A passive system has no moving parts other than motorized shades or insulation barriers to prevent heat loss at night through the glazing. The solar radiation becomes heat energy as it passes through the glazing and strikes the storage medium. A wall of concrete, a floor of concrete or stone, or large vertical cylinders filled with water are used to store the heat. At night, as the temperature of the home drops, doors between the storage room and the house are opened so the warmth that has been stored will radiate into the air and temper the home. Insulated shades or blankets covering the glazing during the night will keep external heat loss to a minimum.
Active systems are more complex.
The solar radiation that passes through the glazing falls on a collector plate. The plate can be a duct with air flowing through or a plate with loops of piping carrying water or refrigerant that is warmed and pumped to the space to be heated or to a storage facility. If air is used as the medium, a large bin of rocks or a layer of rocks beneath the floor of the house will absorb the heat to be stored. If water is the medium, it will be pumped to a tank, and can be circulated to a conventional radiator system when heat is needed. If a refrigerant is collecting the heat, it will follow the same design as a heat pump system.