Solar energy can be converted into heat energy in a number of ways. The most common way to convert solar energy into heat energy is through the use of solar thermal collectors. Solar thermal collectors absorb the sun’s energy and convert it into heat energy, which can then be used to heat water, air, or other substances. Another way to convert solar energy into heat energy is through the use of photovoltaic cells. Photovoltaic cells absorb photons from the sun and convert them into direct current electricity. This electricity can then be used to power a heating element, which in turn converts the electricity into heat energy.