How Solar Water Heating Works
All solar water systems work by preheating incoming water before it reaches your existing gas or electric heater, which becomes a backup heater. This means your existing heater does less work, saving energy and lowering your monthly energy expense. The sun's energy is captured by a solar collector consisting of specially coated flat copper plates inside a sealed, insulated, glass-covered frame.

Mr. Sun's system of choice, the Sol-Reliant water heating system, is a closed loop active drainback* system circulating distilled water. Heat is transferred from the fluid in the collectors to your potable water via a coiled heat exchanger in the solar tank. When the pump is inactive, the circulating fluid drains back down into a storage reservoir above the solar tank to prevent cooling or freezing in the collector. While some systems use sensors and controls to operate the pump, the Sol-Reliant system pump is energized directly by a PV collector. The brighter the sun, the more energy sent to the pump and the faster the flow. In weaker sunlight the pump slows down automatically, and when there is no solar energy to be gained the pump automatically stops. Less parts and zero household electricity usage make PV control a very reliable, cost effective solution. The diagram below is a generic model of how a drainback system works:
*Systems that circulate your incoming potable water through the collectors are called open loop systems, while those using a distilled water and/or antifreeze solution are closed loop. Closed loop systems transfer heat from the circulating fluid to your potable water via a coiled heat exchanger in your solar tank. Active systems use a pump to circulate fluid through the collectors, while passive systems rely on water pressure and convection.

For more information on how solar water heating systems work, consider signing up for one of our class sessions, or contact us with your questions.

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6125 NE Portland Highway Portland OR 97218    503-222-2468 or 1-888-SOL-RELY