Solar panels usually are of two broad-based types – Solar panels with photovoltaic cells that generate electricity and those that are used for heating. We are here to discuss the latter type which have several sub-groups that all cater to heating water. With a view to heating water using solar energy, a collector is attached to the roof of a building or on a wall facing the sun. The working fluid is either driven by natural convection as in a case of ‘passive system’ or is pumped into it as in an ‘active system’.
Also, the collector could be made of glass-topped insulated box with a flat solar absorber made of sheet metal attached to copper tubing and painted black or a set of metal tubes set within a near vacuum container.
An ‘active system’ solar water heating arrangement would pump cold water onto a collector to be heated that flows back to the collection tank for use later on. This type of collector provides enough hot water for an entire family for several years.
Sometimes, heat is stored in a hot water tank whose volume must be larger with solar heating system to allow excess for inclement weather conditions as also for the simple reason that the optimum temperature for the absorber is always lower than a typical immersion heater or a combination heater.
Here are a few types of solar heating panels
1) Evacuated-tube solar water heating panels are recommended for cold climates. They have parallel rows of transparent glass tubing, each provided with outer tube and a metal absorber tube attached to fins or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder. Often before the solar energy is absorbed, a parabolic mirror is put into use to concentrate rays of the sun on the tube.
2) Integral collector-storage solar water heating panels are good for locations where the weather is moderate to warm. These include several black-painted tanks or tubes within insulated and glazed box. Here the water initially passes through the solar collectors in the solar panel that pre-heats the water. It is then allowed to pass into the conventional backup water heater, thus providing a good source of hot water. The progressive Tube passive system, incidentally, is the most cost efficient water heater.
3) Unglazed collector panels are ideal for pools and are suggested for locations that have above-freezing climates. Instead of glass (glazed) coverings, these are usually made of heavy-duty PVC or rubber treated with UV protecting material to extend the life of the panel. Unglazed collectors are more cost effective than glazed ones.
Home solar panels or commercial solar panels, there are many advantages of both. You can save on your electricity bills and this is eco-friendly as well. But before you can go solar you need to know a few things – where to set up a system, how to install it, how to wire it, where to get parts and batteries from cheaply, and finally the safety precautions.