Solar panel systems and components

Solar water heating uses heat from the sun to provide hot water. This form of energy is free and when used in a tyical household could save between 12-17% of annual fuel costs.

How does it work?

The process of solar water heating involves the absorption of the suns radiation by collectors, via a fluid (usually water and/ or antifreeze), and the transfer of the heat to a hot water storage tank. This is then made available through the buildings hot water system. There are two main types of solar collector for solar water heating: Flat plate and evacuted tube collectors. Some flat panels are designed to be almost unnoticeable, by being flush to the roof whilst evacuated tubes are more conspicuous. The tube collector is however, more advanced and more efficent but also more expensive. A third type, called unglazed collectores are cheaper and used for swimming pool systems.

Solar panels work best when they are placed at an angle of 30-40deg from horizontal and are facing due south. Evacuated tube systems have greater flexibility and can face south to west because of the greater surface area of their collectors. Solar water heating systems also work in cloudy conditions.

Solar panels can be fitted in conjunction with combination (combi) boilers to provide pre-heated water and thereby reduce the energy needed to bring the water to the required temperature. However, this requires slightly more expensive installations and space for a small 100 litre hot water cylinder.

Can I produce all my hot water with this technology?

No. A typical system will provide virtually all your hot water in the summer and about 50-70% of the year round demand. For example , a dorset house witha south facing roof inclined 30 degs will recieve between 1100-1200 kilowatt hours (kWh) of solar radiation per square metre per year. About 40-50% of this can be converted to hot water by a solar collector so a 4mSq array will produce around 1800kwh of heat, which is equivalent to 60% of domestic hot water needs. There is a big difference in the solar energy available throughout the year as a rule  solar collector will provide 80-100% of the hot water during the height of the summer and perhaps as little as 15% in the depth of Winter.