SOLAR ENERGY: THE.SNAGS

"The only reason why solar energy has not yet been developed is that the oil companies don't own the sun." You guessed right; that idiotic statement was made by Ralph Nader.

But the real troubles with solar energy lie beyond Nader's fertile imagination. Of course, if by solar energy one means small scale conversion to heat, enough to provide some warm water and help to heat a house, then solar energy is here already. Such systems are essentially based on the same idea as leaving a long garden hose in the sun for several hours to heat the water in the hose. The sun's heat is absorbed by water tanks or other elements mounted in the roof or the south wall of a houses and when the sun is down, the absorbed heat is prevented from escaping by shutters or other devices, so that the heat is convected or radiated into the interior of the house. Some systems also include storage of heat in rocks or other bodies with large heat capacities, and more sophisticated systems can also reverse the process for cooling a house in the summer.

Such heat pumps of one kind or another have been in use for some time in two sunny and technologyminded countries: Australia and Israel. Several houses heated and cooled by solar energy have also been built in the US, and some systems are now commercially available. An Australian warm water system called Solapak may shortly be imported and distributed by Solar Energy Digest, Box 17776, San Diego, CA 92117; dome type homes heated by solar energy are custom designed by Zomeworks, Box 712, Albuquerque, NM 87103; and a book of Solar House Plans with actually tried models can be obtained for $10 from Edmund Scientific Co., 555 Edscorp Bldg., Barrington, NJ 08007.

But these systems do not come cheap. They also use much space of a home, and most of them are cumbersome the Zomeworks model, for example, uses shutters weighing some 100 Ibs each, moved by pulleys and winches. Solapaks (which only provide a warm water supply) entail adaptations of existing homes, and homes heated by the sun must be designed as new homes Mom the outset. Also, the systems do not provide all of the required heat, though they certainly reduce fuel bills drastically. But even in Arizona or Florida. they cannot be expected to provide more than some 80% of the needed heat.

So by cost/effectiveness standards, the most attractive and immediate solar heat pump is probably formed by large windows facing south, with the curtains drawn when the sun goes down hardly the thing to vanquish the energy crisis completely.

Solar energy (light rather than heat) can also be converted to electricity directly by semiconductor cells; this is how spacecraft are powered. There are several obstacles to this method for domestic use, of which by far the biggest, at present, is cost: a staggering $50,000 per kilowatt of output power. Although the cost is down from $100,000 per kW only a year ago, the price is as yet nowhere near feasibility for mass production. Solar One, a widely publicized model house built at the University of Delaware this year, uses this method for powering a home, including heating, cooling and energy storage. But the research project cost some $600,000, of which the cost of the actual house was estimated at $130,000 hardly a home for you and me yet.

But even if the price of solar cells were to drop to a few dollars per kW tomorrow, the system would still entail problems of space, complexity and skilled maintenance. However impressive such systems may be in individual cases, the efficient way to harness solar energy for mass consumption is, as in all other cases, to convert it centrally on a large scale and distribute it to the consumers.