Proper Cleaning of a flat plate solar collector both assures the collector is capable of running at maximum capacity and maintains the life of the collector.
A flat plate solar collector is a box with a transparent cover usually installed on the roof or southern facing slope which collects solar heat. Light travels through the cover to the dark-colored coils inside causing heat energy transfer. If the transparent cover gets dirty or scratched the collector cannot run as efficiently.
In arid, windy, or smog laden areas more frequent cleaning is required. Frequent heavy rain can clean panels if hard enough to fully coat and wash the panel. Light rains often result in bonding the dust to the panels like glue, as does nightly condensation.
Step One - Apply Soap
Either by hand or with an extendable mop use a rag apply dish washing soap and warm water to the surface of the collector.
Step Two - Rinse
Rinse heavily with a hose to make sure that all firm and soap have been removed.
Step Three - Dry
Dry with a soft towel making sure to remove all moisture.
If accessibility is an issue pressure washing with 3.5 MPa (500 psi) can also be used.