Solar Energy - The UK's large solar energy resource
Solar energy in the UK is far greater than most people imagine. In the summer, when items such as car bodies are often too hot to touch we become aware of the Sun's heat. However, even in the spring and autumn and on clear winter days we receive very useful amounts of solar energy.
By tilting a surface to an angle the amount of solar radiation falling on it will be greater than that falling on a flat surface in this country.
Fortunately, the average tilt of a UK house roof is about the optimum for receiving solar energy in the UK.
NB. The average property requires approximately 3,000 kWh per year for domestic water heating.
UK solar irradiation
Annual Total kWh/m2
Fig 1.: map showing average solar radiation on a 30° incline facing due south
Fig 1 shows the total average solar radiation falling on one square metre surface inclined at 30 degrees to the horizontal, measured in kilowatt hours.
These figures bring out the remarkable fact that the amount of solar energy falling on the total roof area of an average house is many times that required to provide all its heating and hot water.
However, we must note that there is a large difference between the radiation available in the summer and that available in winter; also Active Solar Heating systems will typically convert 40 to 50% of the solar energy falling on the solar collectors into useful heated water. These factors must be taken into account in determining the optimum size for a system.