No matter how high the cost of natural gas rises, Neil Luberhoff will still be paying about half his ''normal'' bill for hot water. Why? Because Mr. Luberhoff installed a preheater on his hot-water system at what might be termed a solar ''barn raising'' event.
Mr. Luberhoff, with a lot of help, built the low-cost ''breadbox'' heater at a six-hour, hands-on solar workshop led by Paul Erhartic, president of the Merrimac Valley Solar Energy Association.
Such self-help workshops are becoming more commonplace in the United States as people begin to realize that solar heating is cost-effective, according to Mr. Erhartic.
As revived from self-reliant pioneer days by alternative-energy enthusiasts, the ''barn raising'' event of today involves friends sharing food and helping to build alternative energy projects, such as solar porches, solar wall-collector air heaters, and solar water heaters.
Mr. Luberhoff's passive 30-gallon system cost $400 in materials, plus a two-hour plumber's fee to tie it into his existing system. After collecting federal and state tax credits, which amount to 61 percent of the cost, his net expense is $156 (plus 39 percent of the plumbing hookup fee). The pay-back period is two years.
By contrast, a 60-gallon passive off-the-shelf system would cost $1,200 and have a pay-back period of seven years.
The 30-gallon, black-painted tank is enclosed within an aluminum-frame plastic box that is insulated on all sides except the slanted, south-facing top. Municipal water pressure forces water through the sun-heated tank to the water heater inside the house.
The system, as it rests on the ground outside Luberhoff's three-story Victorian house in Newton Center, a few miles from downtown Boston, will preheat water nine months of the year, but will be drained in the winter months to prevent freezing.
Experienced, handy people, Erhartic says, should be able to build a solar water heater by themselves with what they learn at a workshop. Less-experienced workshop graduates, however, may need to invite one or two weekend plumbers or carpenters to their barn-raisings.
Scott Sklar of the Solar Lobby in Washington says the number of local solar activities is on the rise. For more information, look in the Yellow Pages of the telephone book under ''Solar,'' or get in touch with the state energy office.
The Luberhoff installation was sponsored by the Urban Solar Energy Association in Boston and the Merrimac Valley Solar Energy Association.