In a solar collector, the carrier fluid is heated by sunlight. Therefore, the heart of the collector are pipes that are exposed to sunlight. To increase the energy yield, the pipes are installed in a heat-insulated housing with a glass cover – taking advantage of the greenhouse effect. Sunlight passes through the glass cover with minimal loss and is converted into heat when absorbed by the tubes. At the same time, the glass cover is an effective barrier for this heat, so that the temperature inside the collector is higher than the outside temperature.