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SOLAR HOT WATER SYSTEMS
Summary by Solar Assist
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Solar Hot Water systems can be used for a variety of purposes. The most predominant system is the solar domestic water heater. Since every home and many businesses use hot water year 'round this is a consistent load that can be significantly offset by simply preheating the cold city water that feeds the electric or gas water heater with solar heated water. The intensity of the sun varies with the seasons and so does the temperature of the solar water produced.

Summertime months typically result in nearly 100% solar heated water for a well sized system. The winter months average around 25-50%. This results in an annual average of about 60-70% of your hot water load being provided by the sun.

Simple proven technologies result in durable, efficient systems that insure your full value invested will be returned to you through lower utility bills. There are many usable and efficient solar water heating designs but the two predominant systems are the “Drain-back” and the “Closed loop glycol”. They both utilize rooftop collectors, a pump and control, and a “Solar Storage Tank” dedicated to maximizing energy gains from the sun. The primary difference is how they protect themselves from freezing. One “drains-back” and uses normal water in the solar loop. The other stays full and uses a non-toxic antifreeze to prevent the collectors from freezing.

Solar Hot Water applications span a wide array of temperatures from lower temperature pool heating, thru mid temperature domestic hot water to high temperature commercial and process heat. There are a variety of collector technologies optimized for different application temperatures.  These range from bare plastic absorbers for swimming pools, to the most commonly seen boxed and glazed "flat plate"  collectors used for domestic water heating and some space heating.  Evacuated tube systems, more effective at higher temperatures are becoming more common for domestic water heating and space heating also due to reduced costs.