Solar water heating systems

background

On average, 17% of a US home's energy and heating bill is spent heating water[1].

Conventional sources of heating, including heating water, are main contributors to a household's utility bill and green-house-gas (GHG) emissions[2].

Solar water-heating systems use freely available energy from the Sun to reduce the amount of utility-power consumed from heating water.

Solar powered water heaters offset GHG emissions and save water heating costs. The more that water is heated by the sun, the less energy from conventional sources is used to heat water.

system designs

Heating water by the sun can be as simple as painting a bucket black and leaving it in the sun.

Solar water heating systems work on the same basic principle and consist primarily of these designs:

• passive systems
• active systems
• closed-loop systems
• open-loop systems
• drainback systems - a hybrid that combines the best of open and closed loop designs

There are many variants that accomplish the same result. Some variations use parabolic troughs, concentrating mirrors, freon or oils as a heat transfer fluid, and vacuum tubes etc.

The majority of solar hot water heating systems installed in the United States are highlighted above. They are popular because they are cost effective and their performance has been proven over decades of use.

1 - according to the US Energy Information Administration (EIA) data (with normal range of 13% to 26%).
2 - extrapolated from EIA data with GHG and co2e equivalents from The Climate Trust.