In Goleta, Calif., Dodd Geiger's 100 acres of avocado and citrus trees are drip irrigated with power from a bank of solar cells.
One night last June, when 80 m.p.h. winds from a tropical storm hit Tampa Bay , Fla., Mike Rankin's lights stayed on when most of the city was plunged into darkness. Mr. Rankin, a solar-cell distributor, powered his house with electricity generated by a photovoltaic array and stored in batteries.
One thousand villagers in Boera, a rural village in Papua New Guinea, now have running water pumped by 16 solar-cell panels. Nearby is a defunct windmill and parts of a gasoline engine: mechanical pumping systems that failed because no one in the village knew how to maintain or repair them.
These cases, culled from a recent newsletter of a solar-cell manufacturer, illustrate the central thesis of the latest report by the environmental think tank, Worldwatch Institute: that the space-age technology of solar photovoltaics is well on its way to becoming ''one of the most rapidly expanding energy sources - and one of the biggest growth industries - of the late 20th century.''
The solar cell, a cousin to the transistor and computer chip, does not fit the popular, counterculture image of the solar-energy industry, observes Christopher Flavin, author of the study, ''Electricity from Sunlight: The Future of Photovoltaics.''
''It is a world of high-technology laboratories, secret plans, patents, and weekly rumors of the 'latest breakthrough,' '' he writes.
Despite the tough economic conditions of late, the ''oil glut,'' the abandonment of a number of massive synthetic-fuel projects, the financial woes of the nuclear-power industry, and a substantial slowdown in the growth of conventional solar technologies, ''photovoltaics is a striking exception: a healthy 'sunrise' industry in a sea of economic and energy troubles,'' Mr. Flavin finds. In the last five years, world production of solar cells has increased by an average of 50 percent a year, he reports.
The reason for this is the revolutionary nature of the solar cell. Unlike virtually every other energy source, it has no moving parts. Sunlight striking a solar-cell wafer generates electricity. As a result, photovoltaic devices tend to be simple, rugged, reliable, and have relatively few adverse environmental side effects.
The big problem with solar cells is reducing their cost. Scientists at Bell Laboratories invented the solar cell in 1954 while looking for a practical way to power rural phone systems. But the device proved to be prohibitively expensive, several hundred times the cost of conventional electricity sources. Their invention was rescued from total obscurity by the space program, which needed a lightweight power source for satellites.
It was not until the 1974 Arab oil embargo that researchers seriously attempted to adapt solar cells for terrestrial power production. The result has been to reduce the cost by about 50 percent a year.
Even so, this remains an expensive form of power: Today it requires a $1,500 photovoltaic system just to power a 100-watt light bulb. Still, this is competitive in areas remote from power lines. And experts in the field predict that improvements in current manufacturing methods alone will slash costs by more than half during the next five years while also raising efficiency, Flavin reports.
As a result of continuing cost reductions, ''Worldwide annual production of photovoltaics is likely to rise to between 200 and 300 megawatts of capacity by 1990 and to over 1,000 megawatts by the end of the century. This will make the photovoltaics business a billion-dollar industry by the late '80s and push it close to the $10 billion mark by the year 2000,'' the researcher projects.
The United States government has been the leader in photovoltaics research and development from the beginning. However, the Reagan administration has slashed the federal photovoltaics budget from $150 million in 1980 to $50 million in 1983. At the same time, Japan and Europe have increased their support in the field severalfold, to the $150 million level.
''Ironically, a conservative, free-market government is ignoring the signals of the marketplace, boosting support for the fading nuclear industry while cutting off funds for rapidly growing solar-cell companies,'' Flavin comments.