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I. INTRODUCTION
No form of "alternative" or renewable energy has received more attention than photovoltaics. Literally billions of dollars have been spent researching materials and processes that directly convert sunlight to electricity. The first "solar cell" was made in the Bell Laboratories in the early days of the semiconductor revolution--about the same time as the first transistor. Clearly, the transistor already has revolutionized modern life. Yet people still talk about the future "photovoltaic revolution." Early commercial applications of photovoltaics still are operating some 25 years after installation, and hundreds of thousands of installations have been made. However, the sun's major promise as an energy source is yet to be felt. Nevertheless, public policy interest, government funding, and, most importantly, private risk capital continue pouring into this promising technology. The rationale for public support has its roots in the oil crisis of the early 1970s. Since that time, the motivation for public support, which began as a fear of imminent shortage of fossil fuels, has been broadened to include affordable rural electrification in the third world, environmental protection, and industrial policy for high technology exports.
This money and effort have created a relatively small but worldwide business poised on the brink of a commercial breakthrough. This paper explores the current state of the market and technology for photovoltaics and draws inferences for those who are attempting to push the industry over the brink into greatness.
II. PHOTOVOLTAIC OVERVIEW
Energy reaching the Earth's surface from the sun is measured in units of kilowatt hours per day per square meter (kwh/d/m sup 2 . The average amount of sunlight at any location depends on latitude, cloud cover, and atmospheric conditions such as humidity. The distribution of this energy is more uniform than commonly believed. The Olympic rain forest in Washington receives about 3 kwh/d/m sup 2 while southern Arizona, New Mexico, and parts of Utah receive about 7 kwh/ d/m sup 2 . A more common way to express this measurement is to give the equivalent hours per day of "full sunlight." "Full sunlight" is defined as 1,000 watts per square meter of global radiation. Therefore, Arizona at 7 kwh/square meter gets seven hours of full sun while the Olympic rain forest at 3 kwh/square meter gets three...