What about Solar Thermal Systems?

Please tell me about solar air heaters. There are commercial ones that are built into walls, retrofits for residences and window models. – James G., Bandon, OR

Solar thermal systems have been primarily geared to heat water in the recent market evolution of this cost-effective set of technologies. Some expansion in the recent market has been to tie traditional solar thermal systems into radiant heating systems (warm piping within floors). Solargenix Energy has tied higher-temperature concentrated solar thermal into absorption coolers, used routinely with natural gas, for larger building installations. Conserval’s ( transpired solar collectors have been making inroads into the commercial/industrial markets, preheating air in the ‘air intakes’ of large buildings. Solar air heaters, which were plentiful in the 1980s, took a market downturn after the residential solar tax credits expired in the mid-1980s, and a few companies have begun to re-introduce them into the market. These units usually are attached to south-facing windows or into air intake ducts into the building. They work fine, and I used to recommend them for porch rooms and other rooms without heat, as a low-cost way to keep these areas livable in colder weather. Frankly, until this market grows and the handful of manufacturers works with Solar Rating and Certification Corporation (SRCC) to rate their collectors, the market will grow more slowly than for other kinds of solar thermal systems. There is no reason this segment of the solar industry should not grow and I have seen some interesting systems incorporating PV-powered fans to distribute the hot air from these units throughout the building. Only time will tell. — Scott Sklar