Solar Panels for Hot Water

In most circumstances solar panels are used to produce domestic hot water (DHW) rather than space heating. In a super-insulated house with good airtightness it is possible for solar panels to contribute to space heating as well, as the heating requirement is so low. In this case we are looking at producing DHW only.

Solar panels come in two forms: flat panels and evacuated tube, and largely it is a matter of paying your money and taking your choice. Evacuated tubes are said to be more efficient and flat panels cost less. On balance there is no material difference. It is more important to find a good, trustworthy supplier than to find the best possible deal.

Flat Panel: Typically these are supplied in panels of 2m² to 2.5m², varying with the manufacturer, and a system for the typical four bedroom house with four people living in it will cost about £3,500 installed including a hot water storage tank. A flatpanel system of this size will generate around 60% to 70% of the annual DHW demand. They can be roof integrated, meaning that they replace the roof covering, but they can only be sized as multiples of panels — 2m², 4m², 6m², etc.

Evacuated Tube: Typically supplied in groups of five or six tubes — thus, six, 12, 18 tube systems, and so on, giving more flexibility in sizing. A typical system will cost £4,200 to £6,000 installed including a hot water storage tank.

“Solar panels have halved our hot water bills”

John and Joan Barnes installed solar panels on their self-built eco house in Dorset. They plan to spend the rest of their retirement here, so longterm savings were a priority. The panels cost £1,800 but cut hot water costs in half... Read More

Further Reading:

• Saving Energy: A Look at Renewables
• Solar PV for Electricity
• A Guide to Green Technology