Active Solar Energy
Explained

Active solar energy is the conversion of solar energy into usable heat via electrical or mechanical equipment - such as pumps and fans - which increase the usable heat in the system.

Solar energy collection systems that do not use external energy, like a solar chimney, are passive solar technologies.

Active solar systems use solar collectors and additional electricity to power pumps or fans to redistribute the sun's energy.

The heat is collected, then transferred to another location for immediate heating, or for storage for use later.

There are two types of active solar energy systems based on what is heated in the solar energy collectors. (The collector is the device heated by the sun.)

The first type are liquid-based systems which heat water or an antifreeze solution in a "hydronic" collector. The second type are air-based systems where air is heated in an "air collector."

Active solar power can be used to heat domestic hot water, warm up swimming pools and to heat water for commercial facilities such as laundries and fitness centers.

If you want to heat your home with solar energy, you need to decide whether you want an active or a passive system.

Passive systems are popular because of their simplicity, however they are sometimes impractical to install in an existing home. Active systems are often more practical for such applications.

Solar hot water systems - except those designed to work by thermosiphon - use pumps or fans to circulate water or an anti-freeze mixture, or air through solar collectors. Therefore they are a perfect example of an active solar technology.

Active solar power systems should be designed to provide between 40% to 80% of the home's heating needs. Any system that provides less than 40% of the heat for a home are very rarely cost-effective. A few exceptions exist, such as when using air panels for walls and collectors that heat one room and require no heat storage.

There are a number of factors to consider when choosing an active solar system. If you are planning to buy a system, you need to accurately determine how large your system should be. Computer software is often used to properly size active systems.

Solar panels and photovoltaic's are used to convert solar energy into electricity. As such, they are not classified as passive or active solar energy technologies.

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