Extech’s SP505 measures solar power level from sunlight outdoors to determine the best location of solar panel and solar water heater installations. It is also used indoors by window manufacturers, the automotive industry, and remodeling home owners to check the level of solar radiation transmission through various glass thicknesses and degrees of tinting to use for window installations. The convenient, pocket-sized meter with a built-in precision solar light sensor is easy-to-use wherever you go.