Electrical, potential, kinetic, heat — our lives require mass amounts of energy.

In physics class we learned that energy never disappears, and that in changing forms it loses quality — a principle called entropy.

But one home-energy solution, solar-thermal, gives entropy a run for its money. Unlike solar-electric energy, which converts just 10% to 20% of the sun's heat to electricity, solar-thermal transfers 50% to 85% of the sun's heat into heated water, according to manufacturers.

“People are waking up to the fact that we're rapidly using up fossil fuels,” says Freeman Ford, founder of Fafco. “But these systems are highly efficient, and that, combined with tax credits and a quick return on investment, makes them attractive to homeowners and to builders.”

Rooftop panel layouts facilitate solar hot water heating and can be expanded to accommodate radiant floor heating requirements.
Rooftop panel layouts facilitate solar hot water heating and can be expanded to accommodate radiant floor heating requirements.

Generally, solar-thermal can handle up to 75% of a home's hot water needs, with traditional systems used for backup. However, not all systems operate identically. In Stiebel-Eltron's setup, copper tubing carries special fluid behind roof-mounted flat panels to gather heat. The fluid routes back to a heat-exchanger coil in the water tank to heat household water. Meanwhile, Fafco's Hot2O system (above) uses plastic solar collectors and pex tubing. Water channels through the panels to absorb maximum heat from the sun.

Rest assured, solar water heating isn't just a benefit for residents of sunny weather states. Stiebel-Eltron's technical support specialist Ernie Wilson sells systems nationwide and uses a computer program to help customers find the right system for their location and family size. Priced from $2,000 to $8,000 depending on the system, most homeowners can expect to get a return on their investment in three to seven years.