Energy Basics: Renewable Energy

Thousands of homeowners are using solar power to heat their homes and their water, as well as provide natural lighting.

Daylighting

"Daylighting" is one of the easiest and most cost-effective ways to use solar energy at home. This technique involves building a house to take advantage of the sun's rays.

The architect and builder work together to "site" the house on the lot to bring in natural sunlight throughout the day. Windows are strategically positioned to provide adequate light without overheating the area, and the interior design is planned to diffuse the light throughout the room.

According to the U.S. Department of Energy, a home built with "daylighting" techniques can have lighting costs 40 to 60 percent lower than a typical home.

Learn more about energy-efficient lighting

Solar water heating

Another "passive" method of using solar energy at home is a thermal solar water heater. These systems use the familiar flat glass or plastic panels seen on roofs and in backyards.

Sunlight passes through the panels and is collected by a dark absorber plate. The plate warms liquid passing through pipes - either the household water supply or an antifreeze solution that is used in a heat exchanger in the water storage tank.

Solar water heaters are popular in areas that do not have natural gas service - replacing an electric water heater with a solar model can reduce water heating costs by 50 to 80 percent every year. And over the 20-year lifespan of the equipment, more than 50 tons of carbon dioxide emissions will be displaced.

The initial cost of a solar water heating system ranges from $1,500 to $3,000; in many cases, the cost will be paid back in energy savings in less than eight years.

If you're interested in a solar water heating system, be sure to check your local building codes - many communities require a conventional water heater as a back up.

Did you know?
Enough sunlight falls
on the earth's surface
each minute to meet
world energy demand
for an entire year.

Photovoltaics

An emerging type of residential solar power is called photovoltaics. This technology uses semiconductor material to convert sunlight directly into electricity - if you have a solar calculator or watch, you're already using photovoltaics. More than 10,000 homes in the United States are entirely powered by solar energy.

The advantages of a photovoltaic (PV) system are numerous: it's non-polluting, there are no moving parts, it operates silently and requires little maintenance. Photovoltaic power can also be stored in deep-cycle batteries for evening or back-up use.

But economically, photovoltaics are rarely cost-effective for the average homeowner. A PV system produces low-wattage direct current electricity, compared to the 120-volt alternating current supplied by utility companies.

This means PV set-ups require different wiring, along with an expensive inverter to be able to run appliances. Sizing a PV system to provide enough power to run high-wattage appliances like refrigerators, air conditioners and stoves can quickly put it out of most homeowners' price range.

Photovoltaics can be used to produce large amounts of electricity. PV power plants, located primarily in California, use massive lenses and reflectors to concentrate the sun's energy on a fluid-filled pipe.

The heated fluid is used to drive a conventional electric generator. As with wind turbines, solar energy is used to supplement existing fossil fuel power plants.

Did you know?
Silicon from one ton
of sand, used in
photovoltaic cells,
could produce as
much electricity as
burning 500,000
tons of coal.

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Brochures & fact sheets:

PowerHouse: Green Power – Energy for the Future
By Alliant Energy [PDF format]

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Learn more:

Renewable Energy for Kids

U.S. Department of Energy’s Office of Energy Efficiency & Renewable Energy

U.S. Department of Energy’s National Renewable Energy Laboratory