Very often there is confusion about the various methods used to harness the sun's abundant and clean energy. Energy from the sun can be categorized in two ways: (1) in the form of heat (or thermal energy), and (2) in the form of light energy.

Solar thermal technologies use the sun's heat energy to heat substances (such as water or air) for applications such as space heating, pool heating and water heating for homes and businesses. There are a variety of products on the market that utilize thermal energy. Often the products used for this application are called solar thermal collectors and can be mounted on the roof of a building or in some other sunny location. The sun's heat can also be used to produce electricity on a large utility-scale by converting the sun's heat energy into mechanical energy.

Photovoltaics (PV) is a technology often confused with solar thermal and is in fact what many people mean when they refer to "solar energy". Photovoltaics (photo=light, voltaics=electricity) is a semiconductor-based technology (similar to the microchip) which converts light energy directly into an electric current that can either be used immediately or stored, such as in a battery, for later use. PV panels/modules are very versatile and can be mounted in a variety of sizes and applications; e.g. on the roof or awning of a building, on roadside emergency phones or as very large arrays consisting of multiple panels/modules. Currently they are being integrated into building materials (such as PV shingles, which replace conventional roofing shingles).