Night time air cooling
The cooling function
On clear summer nights, a solar collector has its black surface exposed to the very cold night sky. As the solar radiation absorber is designed to very well exchange heat through radiation, it will be cooled by the night sky in a similar way it is warmed by the light of the day: through direct exchange of radiation. As a result, the air that passes through the solar collector will be also cooled, and when admitted in the house it will relieve the well-known summer night discomfort. However, this cooling effect is smaller than the heating effect that can be obtained during the day. We also have a model of solar air heater that cools a building during summer days and heats it during winter days.
We use this advantage of our solar collectors to extend their use through the warmer months. The diagram below shows the year-round usefulness of our solar air heaters in a temperate climate: