Solar Water Heaters

Tax credits help defray the cost of installing a solar water heater

As noted earlier, solar water heaters last at least 20 years, usually much longer, and add to the resale value of a house. They use free energy from the sun, and although they seem new and high-tech right now, they were actually used in many homes in the 1890s. The electrification of America sent them out of fashion until the energy crisis of the 1970s. Government support for solar energy lapsed in 1986, but there are now big tax credits available. The tax credit reduces the cost of a solar water heater by 30 percent for homeowners.

According to FineHomebuilding.com's Scott Gibson, people who use solar water heaters tend to conserve water. Based on this assumption, he estimates that each person needs only about 20 gallons of hot water a day. Unlike other types of water heaters, however, the sizing to produce this varies tremendously across the United States. For a family of four needing 80 gallons of hot water a day, a solar water heater would only need 40 square feet of collector area in Arizona, but 106 square feet in Vermont. (Our Useful Links section has links to articles that can help you calculate sizing for your area.)

All solar water-heating systems contain collection, storage and transfer components, but many design options exist. Reviews say it's important to study the options carefully to pick the best one for your climate and situation. Some designs are relatively simple to build yourself, and kits are also available. Other solar water heater systems require professional installation.

One simple solar hot water heater kit, the Solar Roofs Skyline, was designed in conjunction with the Department of Energy and gets an enthusiastic review at the DOE website. The modules mount directly on the roof, and they're lightweight enough to make this relatively easy. The Skyline 10-01 solar panel (*est. $300), which weighs just 19 pounds, is 6 feet long and provides 10 square feet of collection plate. The Skyline 20-01 (*est. $560) is twice as long and weighs 38 pounds.

You combine as many modules as you need to supply hot water for your climate. The warranty is for 10 years, and the mounting system is certified to withstand winds up to 150 mph. The Solar Roofs website shows how to configure different systems suited to your climate. For example, a closed-loop system circulates antifreeze through the system's tubes, protecting it from freezing. An open-loop system circulates water through the tubes, and is fine for climates that never fall below freezing.

As noted earlier, the cost-effectiveness of solar hot water heaters depends more on state and local incentives than on your living in a very sunny part of the country. The review at Fine Homebuilding notes that in Maine, a solar hot water heater for two people (with 32 square feet of collector area) could pay for itself in three or four years. Maine has long cold winters, but has better state incentives than sunny Florida, where Fine Homebuilding estimates a cost savings of only about $74 to $110 for two people using a solar hot water heater.

California and Hawaii provide excellent incentives for solar hot water heaters, and about 35 percent of household in Hawaii use them. This is partly because electricity and natural gas cost so much in Hawaii, but it's also based on environmental concerns. Hawaii is the first state to require solar hot water heaters for all new housing starting in 2010.

Unless your own concern for minimizing global warming and reducing air pollution makes you determined to install a solar water heater no matter what, reviews say your first step is to find out what state and local incentives apply in your area. FindSolar.com provides an online calculator that takes government incentives into account, along with your current utility rates, to estimate the payback period for a solar water heater. Our Useful Links section below provides links to many resources on solar hot water heater designs, specifications and ratings, plus links to manufacturers' website and articles on making or buying a solar water heater.

We did not find reviews of complete solar water-heating systems.