An unglazed perforated plate collector is a type of solar collector that uses an industrial-grade siding/cladding perforated with many small holes at a pitch of 2–4 centimeters. Air passes through the holes in the collector before it is drawn into the building to provide preheated fresh ventilation air. Efficiencies are typically high because the collector operates close to the outside air temperature. Perforated plate collectors can be very cost-effective, especially when they replace conventional cladding on the building, because only incremental costs need be compared to the energy savings.

 

The most common application of this collector is for building ventilation air heating. Other possible components for this system are: a 20–30 centimeters air gap between the building, a canopy at the top of the wall that acts as a distribution manifold, and by-pass dampers so that air will by-pass the system during warm weather.

 

Another application for the perforated plate collector collector is crop drying. Systems have been installed in South America and Asia for drying of tea, coffee beans, and tobacco.