Electricity from solar energy cells, still too expensive for widespread use in America, could be bargain-basement power for many impoverished third world countries, according to a Worldwatch Institute study released last week.

The report, entitled "Energy for Development: Third World Options," said many developing nations would find, if they studied the idea, that solar cells and other renewable energy techniques would be cheaper than central power plants and transmission lines to backward rural areas.

Conventional power plants also have to cope with an oil-short future, the study said. "The industrial world is designed to run on oil . . . If the developing countries invest vast sums of scarce capital copying today's industrial powers, the petroleum era will have passed before their investments bear fruit."

The potential market for solar equipment in the Third World is vast, according to author Denis Hayes, a situation which is "so manifestly in the interest of the industrial world that it warrants granting Third World customers subsidies on early orders," as France is already doing.

The Worldwatch Institute is a Washington-based, nonprofit research group funded in part by the United Nations and private foundations to keep an eye on world-scale problems. The latest report, 15th in a series, said the Third World's energy crisis involves rapidly diminishing supplies of firewood, charcoal and forage for draft animals, as well as the coal and oil most poor nations have to import.

"Most of the fuel burned around the world provides heat at temperatures that solar collectors could easily achieve . . . using materials that are either indigenous to the third world or else recycled," the study said.

Trees being cut down for fuel are not only disappearing faster than they can re-grow, but their loss is causing erosion, lowering of water tables and the silting-up of dams used to provide hydropower, the report noted.

Solar power sources would include wind, caused by heat differences in the atmosphere, and bio-fuels, which involve plants and excrement fermented to provide burnable methane gas. All the available devices have a mixed history of success and failure in underdeveloped countries, Hayes wrote, and in some cases have been viewed as a threat to established employment and social patterns.

For example; "The use of solar cookers requires the adoption of new methods of meal preparation and restricts cooking to daylight hours . . . in programs in Mexico and India, the cookers failed to win acceptance even when they were given away," Hayes said.

"Because of poor maintenance and shortages of parts, windmills have been abandoned in Mali and Uganda," he wrote.

Political and institutional barriers are formidable, the report continued. "Officials have not wanted to settle for 'second-rate' renewable energy sources while the industrial world flourished on oil and nuclear power."

Nuclear power may be a false hope, "a trap for the Third World, Hayes wrote. "In many developing countries the cost of a single small reactor exceeds the value of all annual exports . . . most [countries] would be forced to rely on the good will of the nuclear vendors when parts wear out . . . and new equipment is needed."

Countries that have some exportable oil "might be wise to sell much of their oil at high prices to countries that have acquired a nearly paralyzing dependence on it," and invest the funds in developing renewable energy technology, the study said.

"New energy sources do not constitute a simple technical fix to the world's most difficult social and economic problem; the uneven distribution of wealth," the study concluded.