Solar Water Heating Systems

background

On average, 13% to 26% (17% overall) of energy in a US household is consumed heating water[1].

Conventional household heating of water is a significant contributor to green-house-gases (GHG)[2] and a household's utility bill.

Solar water-heating systems significantly reduce the amount of utility power consumed in the process of heating water.

The reduction of utility power offsets GHG and heating costs. The more water heated by the sun, the less conventional, utility energy is spent heating water (and contributing to global warming). Read more about the costs and GHG associated with water heating sources.

system designs

Solar water heating systems 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 various modifications and variations of systems that utilize parabolic troughs, concentrating mirrors, freon, and vacuum tubes to accomplish the same result. More information on these other systems is available, but the majority of solar hot water heating systems installed in the United States are either passive, open-loop, or closed-loop systems as described, due to cost efficiency and proven performance over decades of use.

The drainback systems are becoming the most popular as these systems use the best of both closed-loop and open-loop designs, and manufacturers have continued to improve on it.

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