[PPT] - OUTLINE Motivation Silicon PV Technology Growth and Trends PowerPoint Presentation

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RECENT TRENDS IN PHOTOVOLTAICS TECHNOLOGY: CRYSTALLINE WAFERS VERSUS FLEXIBLE THIN FILMS

Saleem H. Zaidi, Gratings, Inc., Nov. 6, 2008

OUTLINE

Motivation Silicon PV Technology Growth and Trends Conventional Manufacturing (a) Automated Manufacturing (b) Thin Film Manufacturing Cottage Industry Approach (a) Application to 110 W Panel Manufacturing Silicon Solar Research Directions (a) Water-free Manufacturing (b) Crystalline Thin-Films

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ACKNOWLEDGEMENTS

Sam McCormack, Richard Marquardt, Matt Channon, Robert Ellis, Karen DeZetter, Laure Koltunski, David Modisette, Rich Winder, Rajiv Prinja, Abdul Latif, Gary Begay, Bernard Stuart, Dr. J. Tringe, and Prof. K. Sopian

Prof. S. Brueck, Dr. James Lyke, James Gee, Dr. D.

Ruby, John Wohlgemuth, and Steve Rockholm NSF, DoD, Sandia National Labs, UKM, and AFRL BP Solar, Adventsolar, LMCO

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INTRODUCTION TO GRATINGS

Turn-key solar cell and module manufacturing systems Multi-vapor etching systems Pulsed laser annealing systems Solar cells and Modules Nanostructures

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INTRODUCTION TO GRATINGS

Si nanostructure Au nanospheres Laser-etched Thru Features 110 W Panel 6-inch diameter Solar Cell

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United States 3816 billion KWh Annually Pakistan 66 billion KWh Annually Tanzania 1 billion KWh Annually

GLOBAL ELECTRICITY GENERATION

USA Russia Africa Green Land China Australia

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ELECTRICITY GENERATION VS GDP

Higher energy usage leads to higher income Most of the world at much lower income Quality-of-life linked to energy usage

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ELECTRICITY GENERATION IN ASIA

India and China will generate most electricity Coal usage will lead to environment degradation Climate is globally linked

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PARADIGM SHIFT IN ELECTRICITY GENERATION

Access to electricity is fundamental human right and responsibility Energy generation must be at the point of use Transition from macro grids (hundreds of miles) to nano grids (~ mile) Power plants from ~ 100s MW capacity to ~ 1 MW capacity Renewable PV technology to by-pass carbon-based fuels

FUNDAMENTAL ASSUMPTIONS

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COTTAGE INDUSTRY APPROACH TO PHOTOVOLTAICS

A solar cell is just a large area diode Manufacturing model based on IC model is not needed Energy conversion costs ($/W) is the key parameter PV technology is adaptable to a society’s technological level Investment in PV technology infrastructure (education, economy) PV technology creates jobs FUNDAMENTAL ASSUMPTIONS

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PV RESIDENTIAL APPLICATIONS

BIPV ~ 2-5 kW

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PV INDUSTRIAL APPLICATIONS

Industrial ~ 0.1-1 M W Agriculture ~ 0.1-1 kW Power Plant ~ 1 M W

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PV Power in MW PV Power in MW

Cumulative PV Power From 1990-2005 PV Power From 2001-2005

PV INDUSTRY OVERVIEW

Sustained Growth over Last 15 Years Grid-integrated PV is dominant Off-grid is economically profitable today!

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PV GENERATION SECTORS IN USA

Grid-connected ~ 90 % of the Total Significant residential and commercial sectors Off-grid growth is ~ 10 % of total

2005 installations ~ 100 MW

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IMPACT OF SUBSIDIES ON PV GENERATION

Residential Programs in Japan

PV Growth is dependent on subsidies Costs in Grid-connected regions still too high Off-grid regions, PV is the most economical

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PV GENERATION BY TECHNOLOGY SECTORS

Multicrystalline Si is Dominant Monocrystalline Si share has increased Thin-film technologies have reduced

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3.25 GW Generation 4 GW Generation

PROJECTED PV GROWTH IN NEXT FEW YEARS

Germany and Japan will lead growth China will compete strongly ROW and US may lag behind

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PV INDUSTRY OUTLOOK --- Wall Street Analysis

Huge financial growth in 2003 to 2008 with competing

technologies Period of consolidation 2009 through 2012 Financial activity will rebound, partly from merger and acquisition Grid-Parity ~ 2015

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PRINCIPAL PV TECHNOLOGY SECTORS

Raw material to purified Si Mono/poly silicon wafers from feedstock Wafer processing into solar cells Solar cell packaging into modules Module arrays for system integration

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PV TECHNOLOGY SECTOR: SILICON PURIFICATION

Si is the 2nd most abundant element on earth; Si is ~ 25.7 % of Earth’s mass Si is capable of supplying all our Energy

Raw SiO2 produced by Mining Purified Silicon Feedstock

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SUMMARY 2005

Hemlock 7,700 Wacker Polysilicon 5,600 REC 5,550 Tokuyama 5,200 MEMC 3,800 Mitsubishi Materials 1,600 Mitsubishi Polysilicon 1,260 Sumitomo Titanium 700 Other 220 TOTAL 31,630

Very expensive to produce purified Si Dominated by few companies Production of feedstock in tonnes annually

MAJOR PRODUCERS OF PURIFIED SILICON

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PV TECHNOLOGY SECTOR: MONOCRYSTALLINE AND POLYCRYSTALLINE SILICON MANUFACTURING

Cast Growth Poly-Si CZ-Growth Mono-Si Critical Technology Wafer manufacturing: key to success Mono-Si superior to and more expensive than Poly-Si Gratings focus on mono-Si

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BRIEF INTRO TO SILICON SOLAR CELL

Converts sunlight into electricity Silicon Wafer is processed into solar cell Current Extraction uses Screen Printing and Electroplating Optical Absorption in thinner wafers using 3D Structures Cell Efficiencies ~ 10-20 % range

Solar Spectrum on Earth Basic Cell Configuration

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PRINCIPAL SOLAR CELL MANUFACTURING STEPS

Damage Removal

NOTES: Technology Trend: Thinner Wafers and Dry Processing Need for Low-Thermal Budget Processes Replacement of Screen-Printing by Electroplating High throughput using Automated Equipment

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS Following IC manufacturing model High throughput to meet profitability

Automated Acid Etch System

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Automated Diffusion System

Several approaches are used POCl3 produces best results

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Automated Edge Isolation System Automated Nitride System

Several process approaches Proprietary and commercial systems PECVD nitride is often the most expensive machine

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Screen Printing System Contact Firing System

Low-cost screen printing options available Contact firing system is unique to screen printing

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Automated Solar Cell Tester

High Throughput Robotics for Cell Transfer and Sorting

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SOLAR CELL MANUFACTURING CHALLENGES High wafer cost relative to conventional fuels Wafer supplies for smaller companies High wafer costs High startup costs in extensive automation Harmful Chemicals Extensive water usage Lack of Innovation due to cost considerations

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THIN-FILM CIGS MANUFACTURING PROCESS

Large area vacuum equipment High power lasers

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TYPICAL CIGS PRODUCTION LINE Startup costs ~ US $ 30 million Annual production ~ 10 MW/year

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RETURN ON INVESTMENT PROJECTIONS High profitability High initial investment

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LOW COST MANUFACTURING PROCESS Modular approach Step-wise process characterization Efficiency ~ 15-18 % range

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SURFACE TEXTURING FOR PERFORMANCE ENHANCEMENT

RIE Texture Wet-Chemical Texture Spectral Reflectance

Cell Description Eff. (%) Open Circuit Voltage (V) Short Circuit Current (A) Fill Factor

Planar 14.5 0.611 1.269 0.786 RIE 16.48 0.617 1.434 0.781 chemical 16.96 0.619 1.452 0.792

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LOW VOLUME, LOW COST MANUFACTURING APPROACH PRINCIPAL PROCESSES and EQUIPMENT

LabVIEW Interface Coin stack Wafer Arrangement Etching Gas from Sidewalls 6”-diameter wafer capability

Gratings Edge Isolation System

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LOW VOLUME, LOW COST MANUFACTURING APPROACH PRINCIPAL PROCESSES and EQUIPMENT

Manual Solar Cell Tester

LabVIEW Interface Cells and Modules Programmable Power Supply

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SCREEN-PRINTED, TEXTURED 6”-DIAMETER SOLAR CELLS

Cell Description Eff. (%) Open Circuit Voltage (V) Short Circuit Current (A) Fill Factor

Wet- chemical 15.686 0.605 6.407 0.725

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PRINCIPAL SOLAR MODULE MANUFACTURING STEPS

Technology Trend: High throughput using Automated Equipment Combine Cell and Module Manufacturing Operations Opportunities for low-cost, Manual Manufacturing NOTES:

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Automated Solar Cell Tester and Sorter

High Throughput Robotic for Cell Transfer and Sorting

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LARGE VOLUME, HIGH COST MANUFACTURING

APPROACH USING TURNKEY SYSTEMS

Automated Solar Cell Tabbing and Soldering

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LARGE VOLUME, HIGH COST MANUFACTURING APPROACH USING TURNKEY SYSTEMS

Automated Lamination Module Tester

High Throughput at High Cost Robotic for Cell Transfer and Sorting

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LOW COST MANUFACTURING APPROACH PRINCIPAL PROCESSES and EQUIPMENT

Manual Cell Tabbing Manual Cell Stringing

Low cost and effective Employment oriented Simple throughput extension

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Manual Operation Light tables for defect detection Yields comparable to automated equipment

LOW COST MANUFACTURING APPROACH PRINCIPAL PROCESSES and EQUIPMENT

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LOW COST MANUFACTURING APPROACH

MODULE LAMINATION AND FRAMING

Manual operation Manual loading of laminator Manual Framing

Manual Laminator

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LOW COST MANUFACTURING APPROACH SOLAR MODULE LIV CHARACTERIZATION

Manual operation Manual loading of modules

Module LIV Tester

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Reduced startup cost and employment oriented

LOW VOLUME, LOW COST MANUFACTURING APPROACH BASIC FACTORY LAYOUT

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Cross-over point ~ 2 MW/year in US Cross-over point ~ 0.5 MW/year in developing country

COST AND BENEFIT ANALYSIS

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SILICON SOLAR RESEARCH DIRECTIONS

NEEDS FOR WATER-FREE MANUFACTURING

1 MW production requires ~ 10 million Gal DI water Harmful chemicals such as HF, HCl, NaOH Reduced yields for Thinner wafers Al BSF process incompatibility on Thinner wafers

PLASMA PROCESSES IN SOLAR CELL MANUFACTURING

Plasma texturing Plasma implantation Reduced thermal budget No wet-chemical processing

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PLASMA PROCESSES IN SOLAR CELL MANUFACTURING

IQE PLANAR

Wavelength (nm)

400 600 800 1000 1200

IQE and Reflectance

20 40 60 80 100

IQE--TEXTURED Ref--PLANAR Ref--PLANAR

Random RIE Texture Plasma implantation System Implant Profile Reflection and IQE

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SILICON SOLAR RESEARCH DIRECTIONS

NEED FOR CRYSTALLINE SILICON THIN-FILMS

Reduce energy conversion costs Flexible substrates Higher Efficiencies

THIN-FILM SOLAR CELL MANUFACTURING

Epitaxial growth Porous Si etching and de-lamination Reduced optical absorption Expensive and low throughput

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OPTICAL ABSORPTION IN THIN FILMS

Surface Texture Surface and Sidewall Texture Short-circuit Enhancement Short-circuit Enhancement

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OPTICAL ABSORPTION IN THIN FILMS

Short-circuit Enhancement Short-circuit Enhancement

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CONCLUDING THOUGHTS ON PV TECHNOLOGY

On-Grid PV Off-Grid Village-No Electricity PV Technology is Special Needed Most by Poorest of the Poor PV Technology is Expensive PV Technology Must Become Indigenous PV technology Must evolve Into Cottage/ Community Industry PV Technology Combines Silicon, Oxygen, And Sun---abundant and free

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SUMMARY: PV ENERGY IS THE ULTIMATE SOLUTION

A Shift in Energy Generation from Fossil Fuels to Renewables: a Paradigm Shift as Fundamental as That from Coal to Oil in 20th Century Paradigm Shifts We are Familiar With