Although they represent an immature industry, several solar energy technologies now seem ready for takeoff. This fact puts recent pessimistic news reports of solar energy prospects in a brighter perspective. These have dealt mainly with the problems faced by the manufacturers of flatplate solar energy collectors. In fact, flatplate collectors -- the glazed metal hot boxes that can be mounted on wall or roof to heat water or air -- represent only one of several solar technologies. These other approaches do not necessarily share the flatplate makers' problems.
Thus, while some solar technologies may be encountering difficulties, the overall outlook appears to be one of solid, if not spectacular growth during the coming decade.
Other technologies include so-called "passive" solar energy building design (for example, making the most of south-facing windows), the photovoltaics or solar-cell industry, use of concentrating solar collectors to provide process heat for industry, and wind energy machines.
Referring to these, Richard Munson of the Solar Lobby, says, "The people I have talked to recently have been very upbeat."
This upbeat view also is reflected in a recent Battelle Laboratories study of employment in the solar field. It found that 22,500 people were working in the solar energy field in 1978 and predicted this number would double by 1981 and nearly triple by 1983.
It is true that the current economic recession and high interest rates have hurt flatplate collector manufacturers, especially members of the Solar Energy Industry Association (SEIA). By number of companies, they represent about three-quarters of the current industry.
"Clearly, flat-plate collector sales have not met expectations," says Dana Moran of the Solar Energy Research Institute (SERI). He believes that both the federal government and industry must take some of the blame for this.
Congress took 1 1/2 years to pass solar tax credits. This appears to have depressed the market during that period. Following passage of the tax credit, the market picked up strongly. Last winter the industry had its best quarter ever, with $95 million in sales. Then interest rates soared, a housing slump followed, and solar retailers were caught in the credit squeeze.
However, according to a recent survey by Arthur D. Little, only 48 percent of American consumers are yet aware of federal and state solar tax credits.
"The industry hasn't reached out. It is true that the Department of Energy [ DOE] has not mounted any promotional efforts. But the SEIA has been equally as delinquent," says Mr. Moran.
Nevertheless, there seems to be a growing number of developers who see solar technology as an effective marketing tool. One of these is Harry Watson, an ex-airline pilot who has been involved with large housing developments in southern California and Colorado.
"[As a result of solar collectors] I have a market edge. Last quarter San Diego County had a [disappointing] number of sales, but we sold out our 48 units entirely," says Mr. Watson.
His condominiums sell for $62,000 to $67,000 in San Diego and $56,000 in Colorado. If this, he assigns $10,000 to the solar space and water heating system. That means buyers can deduct $4,000 from their federal income tax. But Watson reports there are not many developers like him around the country.
Most collector manufacturers are extremely small, employing fewer than 400 people. They are barely surviving, let alone able to support major marketing efforts.
This has led to the feeling on the part of many federal officials that participation by big companies is vital to the growth of the solar industry. Also, they see an increasing involvement on the part of utilities such as Long Island Lighting Company as a positive development.
Among "small is beautiful" solar advocates, these views are controversial. In fact, a recent article in the magazine Mother Jones charges that the DOE is aiding big business, particularly the oil companies, in their efforts to gain control of the solar industry. Author and solar activist Ray Reece argues that this is part of an overall strategy by big business to "control the pace at which solar power becomes a viable force in the energy market."
"We want to ensure that as the industry grows it remains competitive," says Mr. Munson, one of those concerned with increasing oil company investment.
Meanwhile, and although there are no hard figures, use of passive solar technology appears to be booming. "There appears to be a real explosion," observes Henry Kelly of SERI.
This growth has occurred despite the lack of federal tax credits for passive solar design.
Yet for several years solar experts have realized that passive is the most cost-effective type of solar energy. "The rational way to approach [solar heating] is: first, conservation; second, passive; and third, active [flatplate collector] systems," says Mr. Kelly, adding, "Yet what we have in tax incentives is 15 percent conservation, 0 percent passive, and 40 percent active."
Pending legislation would give builders tax credits for including passive solar heating. The recently formed Passive Solar Industry Council has been lobbying hard for this measure.
Another solar technology that may be on the verge of major expansion is the use of trough-shaped solar collector-concentrators that track the sun and generate high-temperature steam -- a technology that can be used in a number of industries.
So far, the bulk of the activity in this field has been government demonstration projects. But "the time is absolutely right for attacking the commercial market," believes Robert Mawhineey of Acurex, of the most successful firms in this field.
"We have several other situations where we feel solar is cost-effective, but we don't want to give them away to our competitors," Rick Nelson of Acurex acknowledges.
Wind energy appears to be in a similar situation. So far, it has managed to capture an extremely small market, but the stage is being set for significant expansion.
"Wind has grown under the double-edged sword of limited federal involvement," says Ben Wolff of the American Wind Association. "As a result, the technology has grown rationally, but not nearly as rapidly as one might hope."
Through the 1970s, the sales of small wind-powered devices remained relatively constant at a few hundred units per year. Within the last year or so , however, sales have soared tenfold, he reports. While the cost of electricity has increased, the cost of wind turbines has remained constant. For a good wind site, these turbines can compete well with utility power at 7 cents per kilowatt-hour.
"We're starting to see the big companies -- the Grummans, Alcoas, the General Electrics -- enter the market," says Mr. Wolff.
The biggest problem with wind turbines signs are three years old or less, while designers are trying to perfect machines that will run reliably for 15 to 20 years. Currently, buyers of wind systems are people who enjoy tinkering. "It will be a few years yet before we have turbines which the average person can install and forget about," says Wolff.
Another bright spot on the solar horizon is photovoltaics. "We have reached the point where private investment has surpassed government spending. The boom is going full-tilt," says one of the pioneers in the field, Joseph Lindmayer of Solarex.
After five years of constant and relatively moderate growth, sales have skyrocketed this year, Mr. Lindmayer reports.
While the cost of conventional energy has been straining upward, the cost of solar cells has been falling. Today, it is possible to buy photovoltaic arrays for $10 to $12 per peak watt. Next year the price may drop below $10.
Although still considerably more expensive than central-station power, a large market has opened up in areas such as irrigation pumping, microwave towers , and for electricity production in third world nations.