Solar Water Heater Principle

Shallow water in a lake is usually warmer than deeper water. This allows sunlight to heat the shallow water, which in turn heats the lake bottom. This is the natural method of solar water heating. Solar water heating can be constructed and used in essentially the same way as for a swimming pool. Solar Water Heater

Most solar water heating systems for buildings have two main components: a solar collector and a storage tank. The most common collector is called a flat-plate collector. It is a thin, flat, rectangular box with a transparent cover that faces the sun and is installed on the roof. Small tubes run through the box, carrying water or other liquids—such as antifreeze—to be heated. The tubes are connected to an absorber plate, which is painted black, to absorb the heat. The heated fluid passes through the collector and accumulates heat in the pipes.

Then, a tank holds the hot liquid. It may be a modified water heater, but it is usually large and well-insulated. When using a fluid other than water, the system typically involves heating the water in a tank filled with hot fluid through coiled tubing.

Solar hot water systems can be active or passive, but the most common is the active system. While passive systems rely on gravity and the natural circulation of water to heat it, active systems rely on a pump between the collector and storage tank to move the liquid.

Swimming pool systems are easy. A pool filter pump is used to pump water through the solar collector, which is usually black plastic or rubber. Of course, the pool stores the heated water.