Solar thermal collector for water heating. (Source: © Michal / stock.adobe.com)

A device that converts solar radiation into heat that can be used to heat water, air or generate electricity. Usually it is a black-painted glazed panel. The sun’s rays pass through the glass, transferring their energy to the panel and heating it. Because the glass does not let infrared radiation out, a high temperature is produced in the space between the glass and the panel, which can heat water or air. More complex solar collector designs use various methods to increase efficiency, for example by using evacuated tubes.