Solar hot air systems primary use is for providing heated air for home heating needs. This is done with a solar collector panel. Collector can be mounted on roof or wall that has clear unobstructed view of the sun. In northern climates a wall mount may be preferred. Any object that blocks sun light from reaching the solar collector will reduce the heat output .
How it works. The sun light passes through the glass onto the absorber plate. A temperature sensor in the collector panel sends a signal to differential controller. The differential controller compares the interior air temperature to panels temperature. When the sun has heated the panels interior temperature above homes air temperature the controller turns on a circulation fan. Cool air is blown threw the collector. As the air is blow through the collector it is heated by the collector plate. The heated air is then returned to the home. The fan continues to run until the home is sufficiently heated, or the collected has cooled to the level that heat can no longer be extract from the solar collector.
Solar hot air systems are not very complex. The only electronics need is the the differential controller, two temperature sensors, and air circulation fan. Some creative people have constructed their own solar collector panels. It's not recommend for most to construct their own. Yes you can save money by building your own panels. But ones that have been manufactured will last longer, and perform better. Because a company can afford to hire engineers to design, a efficient, reliable panel. A well established company can draw on it's years of experience in panel construction.
The solar collector panel construction consists of insulated flat box. On one side their is a flat plate glass window that allows the sun to shine in on to the black collector plate. The sun light warms the collector plate. Air is blown over the backside of the collector transferring heat to the air. At night when sun goes down, the collector will cool down. To prevent the cool air from entering the house, dampers in the air ducts close because the air circulation fan has been turn off. These damper open because air pressure from the fan forces them open.
On the plus side most solar hot air systems are simple and quite reliable. On the negative side the colder it gets out side the less heat you get from the collector. So lets say you have a day were temperature drops below 0 deg F or lower. You will not be getting much heat out of the solar collector. The reason for this is because the larger heat difference causes a greater amount of heat loss. And of coarse if you have cloudy weather heat output may be non existent. These systems produce their most heat during the summer when the days are hot, and long. Of coarse this is when you don't need heating.
In selecting a panel look for one that is well insulated. Well insulated panels will help reduce your heat lose during cold weather operation. This will help boost cold weather performance.
The Solarsheat 1500G is owned by the author of this web site. Author home is located in Wisconsin. The Solarsheat 1500G has it's own PV panel that powers the internal fan. The solar panel does produce significant heat on clear sunny day. Air exit 114 degree F. when the outside temperature was only 16 degree Fahrenheit. Inlet temperature was 72 degrees. The Solarsheat 1500G fan does make a significant amount of noise. The good news is that this is only during the daylight hours. The product does work quite well, and I would recommend it. Additional non PV powered panels can be added at a lower cost if increase heat output desired.
Manufactures of solar hot air panels.
Estimated Peak output 5000-6000 (Btu/hr)
AAA Solar Supply Inc. www.aaasolar.com
RA 240 SolarMax
Estimated Peak output 9500 (Btu/hr)
Cansolair Inc. www.cansolair.com
Low Profile UB Solar
Estimated Peak output 2048 (Btu/hr)
ClearDome Solar Thermal www.cleardomesolar.com
On wall, and In wall
DeSoto Solar www.iedu.com/DeSoto
Estimated Peak output 3000 winter, 4000 summer (Btu/hr)
Estimated Peak output 7800 to 15,600(Btu/hr) open loop type.
Conserval Engineering Inc. www.solarwall.com
Sunmate hot air solar panel
Sunmate solar panels www.sunmatesolarpanels.com