We all like hot showers, hot dish water, hot water to wash our clothing and even a hot cup of instant tea. Well solar energy can provide most or even all of that hot water for your home. In use in America since the 1920’s, active solar water heaters are a no-brainer in some areas of high sunlight (i.e. desert Southwest, Florida, etc.) but make sense just about anywhere in the United States.

In terms of solar energy applications, solar water heating is the most inexpensive and effective. Active systems can range up to $6,ooo or higher depending on size, but they can also fall under $2,000; and federal and usually state tax incentives and rebates can drop that price by 30-50% and sometimes more.

So how do you get active on your active solar water heating system? First you’ll need to know a bit about them.

The Collectors

Solar energy collectors for hot water systems come in three different designs: flat-plate, evacuated tube and integral collector storage (ICS), the latter relegated to passive solar water heaters. By far, the most popular choice is the flat plate collector, which involves a flat metal plate, painted black to absorb sunlight, resting beneath a sheet of glazing. Beneath this plate runs tubes containing cool water or a transfer fluid that collects in turn the heat that the plate has collected.

Evacuated tube collectors come in a few variations, which you can explore here. They all, however, follow the basic premise of metal (usually copper) fins or tubes running up and down inside a larger collector tube. These metal fins absorb the heat caught by the larger collector and a transfer fluid travels through the tube, in turn takes the heat from the metal absorbers and transfers it to the water within a storage tank. While all these steps seem unnecessary, evacuated tube collectors are able to reach much higher temperatures (often too high) than their counterparts.

In all cases an electric pump (powered by solar photovoltaics or conventional sources) is used to move liquid and/or water throughout the collectors.

How Active Hot Water Systems Work

The two main components of an active solar water heater are the collectors and storage tank, supplemented by a pump or pumps and a heat exchanger for those using an anti-freeze transfer fluid. Note that most U.S. solar hot water heaters use a closed-loop, transfer fluid system because of the dangers of freezing in winter. Storage tanks will vary in size depending on a home’s hot water needs.

Essentially the system works as follows: First the fluid is pumped up into the rooftop collectors where it is heated. It is then sent through a heat exchanger typically attached to or near a storage tank where that heat is passed on to the home’s water supply. From the tank the hot water can be drawn by demand into the house.

Tankless solar water heaters are very much possible and many are in use. The advantage of having a storage tank, however, is that hot water can be made available at night as well. For this reason, water storage tanks are heavily insulated and located indoors (often right next to a conventional water heater used as backup when the solar collectors aren’t collecting).

Solar hot water heaters can be connected directly into your existing water system and, besides the extra tank, do very little to upset life within the home during installation. To learn more about installing an active solar hot water system at your home, get no-hassle free estimates, as well as enlightening conversation, with local solar thermal installers.

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Posted on July 22nd in Solar Information by Dan.