Passive and Active Solar Technology Comparison

1. Passive solar heating. Typically, this consists of some sort of heat reservoir that has been painted black. Usually this heat reservoir is contained in an insulating space. This approach is often applied in sun rooms, agricultural buildings or green houses.

2. Active solar heating.  This is similar to passive solar heating except that the heat reservoir is manipulated in some sort of active way. The most common form of this technology is the heating of water for domestic hot water usage. Using a fan in a sun room or storing hot water for space heating all are examples of active solar heating.

3. Concentrated Active Solar Heating. This uses some sort of mirror or lens system to concentrate the sun's light on the collecting surface. The surface then stores the heat from the sun with some sort of active system. This system is probably the oldest form of capturing the suns energy on a large scale. The concentration allows for higher temperatures to be achieved which offers higher Carnot efficiencies for mechanical engines. The higher temperatures also allow solar energy to be used in applications that exceed 60 degrees C. This includes hot water space heating, or water purification systems.