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TVA touting a cheap solar water heater it developed

To fan interest in solar energy, the Tennessee Valley Authority (TVA) has developed an inexpensive, do-it-yourself solar water heater. There is nothing fancy about it -- not even the name. The glorified crate, called simply the Sunbox, is expected to shrink a family's water-heating bill by 25 percent.

It is the TVA's first venture into the do-it-yourself arena, and the response to a series of workshops has surprised even Rudy Gibson, the program coordinator.

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"We reached about 2,400 people in seven states," he says, adding that consumer interest has compelled the TVA to expand the schedule and hold 48 seminars.

"We found hotbeds of solar interest which we didn't know existed," he adds. For example, more than 220 people flooded into a workshop held in Florence, Ala. In a Mississippi hamlet of 1,000 people, 6 percent of the population turned out.

"I think the valley is just waking up to solar," he adds. The thing about the Sunboxes is that just about anybody can build them.

"What we are trying to do is stimulate the interest in solar by designing low-cost units," Mr. Gibson reports. A good commercial solar water heater costs in the neighborhood of $2,500, but a Sunbox can be built for $450. However, he explains, the commercial units usually produce more energy.

A circular saw and a torch are the most exotic tools required. Unlike many solar water heaters, the Sunbox needs no pump, separate heat-transfer fluids, or controls. In fact, it has no moving parts at all. Rather, it is basically an insulated plywood box containing a water heater on its side.

The principle is basic: The sun heats the water in the black tank. If you have ever tried to drink water from a garden hose which had been coiled in the sun for an hour, you know the concept. The Sunbox is just a refined application.

Already some of the units have been built and TVA officials are in the process of selecting 70 of the homemade units for monitoring. About 600 people who attended the seminars applied for the $50 which TVA offered for the right to monitor the performance.

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Mr. Gibson says he was not sure how many of the units had been built, but the response to the monitoring program indicates there would soon be at least hundreds of Sunboxes in the valley.

The program has captured the attention of potential solar energy consumers far from the valley as well.

"We have been contacted by people from as far away as Rome," Mr. Gibson says. Unfortunately, the TVA will not make the Sunbox plans generally available until next spring when the monitoring program is scheduled to end.

The TVA do-it-yourself program will eventually include wood-stove installation, solar wall heaters, greenhouses, and movable insulation. The next phase is expected to begin in the summer of '82.

Mr. Gibson says he is confident the Sunbox program will stimulate the solar industry in the valley states of Tennessee, Kentucky, Mississippi, Virginia, North Carolina, Alabama, and Georgia. An unexpected spinoff might be commercially produced Sunbox kits, an idea initiated by a nonsolar company.

Ultimately, TVA will offer a do-it-yourself catalog listing a variety of workbooks that anyone can order.

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