Types of Solar Hot Water Systems
All types of solar hot water systems work simply by putting water in a place where the sun can heat it. There are two types of water heaters:
Flat Plate Collectors (using water in pipes)
Batch Collectors (water in tanks.)
Flat Plate Collectors circulate water through black pipes housed in a special panel. This panel has glass on top for the sun's light to shine through, and is insulated on the bottom and sides to prevent heat from escaping. Sometimes the water is heated directly, and sometimes another fluid such as antifreeze is used. This other fluid then transfers its heat to water via a heat exchanger. Flat plate collectors are better suited to larger houses or pools, as they can supply large amounts of hot water.
A Batch Collector is simply a water-filled tank, painted black and insulated by glass. The black outside of the tank allows heat to be absorbed more easily. The glass insulation prevents heat from escaping from the tank. Batch collectors tend to be more reliable and cost effective as they have no moving parts, pumps or controls. They use the house's water pressure to move water through the system. One thing to consider is that the roof may need strenthening depending on the size of the system.
There are many other categories of solar hot water heaters. However, they all use this same basic principle - solar energy creates hot water.