Solar Water Heaters

Solar water heating uses collectors to heat water directly, so it is a different technology from solar panels that make electricity.

• Passive systems (batch or thermosiphon) have no pumps and are simple, but are best suited to mild climates.
• Active systems pump water or a glycol mix through collectors and suit colder regions when they include freeze protection.
• Flat-plate vs evacuated tube collectors. Evacuated tubes lose less heat in cold weather; flat plates are often simpler and cheaper.
• Pool heaters usually use unglazed collector mats on a roof or rack, with the pool pump moving water through them. They extend the swimming season rather than heating in winter.
• Stock trough heaters keep water from freezing for animals; check they are safe for the animals using them.

Most home systems keep a conventional backup heater for cloudy spells. Ask installers about local rebates and tax credits, which change over time, and about maintenance such as glycol replacement and leak checks.