Thin-Film Amorphous-Silicon Photovoltaics

The search for a less expensive solar-generated electricity just might end up focusing upon the solar cell construction design of thin-film amorphous-silicon photovoltaics. Includes diagram and cost versus efficiency.

| November/December 1982


Diagram: Construction of a thin-film solar cell.


A low-cost electricity using thin-film amorphous-silicon photovoltaics is in the works. 

Imagine what would be possible if solar cells were available for 70 cents per watt! At that price, a fully equipped home would receive its electricity at a cost that's equivalent to utility-produced energy billed at 10 cents per kilowatt-hour (KWH). Power company rates now average 7 cents per KWH in the U.S., and the dime-per figure promises to be upon us all too soon. (In other parts of the world—Japan, for example—even that price is already a fond but fading memory.)

But is it really possible that solar cells will sell for 70 cents per watt in the next few years? The answer is yes, if current trends in thinfilm cell research are any indication of what can be done.

And one of the hotbeds of such investigation is Japan, which began to organize a national effort to study photoelectricity back in 1974. You see, that country recognized—nearly ten years ago—that fuel prices were going nowhere but up! Since then, photovoltaics researchers have taken great strides toward the goal of making solar electricity a practical, economical alternative to that generated with imported oil.

The Japanese investigated numerous alternatives, and—in 1979—settled on thin-film, amorphous-silicon technology as the best bet. In fact, many of that country's scientists anticipate that once the technology has matured, the cost of such cells could drop to 70 cents per watt by 1985 . . . and to as low as 25 cents per watt by 1990.


Unlike the popular single-crystal wafer I described a couple of issues back (see MOTHER EARTH NEWS issue 76, page 178), amorphous silicon has physical properties that can best be compared with those of glass. Instead of a rigid crystalline framework, the material has a more fluidlike form that lacks orderly structure. (In fact, the word amorphous means "without definite form".)

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