A solar forced air system simply draws the air from the home/business and into the collector, the sun heats the air, then a blower draws that heated air back into the structure. A controller turns on the fan when the collectors are hot from the sun and the thermostat asks for heat.

The collectors that GreenSky promotes and installs have some special adaptations: one are dividers that force the air to serpentine through the system for 2 benefits. It will "scrub the corners", utilizing the entire collector heating surface, plus, the air will stay longer in the collector obtaining a higher temperature.  

Also, this specialized solar air heater is equipped with a copper absorber plate located directly behind the solar glass and is sealed.  Your air actually circulates behind the copper absorber plate. The copper is anti-bacterial insuring you peace of mind.