How Much Energy Does Solar Thermal Save?

What is Solar Thermal and How does it Work?

Solar water heating, otherwise known as solar thermal heating, works by collecting the sun's rays and converting these into energy to heat water. Solar thermal heating can be used in public buildings and swimming pools, but most commonly domestic homes.

Solar panels are fitted to a building, usually a roof, as they work well if fitted at an angle. The recommendation is 20-50 degrees from horizontal. The panels are connected to a specialist hot water cylinder which is designed for solar thermal use.

The solar thermal panels will harness the rays from the sun and convert them into energy. This is then pumped through a specially fitted coil down to the cylinder. This will then heat the water so that it is ready to be used in the household. As the energy is produced by the sun, the household will be less reliant on traditional energy such as gas or electricity, therefore reducing costs.

Will it be Suitable for my Home?

Solar panels can be fitted to most domestic dwellings, with the exception of houses with thatched roofs. If you have a listed building, or live in a conservation area, you will need to apply for planning permission. You will need to have a roof that is unobstructed, for example by overhanging branches from a tree, or excessive shadow from neighbouring buildings. The panels will work at their best on a south facing roof, however, a roof which is east or west facing will also be suitable. It is advisable to have space of at least 4-6 metres squared for the panels. Some guidelines suggest a minimum of 1-2 metres squared for each person who lives in the house.

How much Hot Water will it Produce?

Solar thermal panels will produce the majority of your hot water in the summer months, usually April to September. The panels work well in the summer due to both the sunlight and the longer daylight hours. During the winter months, you are likely to need a back up system to your boiler in order to supplement the hot water. Results from a recent survey of households using solar thermal show that overall the average household is likely to have 60% of its water heated by solar thermal.

How much Energy will this Save?

A household without solar thermal heating will usually rely on gas or electricity to warm their water. The electricity will be used for an immersion heater. Electricity will still be required in order to provide power to the pumps. However, the energy used for this is relatively small compared to the amount of hot water supplied by solar.

Solar thermal panels cost an average of £4,000 to be fitted. A typical household should expect to see savings of approximately £55 per year off their gas bill, but the highest savings can be made if you are converting to solar thermal heating from an electric water heating system. In this instance, savings of approximately £80 per year can be made.

It is important that the cylinder and the pipes which carry the hot water are well insulated. This will need to be discussed at the time of installation of the solar thermal system. The Energy Saving Trust have calculated that a household will save approximately £40 per year by having a properly insulated cylinder, using a 75 mm thick cylinder jacket. Also, a saving of £15 per year can be made by adding insulation to the pipes.

The Energy Saving Trust concluded from their recent survey that the majority of households using solar thermal were satisfied (84%) and that this system was a good, long-term investment.

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