Solar Cells Fabrication Technologies

Transcription

1 Solar Cells Fabrication Technologies Crystalline Si Cell Technologies Amorphous Si Cell Technologies Thin Film Cell Technologies For a comprehensive tutorial on solar cells in general, see 1

2 Global Energy Sources projection Source: World Energy Council

3 The Growth Rate Captures the Attention Source: AMAT 3

4 Solar Facts The earth receives more energy from the sun in just one hour than the world uses in a whole year. 1% of the land today used for crops and pasture could supply the world's total energy consumption. The Sun provides 1020 Watts/meter² peak power at sealevel Cell efficiency of 10% translates to ~100W/meter 2

5 Commonly Known Solar Cell Materials

6 Fraunhofer

7 Beside efficiency, there are other considerations for ultilization 7

8 Projected Module Cost

9 Energy Content EG silicon Solar Grade Si MG silicon ~ 200 kwh/kg ~ 50kWh/kg ~ 20kWh/kg Energy Payback time Monocrystalline Si cell Polycrystalline Si cell Amorphous Si cell ~ 4 years 1.6 to 2.7 years 0.9 to 1.6 years. Richard Corkish,Solar Progress, (1997) 9

10 Comparison of commercial PV Crystalline Silicon Amorphous Silicon CIGS CdTe Organic Conversion Efficiency 13-18% 5-10% 10-12% 10.5% 5% Current cost per Watt * $ $2-2.5 Material Shortage $0.6 (predict) $1.3 <$1 (predict) No Silane Indium Te(?) No Toxic Substance NA NA Cadmium Selenium Cadmium Tellurium NA Reliability Excellent Fair Good Good Poor Company in the field Suntech, SunPower AMAT, Dupont Nanosolar, Solyndra First Solar Konarka 10

11 Si Crystalline Solar cells are just large area semiconductor diodes Crystalline solar cells are usually wafers, about 0.3 mm thick, sawn from Si ingot 15% efficiency cells deliver 15 to 60 W/m² or kwh/m²/day (annual day and night average) in North America

12 From Ingot to Module 12

13 From Ingot to Module (cont.) 13

14 From Sand to Silicon Process generates four tons of silicon tetrachloride liquid waste for each ton of polysilicon produced. 14

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17 Minimize Kerf Loss 17

18 Generic Crystalline Si Cell Processing Al-Ag paste * Al-Ag fuses through SiNx to form ohmic contact 18

19 Backside Al contact (BSF= back surface field p+ layer) 19

20 Belt Furnace Max T =950C 20

21 50 MW fab cell line. (Source: Applied Materials)

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25 Antireflection Coating Materials 25

26 Diagnosis of Crystalline-Silicon Solar- Cells Utilizing Electroluminescence: save production costs by sorting out defective solar-cells in an early stage 26

27 Module Packaging Source: Spire Corp 27

28 Crystalline Si on Glass (CSG) Solar Cell * All fabrication done with Laser processing and low-temperature PECVD

29 Sliver Cell A wafer (assume 150mm diameter) configured as a conventional solar cell has an area of 177cm2. However, the same wafer, when processed to produce Sliver cells, can be used to cover up to 5,000 cm2 of module area, which is 30 times better than for conventional technology. 29

30 Motivation for amorphous Si Cell Both silicon and thin-film PV solutions require a reduction in cost/watt. (Source: Applied Materials)

31 Rigid and Flexible a-si Solar Cells 30% T Ag n- a-si:h i- a-si:h Glass Textured TCO p- a- SiC:H ZnO Opaque (SS/Kapton) Glass / TCO / p / i / n / Ag SS / ZnO / p / i / n /Ag V oc Doped layers J sc i-layer defect density Cell efficiency, h = V oc J sc FF Light trapping P in FF i-layer defect density

32 Amorphous Si Deposition 32

33 Amorphous Si Deposition 33

34 a-si Cell Manufacturing Source: ULVAC Solar 34

35 Conceptual a-si Cell Fab Source: AMAT 35

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37 CIGS Solar Cells 37

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39 CIGS Manufacturing Source: pmc.org.tw 39

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43 Roll-to-Roll Manufacturing Source: Ascent Solar 43

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45 Needs MBE, MOCVD, or Layer Transfer 45

46 MW Technology Evolution 30%p.a. 25%p.a GW c-si thin film "New Concepts" RENEWABLE ENERGY FOR EUROPE - RESEARCH IN ACTION 46

47 Q: What are the major differences between PV fabrication and IC/MEMS fabrication? Patterning (alignment, size control) Doping Contact Formation Metallization Planarization Q: What other process modules are not commonly used in IC/MEMS fabrication?