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Solar Thermal

When we discuss a solar system for a client’s home we are talking about one of two types of system. The first is a solar P.V (or photovoltaic) which generates electricity to help offset the power consumed in a household. The type we are discussing here is the second type which is called “solar thermal”, or sometimes just called solar hot water.

Solar Hot Water Heating

Solar Hot Water Heater DiagramThis type of systems consists of some type of panel or exposed piping with water or other liquid flowing thru it that is exposed to the sunlight on your rooftop. The simplest type is just a coil of black plastic tubing laying across the roof. This tubing is full of water and the sun heats the water in the tubing which then flows to the water heater. This acts as a pre-heater so the water heater doesn’t have to run so long to heat up the water to the desired temperature. The sun has already pre-heated it. Another type has tubing that runs thru a panel but instead of water in the tubing it’s some other liquid that is heated by the sun. This liquid is then run thru a heat exchanger where the heat it has absorbed is transferred to water that is then allowed to flow into the water heater.

Offset Your Heating Costs with Solar Thermal

One of the benefits of this indirect system is the liquid heated can have anti-freeze base which means you don’t have to be so diligent about draining the water out of the tubing during possibly freezing weather. There is a style being tried now where instead of having a water heater down in the house or garage that stores the semi-heated water, there is instead a tank right on the roof that stores the heated water. An electric heating element then adds the heat needed so there is hot water all the time and no water heater tank hanging around.

If a person lives in an area without natural gas, where electricity or propane or other fuels must be used for water heating, solar should be considered. Just remember the solar hot water from the roof is only a pre-heater as most of the time the roof tubing can not provide enough heated water for all household usage. So you’ll always need another fuel to finish heating that water to the desired temperature. PG&E may still be offering a rebate for adding solar pre-heat to an electric water heater. Check it out.

Electricity is still the most expensive way to heat anything, be it water, air, or wet clothes.