All the non solar collector components needed to harness the solar energy that falls on the collector surface. For a solar air system this usually includes a fan, ducts, and a simple thermostat. For water based heating systems this usually includes a pump, piping, antifreeze, a storage tank, thermostat and heat exchangers to transfer the heat to domestic water or space heat. For a solar electric system it usually includes wiring, an inverter to convert direct current to alternating current, electrical switch gear to connect to the existing electric grid or building power panels or both, and sometimes batteries and battery charging and monitoring equipment to store electricity.