A Heliostat is a system of two flat mirrors that guides sunlight into a laboratory to serve as a source for irradiance experiments or measurements (see Figure 3). A tracking system follows the sun, enabling use for long periods of the day.
Although sunlight might not always be available, the Heliostat has the great advantage of delivering a solar beam into a laboratory with a well-defined beam geometry and spectrum. Laboratory experiments can then be conducted under controlled environmental conditions.
