There are two forms — solar photovoltaic (PV) cells, which produce electricity directly from sunlight, and solar thermal. In a thermal system, two large, flat plates on the roof capture and store heat from the sun. That energy warms an 80-gallon water-storage tank. Heat is delivered in a variety of ways: radiant floor units, hot-water baseboards, hot-water radiators or with a central forced-air system.
- Solar panels take advantage of a renewable form of energy and reduce utility costs.
- A 30-percent federal tax credit is available for solar energy products.
- There are virtually no maintenance costs.
- Seeing a return on your investment can take longer: Solar thermal systems have a payback of five to six years, while PV systems generally have a payback at 15 to 18 years.
- The installation of a typical solar thermal system is about $7,500 to $9,000 and comes with a 10-year warranty.
- Make sure the panels are certified by the solar rating and certification corporation (SRCC www.solarrating.org).
Geothermal, literally meaning "heat from the earth," works by using a system of underground pipes that capture heat from the ground and transfer it back into the house.
- Very energy-efficient; most geothermal heating systems can also be reversed to provide central cooling as well.
- Homeowners who install a geothermal heat pump in 2009 or later are eligible for a federal tax credit of 30 percent of the installation cost.
- You'll usually see a return on your investment in four to five years for a 2,000-square-foot home.
- The life expectancy of a geothermal system is about 24 years; maintenance costs are minimal.
- Initial installation may be more expensive than other heating systems.
- Installing underground (vertical or compact horizontal) piping for an existing home may be more expensive; more economical horizontal ground loops are typically used for new construction with sufficient land.
- Getting the correct size unit installed in your home is important.
- The average unit size for a 2,000-square-foot house would be about three tons, and geothermal ranges from about $4,000 to $7,000 per ton.
Heat pumps use electricity to move heat from a cool space into a warm space, from the outdoors in during the heating season and from the indoors out during the cooling season.
- Heat pumps move heat rather than generate it; they can provide up to four times the energy they consume.
- High-efficiency heat pumps also dehumidify better than standard central air conditioners.
- Heat pumps meeting federal energy standards can qualify for a 30-percent tax credit, up to $1,500.
- Heat pumps are powered by electricity, so the cost to run them is tied to electricity rates.
- Heat pump compressors and fans can be noisy; look for a model with a lower outdoor noise rating and install the unit on a noise-absorbing base.
- When choosing a heat pump, look for the ENERGY STAR® label, awarded to those units with SEERs of 12 or greater and HSPFs of 7 or greater.
- Installation costs vary; a high-efficiency heat pump for a 2,000-square-foot house ranges from $6,000 to $12,000.