Image: National Renewable Energy Laboratory,
via Wikimedia CommonsA window-mounted solar hot-air collector is often the best option for heating a single room. These devices come in pre-fab kits, and they can be built at home for just a few hundred dollars. These units are generally constructed from an insulated metal frame and a black metal plate for absorbing heat.
The metal plate has a special glazing in front to maximize the solar energy it can receive. The plate is heated by the sun and the air gathers in the collection unit. An electrically powered fan is used to pull heat from the solar collector into the room itself. For best results, this type of solar hot-air collector is often found on south-facing walls.
The roof mounted solar hot-air collector is the most common type found in whole home heating installations. Roof mounted installations are based upon the same principle as window mounted solar hot-air collectors but in a larger setting. Ductwork is also necessary to move the heated air from the solar hot-air collector throughout the entire home.
This type of solar hot-air collector uses several fans placed strategically throughout the home to draw specific amounts of heated air into different rooms. The idea of the solar hot-air collector is a fantastic one, but people who choose to install them should consider retaining an alternate source of heating in the event of inclement weather or very harsh climates.