Solar water heaters – also called solar domestic hot water systems, or solar thermal systems can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use – sunshine – is free.
How They Work
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t. Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.
Two main types of solar collectors are used for residential applications:
Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plates, sometimes with a selective coating,s under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors—typically used for solar pool heating—have a dark absorber plate, made of metal or polymer, without a cover or enclosure.
Evacuated-tube solar collectors
These feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin’s coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently in cooler northern climates due to their higher efficiency when the air temperature is lower.
Case Study – Mr. Stephen E., Estepona using a pressurized flat-plate system.
Stephen contacted Pretasol Energia to look at installing a solar hot water system in his villa near Estepona. A site survey ascertained the most suitable solution – a 300 litre system with the panels on the roof and the water tank inside the home would offer the most efficient and aesthetically pleasing solution. The system was up and running soon after providing sun powered hot water to the house and Stephen commented: “Pretasol completed the installation within four weeks and also secured the grant to help cover some of the cost. Based on meter readings following the installation we are already seeing a 45% reduction in our electricity bills and are looking forward to a payback in less than two years.”
Hot water consumes about 30% of the average household energy bill according to the Junta de Andalucia. As natural gas production declines and prices climb the cost of hot water is expected to rise dramatically. Retrofitting a home for solar hot water could save a lot of money and also help to alleviate the strain on the energy production cycle as a whole.
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