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Solar Water Heating

Solar panels contain water that absorbs heat from the sun. They are usually fitted to the sunny side of your roof, or you can sit them on a purpose-built stand. As a rule of thumb, you need about a metre of panel per person.

Once the water in the panels is hot it travels to a coil in a hot water tank, where it transfers its heat to the water in the tank – this is an indirect system. In a direct system hot water from the panels goes straight into a cylinder, but it is unsuitable for use in hard water areas.

Hot Water
Solar panels should supply most of the hot water for an average household for the sunniest four or five months of the year. In winter they make a much smaller contribution to hot water, especially in the UK! Averaged over a whole year, you can get about half of your hot water from solar panels.

Solar water heating is an excellent way of cutting back on your fossil fuel consumption, since most traditional methods of heating water are reliant on burning some sort of fossil fuel. It is also a great way of saving money – a good solar heating system will pay for itself in its lifetime.

If you have the kind of boiler that heats water in a cylinder, then solar panels can be added to it relatively easily. It is more difficult to add solar heating to a ‘combi’ boiler – the sort that doesn’t heat water in a tank, but heats it on demand. Having said that, some of the latest designs in combi boiler will accept pre-heated water from solar panels. If you are fitting a new boiler and you’d like to have the option of adding solar panels, then make sure you check feasibility with the manufacturer before you decide on a model.

Not Enough Heat
In almost all cases in Britain, solar water heating won’t provide enough heat to warm you house. So you will always have to have a conventional water heating system on top to supply hot water for your own use and for your radiators in winter.

There are two main types of commercial solar panel available - flat plate and evacuated tubes. Evacuated tubes are the most efficient but they are more expensive and you may not get your money back within their lifetime.

You could be looking at a cost of £2000 to £4000 for a flat bed system and an equivalent evacuated tube system might set you back £3500 to £5500. Prices will vary depending on the size of the system and ease of installation. It is worth investigating the possibility of grants to help with the initial layout costs of solar heating.

Find out more
Low Carbon Buildings Trust: for UK Grants
www.lowcarbonbuildings.org.uk

Energy Saving Trust: information on solar heating
www.energysavingtrust.org.uk

Solar Trade Association
www.greenenergy.org.uk