Solar water heating systems use free heat from the sun to warm domestic hot water. A conventional boiler or immersion heater is then used to make the water hotter, or to provide hot water when solar energy is unavailable.
How do solar water heating systems work?
Solar water heating systems use solar panels, called collectors, fitted to your roof. These collect heat from the sun and use it to warm water which is stored in a hot water cylinder.
There are two types of solar water heating panels: evacuated tubes and flat plate collectors.
Flat plate collectors can be fixed on the roof tiles or integrated into the roof.
A boiler or immersion heater can be used as a back up to heat the water further to reach the temperature set by the cylinder's thermostat when the solar water heating system does not reach that temperature. (The cylinder thermostat should be set at 60 degrees centigrade.)
Larger solar panels can also provide energy to heat your home as well - though usually only in the summer months when home heating is unnecessary.
What are the benefits?
Hot water throughout the year: the system works all year round, though you'll need to heat the water further with a boiler or immersion heater during the winter months.
Cut your bills: sunlight is free, so once you've paid for the initial installation your hot water costs will be reduced.
Cut your carbon footprint: solar hot water is a green, renewable heating system and can reduce your carbon dioxide emissions.
Is a solar water heating system suitable for my home?
To find out if solar water heating is right for you, there are a few key questions to consider:
Do you have a sunny place to put solar panels? You'll need around 5 square metres of roof space which faces east to west through south and receives direct sunlight for the main part of the day. Alternatively, if you do not have a south facing roof and if you have space, you could install two panels, one facing east and one facing west - but this will make installation more costly. The panels don't always have to be mounted on a roof, they can be fixed to a frame on flat roofs.
Do you have space for a larger, or an extra, hot water cylinder? If a dedicated solar cylinder is not already installed then you will need to replace the existing cylinder, or add a dedicated cylinder with a solar heating coil.
Is your current boiler compatible with solar water heating? Most conventional boilers and hot water cylinder systems are compatible with solar water heating. If your boiler is a combination boiler (combi) and you don't currently have a hot water tank then a solar hot water system may not be compatible.
Do you need planning permission? In England most solar water heating systems don't need planning permission, but it is always best to consult your local planning office if you live in a Listed Building, or a building in Conservation Area or World Heritage Site. If you live in Wales, Scotland or Northern Ireland you will need to consult your local authority.
Costs for a typical solar water heating system is around £4,800 (inc. VAT at 5%).
Savings are moderate - a solar water heating system can reduce your water heating bill by between £50 and £80 per year. It will also save up to 570kg of CO2 emissions, depending on what fuel type you will be replacing.
Maintenance costs are very low. Most solar water heating systems come with a 5 -10 year warranty and require little maintenance. You should take a look at your panels every year and have them checked more thoroughly by an accredited installer every 3-5 years, or as specified by your installer.
For more information on home energy generation technologies, contact your local Energy Saving Trust Advice Centre free on 0800 512 012, or visit www.energysavingtrust.org.uk.