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Southeast testing solar cells for home electricity

In a major move to make it practical for homeowners to convert sunlight into electricity, researchers at the Florida Solar Energy Center are setting up a $3. 8 million solar-cell test project involving a network of utility companies and public agencies throughout the Southeast.

The five-year program, funded by private as well as state and federal dollars , is designed to experiment with all aspects of photovoltaic (solar cell) systems.

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Researchers from the private and public sectors will work together to test state-of-the-art cells as well as various ways of affixing them to residential rooftops. Among other things they will also seek the safest, most reliable means of connecting the household solar systems to existing utility networks.

''This project allows us to do our homework ahead of time and make for a very orderly transition into residential photovoltaics,'' says Gerald Ventre, deputy director of the Florida Solar Energy Center.

''A congressionally mandated'' $2 million contract from the Department of Energy will cover setting up the project, which has been designated the Photovoltaic Southeast Residential Experiment Station, explains an Energy Department spokesman based in Washington.

Construction of test facilities at Cape Canaveral and laying all the groundwork is expected to take about two years, and will expend the federal funds. Then the regional participants (utility companies, state solar centers, and one university) are to defray expenses for the remaining three years of the project. Its aim is to provide the data and impetus for private industry to get photovoltaics out of the lab and onto the assembly line.

''This project is extremely important,'' Mr. Ventre says.

''Right now there isn't a residential market for photovoltaics because the cost of the cells is too high. We anticipate the cost of these cells will come down as mass production of them takes place. If the cells were at an attractive price right now we may have run into situations that should have been solved ahead of time.''

The Southeast solar-test network is the third and final such test program in the nation.

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Similar, scaled-down versions are already operational in the Northeast (Concord, Mass., managed by the Massachusetts Institute of Technology) and in the Southwest (Las Cruces, N.M., managed by the New Mexico Solar Energy Institute).

Researchers are to compare photovoltaic performance data from the three regions, in part to see if different solar cells must be used in different regions of the country.

The Southeast project, which began officially Oct. 1, may prove to be the keystone to widespread use of photovoltaics in American homes. The first two test facilities run tests at only one site. The program managed by the Florida center will test solar-electric homes at a half dozen or more sites in Florida, Georgia, Alabama, and Tennessee.

Part of the funding will be used to construct at least four photovoltaic prototype structures (simulated homes) for long-term tests at the Florida center , site of the nation's second photovoltaic house, which has been undergoing tests for two years.

A solar-cell test facility, also funded by Florida taxpayers, is nearing completion and will be used to interchange various brands of solar cells and components for short-term tests.

The Tennessee Valley Authority has four photovoltaic homes that will be plugged into the project. The Alabama Solar Energy Center and Georgia Power each have one solar-electric house committed to the project, says Mr. Ventre, who adds that ''every investor-owned utility in Florida has committed'' to the program.

In addition, he says that Southern Services Company, one of the nation's largest electric utilities, will be involved, as will Alabama Power. Further commitments are being sought.

One interesting aspect of this photovoltaic test network is that it coalesces public with private, state, and federal efforts. Sam Taylor, the Department of Energy's residential experiment station manager, explains the federal viewpoint of the three-region program:

''We are focusing on long-term, high-risk, high-payoff research. In general, the intent was to develop materials that would be cost-effective for the majority of the regions in the country, materials which industry can take and develop into products.''

Mr. Ventre explains that the majority of solar cells are made from specially treated silicon, which is crystalline and light-sensitive.

When light hits the cells there is electron motion, because part of the silicon has an electron shortage as a result of the special treatment. The electron motion results in direct-current electricity, which is changed into alternating current by a machine called an inverter.

It now costs about $50,000 to buy and install enough solar cells on a rooftop (about 5,000 watts) to supply the needs of an average four-person family. That translates to roughly 35 cents per kilowatt-hour, as opposed to the 7 cents or so per kwh. which the local utility companies charge.

Researchers hope to bring the cost of such a photovoltaic array down to $10, 000, which would put the solar kwh. cost on a par with that of local utilities.

High as the current price may sound, solar cells are already feasible in some cases.

''Photovoltaics are already being used around the world,'' explains the Energy Department's Mr. Taylor. ''They are cost-effective for certain remote applications,'' he adds. In areas not served by a utility, he goes on, it is frequently cheaper to use photovoltaics than to extend the utility service to the remote area.

Ultimately, solar experts envision linking home photovoltaic systems into existing utility systems.

During the day the homeowners' electric system would generate electricity for the house. Any excess would be fed to the utility, with the homeowner getting a credit for it from the utility. With such a credit system, a home solar system could conceivably produce enough electricity for the home to carry it through periods of no sunlight.

Nonetheless, many hurdles still remain. Surprisingly, those hurdles have less to do with the solar cells themselves than with the other necessary components, such as inverters, mounting hardware, and electric meters, which will have to measure output (for the credit) as well as consumption.

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