Solar thermal energy is a way to use the energy from the sun to heat things up. It works by using mirrors, lenses, and panels to reflect and concentrate the heat from the sun's rays. This concentrated heat is then used to heat water, air, or other materials to create hot water, hot air, or steam. This hot water, hot air, or steam can then be used in different ways. For example, people can use it to heat their homes, or to generate electricity.