They mainly consist of a water tank, a solar panel, and some pipes. The water tank feeds cold water through the Solar panel (warming it up), and then goes back into the tank, over and over. Eventually you are left with lots of warm water. The type and complexity is mostly determined by the changes in temperature in the day-night cycle, changes in temperature and solar radiation between summer and winter, and the temperature of the water required for the system. The minimum effiency of the system is determined by the amount or temperature you will need in winter (the most) and the maximum is determined by the need to stop water overheating (boiling, even).
The two main catogeries of solar water heating are passive and active. Passive use convection or heat pipes to circulate water, while active use a pump. In addition, there are a number of other system characteristics that distinguish different designs, such as the type of collecter, the location of the collecter (roof mount, ground mount or wall mount), the location of the storage tank relative to the collecter and the way the heat is transferred. Also, some versions can get electricity and hot water.
Normally (for standard solar heating), you would have to make sure your roof is strong enough, and can take the extra weight. You also have to make sure that the building regulations apply to it. Sometimes, you will have to ask your local council to look and agree that the Building Regulations apply as well.
Prices range, but you usually pay about £3000, maybe more. Because of the price many people buy Do-it-yourself kits. They are sometimes cheaper, easy to install and do about the same as a standard one. However there is still the cance of something going wrong, so it is a good idea to thoroughly read the instruction manual.
Passive and active require different maintenance. A passive system requires no regular maintenanance, as it has no electrical or mechanical parts that will break. The effiency is a lot lower of it, though, but overheating is largely avoided with the design of it. Active, on the other hand, can tolerate higher temperatures than a passive. As a result, an active is much more efficient, than a passive, but cost more, are more complex, more difficult to instal and require a mains or PV sourced electricity to run the pump and controller.
In colder climates, some systems require anti-freeze, and some systems come built in with freeze tolorent tanks.
Say a system cost you £3000, if you saved the equivalent of 140 units of electricity per month, then over a period of ten years you should get it all back. After this, you should save fifteen quid per month, depending on region. In Florida, you can get your money back in an average of six years.
15 Apr 2011
21 Apr 2007