Renewables: Solar Water Heating Systems

Solar water heating systems use heat from the sun to work alongside your conventional water heater. The technology is well developed with a large choice of equipment to suit many applications. Last year the UK's leading DIY retailer, B&Q began selling solar water heating systems at their stores and online.

By installing solar water heating systems to your home you will help to reduce your energy consumption for heating water, some systems can currently provide up to 70% of your hot water needs, almost 100% all during summer months. This not only will save you money but reduce our dependency on fossil fuels which are conventially used to provide the energy in our homes to heat water. A basic solar water heating system will reduce your CO2 emissions by about 400kg per annum. Solar hot water systems generally come with a 10-year warranty and require very little maintenance. A yearly check by the householder and a more detailed check by a professional installer every 3-5 years should be sufficient.

For domestic hot water there are three main components;

• Solar panels or collectors - are fitted to your roof. They collect heat from the sun's radiation.
• There are 2 main types of collector:
  Flat plate systems - which are comprised of an absorber plate with a transparent cover to collect the sun's heat, or
  Evacuated tube systems - which are comprised of a row of glass tubes that each contain an absorber plate feeding into a mainfold which transports the heated fluid.
• A heat transfer system - uses the collected heat to heat water
• Hot water cylinder - stores the hot water that is heated during the day and supplies it for use later.

There are many applications that a solar water heating system can be used for, including within the home, businesses and swimming pools. You will need 3-4 square metres of southeast to southwest facing roof receiving direct sunlight for the main part of the day for a domestic system. You'll also need space to locate an additional water cylinder if required.

Choosing a system suitable to your needs requires consideration of a range of factors, including the area of south facing roof, the existing water heating system (e.g. some combi boilers aren't suitable) and your budget. A competent accredited installer will be able to assess your situation and discuss with you the best configuration to meet your needs.

If you are interested in installing a solar hot water system, typical installation cost for a domestic system is £3,000 - £4,500. Evacuated tube systems tend to be more expensive, however grants are available from the low carbon buildings programme (funded by the Department of Trade and Industry, DTI). To be eligible for a grant you will need to use a certified installer and products. The low carbon buildings programme offers a maximum of £400 or 30% of the relevant eligible costs, whichever is the lower for solar thermal hot water systems.

Related Links

Low Carbon Buildings Programme
Department of Trade and Industry
Certified Installers
Certified Products