we can install? 1 kw kwv need m 2 lease remember 20m(65feet) Conference Room (We are now) 10m(32feet) Our room has about 200 m 2 We can install about 20 kw V in this room 30

16 22-ov-05 (17:52) 1-3. Installation example Roof top style ( Residence ) Main grid connected AC supply o battery ov-05 (17:52) 1-3. Installation example Roof top style ( School, Community-center building) Main grid connected AC supply With battery for emergency 32

17 22-ov-05 (17:52) 1-3. Installation example Roof top style ( Off grid power supply ) o Grid connection AC supply With battery Relay station on top of mountain Advertising sign beside highway ov-05 (17:52) 1-3. Installation example Roof top style ( Mountain lodge) Inverter and controller 1.2kW system o Grid connection AC supply With battery 34

18 22-ov-05 (17:52) 1-3. Installation example Stationary style Independent small Grid connection AC supply With battery Site: Mongolia Installation: May & June in 1999 urpose: For lighting, refrigerator and outlet in a hospital Solar cell capacity: 3.4kW Wind ower capacity: 1.8kW Inverter capacity: 5kVA ov-05 (17:52) Example Electrification of a village (in Thailand) Small Grid connection (3 villages grid) AC supply With battery The system supplies alternating current electricity to 240 residences in 3 villages. *Solar cell capacity: 151kW (total of 3 villages) *Type of solar cell: single-crystal *Inverter capacity: 100kW *Battery:7,700kWh (total of 3 villages) *Year of installation:

19 22-ov-05 (17:52) 1-3. Installation example Solar Home System (SHS) Solar array o Grid connection DC supply With battery Solar array Solar array Solar array Controller Light Storage battery ov-05 (17:52) 1-4. Basic Characteristic I / V curve and -Max control I pmax Current(I) (A) 1 A I/V curve I x V = W Voltage(V) V MAX V pmax To obtain maximum power, current control (or voltage control) is very important. ower conditioner (mentioned later) will adjusts to be most suitable voltage and current automatically Max control ower curve (V) 38

20 22-ov-05 (17:52) 1-4. Basic Characteristic Estimate current and voltage by I / V curve (A) A R = 0.05( Ω) If the load has 0.05 ohm resistance, Circuit current is 10 A Voltage is 0.5 V Then power is 10x0.5=5 W Current(I) R = V character V I Resistance character Voltage(V) R = 0.05( Ω) (V) ov-05 (17:52) Current(I) 1-4. Basic Characteristic I / V curve vs. Insolation intensity Current is affected largely by change of insolation intensity. artially shaded serial cell will produce current mismatch. (A) High intensity insolation Low intensity insolation I x V = W Bypass Diode 5A 1A (V) 5A 1A 5A 1A Mismatch 4A Bypass Diode 40

21 22-ov-05 (17:52) 1-4. Basic Characteristic Temperature and efficiency When module temperature rises up, efficiency decreases. The module must be cooled by natural ventilation, etc. Efficiency (%) % down Typical (25C) Amorphous cell Crystalline cell (%/deg) 0.25 (%/deg) Summer time on roof top (65C) Module Temperature (deg.c) ov-05 (17:52) 1-5. Case study Maximum power control Q : Calculate loaded power to resistance. ( I / V curve is next page) (Work) R = 0.02( Ω) R = 0.05( Ω) R = 0.10( Ω) 42

22 22-ov-05 (17:52) 1-5. Case study Maximum power control 12 (A) R = V I R = 0.05( Ω) 10 Current(I) Voltage(V) (V) ov-05 (17:52) 1-5. Case study Maximum power control 12 (A) R = 0.02( Ω) = = 2.58( W) R = V I R = 0.05( Ω) 10 = = 5.00( W) Current(I) R = 0.10( Ω) = = 3.31( W) (V) Voltage(V) 44

23 22-ov-05 (17:52) 1-5. Case study Maximum power control Q : Calculate loaded power to the resistance. ( I / V curve is next page) R = 0.02( Ω) = = 2.58( W ) R = 0.05( Ω) R = 0.10( Ω) Maximum = = 5.00( W ) = = 3.31( W ) ov-05 (17:52) 1-5. Case study Bypass Diode Q : Calculate maximum power of each system. a : o bypass diode. b : With bypass diode. ( I / V curve is next page) (Work) System a System b 46

24 22-ov-05 (17:52) 1-5. Case study Bypass Diode (A) 12 High insolation intensity 1max (0.5V,10A) Current(I) max (0.5V,4A) Low insolation intensity Xmax (0.6V,3A) (V) Voltage(V) ov-05 (17:52) 1-5. Case study Bypass Diode (A) For system a 3.6 W 12 High insolation intensity 1max (0.5V,10A) Current(I) max (0.5V,4A) Low insolation intensity Xmax (0.6V,3A) a 1 = = 1.8( W ) a 2 = = 1.8( W ) (V) Voltage(V) 48

25 22-ov-05 (17:52) 1-5. Case study Bypass Diode (A) For system b 7.0 W 12 High insolation intensity 1max (0.5V,10A) Current(I) b 1 = = 5.0( W ) 2max (0.5V,4A) Low insolation intensity Xmax (0.6V,3A) b 2 = = 2.0( W ) (V) Voltage(V) ov-05 (17:52) 1-5. Case study Bypass Diode Q : Calculate maximum power of each system. a : o bypass diode. b : With bypass diode. ( I / V curve is next page) System a System b 3A 1.8 W 1.8 W Total = 3.6 W 10A 4A Total = 7.0 W 5.0 W 6A 2.0 W 50

26 22-ov-05 (17:52) 1-5. Case study Temperature vs. Efficiency Q: Suppose there is a 50 kw Crystalline V system. (Work) If surface temperature rises to 65ºC, what is the system capacity? Efficiency (%) % down Amorphous cell Typical (25C) Crystalline cell (%/deg) 0.25 (%/deg) Summer time on roof top (65C) Module Temperature (deg.c) ov-05 (17:52) 1-5. Case study Temperature vs. Efficiency Q: Suppose there is a 50 kw Crystalline V system. If surface temperature rises to 65ºC, what is the system capacity? Efficiency (%) % down Amorphous cell Typical (25C) Crystalline cell (%/deg) 0.25 (%/deg) Summer time on roof top (65C) Module Temperature (deg.c) = 42.3( kw ) 13 Approx. 15% down 52