Solar House Facts

An active solar house uses the sun for heating energy more often than it uses traditional sources, namely fossil fuels. To what degree, however, depends on the efficiency of the collectors, the type of solar heating system and your regional climate. Solar collection systems in active solar homes use either liquid or air, which becomes heated as solar energy is collected and stored and is then distributed throughout the home to transfer the heat. Liquid-based systems capture solar energy in a hydronic collector using either water or an anti-freeze solution; air-based systems involve air collectors that collect, store and distribute hot air (see References 1).

A passive solar heating home design does not depend on mechanical devices as active heating systems do. Although simply having wall-to-ceiling windows that face south might qualify at least part of your home as passive solar, there is much more involved in a successful passive solar design. According to the U.S. Department of Energy, there are five elements that make a passive solar design complete, each of which must work together: aperture, absorber, thermal mass, distribution and control (see References 2). In short, the apertures, or collectors, should face within 30 degrees of true south and receive full sunlight between the hours of 9 a.m. and 3 p.m. each day so that the storage element can retain sufficient heat for distribution via convection, conduction, radiation or supplemental blowers. Finally, the use of certain controls, such as awnings and thermostat-controlled fans, will prevent overheating (see References 2).

Small solar electric systems, also known as photovoltaic (PV) systems, generate electric power using solar cells consisting of semiconductor material. The sunlight jolts electrons free from their atoms, which then flow through a circuit that converts it into a usable electrical current. PV systems are usually mounted to a domicile's roof or a sun-tracking device and vary in size, depending on the available space and the resident's energy requirements. PV systems are reliable, pollution-free, and can offset the long-term cost of an office or household's utilities. (see References 3) There are many technical factors to consider when installing a PV system, so its best to hire a professional solar contractor to design and install the system for you.

The cost of modifying an existing home to become passive solar varies considerably depending on the home's structure and design, so this option should be explored thoroughly with a professional contractor. Installing an active solar system, however, will average between $30 and $80 per square foot of collector space and should last for decades after the typical 10-year warranty has expired (see References 1). The most cost-effective system will furnish 40 percent to 80 percent of the heat needed in your home and can significantly trim your energy bills, especially if the system also supplies hot water (see References 1). The cost of small solar electric systems varies depending on the size and design of the system, the amount of components, and whether the system is grid-connected or stands alone. The capital and operating costs associated with a small solar electric system can, often be offset by solar rebate programs or tax incentives offered in many states (see References 4).