Solar thermal collector
![Solar thermal collector dish](/Images/godic/202502/12/Russiasolar3804.jpg")
![Flat plate thermal system for water heating deployed on a flat roof.](/Images/godic/202502/12/Solar_panels,_Santorini23804.jpg")
![Evacuated tube collector](/Images/godic/202502/12/Vakuumroehrenkollektor_013804.jpg")
![An array of evacuated tubes collectors on a roof.](/Images/godic/202502/12/Solar_vacuum_tube_collectors_Thessaloniki3804.jpg")
A solar thermal collector collects heat by absorbing sunlight. A collector is a device for capturing solar radiation. Solar radiation is energy in the form of electromagnetic radiation from the infrared (long) to the ultraviolet (short) wavelengths. The quantity of solar energy striking the Earth's surface (solar constant) averages about 1,000 watts per square meter under clear skies, depending upon weather conditions, location and orientation.