Solar Domestic Hot Water

Uses solar-generated heat for domestic or commercial hot water for cooking, dishwashing, baths, showers, laundry.  Most solar water heating systems for buildings have two main parts: a “solar collector” and a storage tank.  The storage tank holds the hot liquid. It can be just a modified water heater, but it is usually larger and very well-insulated. Systems that use fluids other than water usually heat the water by passing it through a coil of tubing in the tank, which is full of hot fluid. Solar water heating systems can be either active or passive, but the most common are active systems. Active systems rely on pumps to move the liquid between the collector and the storage tank, while passive systems rely on gravity and the tendency for water to naturally circulate as it is heated. (NREL, Solar Hot Water)

Radiant Heating

These are systems that convert solar “radiation” into “heat energy.” Most systems use working fluids that are heated by the sun in “solar collectors.” The heat in the fluid is then distributed to a reservoir to store the heat energy, or to other parts of the system to utilize the heat energy. Radiant floor system uses solar-generated heat for space heating air in a home or building.

Solar Cooling

A solar cooling system uses the “heat energy” to power a “refrigeration” cycle. The heat energy is used to compress a gas, which, when expanded in another part of the system, cools a set of “coils.” Air blown over the coils cools, and is then used to air-condition the building. This process requires an extremely hot working fluid, so it is not yet an efficient process except in the sunniest of climates.