Putting Solar Energy to Work

With the exeption of geothermal and nuclear energy, the sun accounts for all forms of energy on earth. Wind, waves, hydroelectric power, biofuels, and biomass all are example of indirect form of solar energy. Even most nonrenewable forms of energy, such as coal peroleum, and natural gas, are really indirect forms of solar energy because they are derived from organic matter made possible by the sun.

Direct forms of solar energy on the other hand, can be used as the energy is reveived. Using daylight to illuminate interior spaces (called daylighting) is a good example.

Passive and Active Solar Thermal Systems

There are two types of solar thermal system for capturing the sun's energy: passive and active. A passive solar system captures the sun's energy as it enters a building without relying on a motor-driven circulator or fan. Once inside the house, the heat can be stored in the mass of the buiding and distibuted by natural means, such as conduction, convection, or radiation, or by forced means, such as with a fan.

In active solar thermal system, collectors capture the sun's energy as heat as it enters the collector and transfer that heat to a fluid. THe heated fluid is moved through the collectors by a motor-driven circulator or fan and taken to whre it can be used immediately or stored for later use.

{source: Convert Your Home to Solar Energy by Joseph R. Provey,Everett M. Barber}