Key Facts

Fact! - solar power really, really works in the UK

There is lots of information regarding solar energy available to those that search but not all is factual – some is hearsay, some is opinion-based and some is sales talk. So here we have gathered together just facts so that you can make up your own mind.

Solar Energy generally refers to solar thermal (used to heat water – for hot water in your home or to heat swimming pools) and solar PV (Photovoltaic – used to generate electricity to power any electrical item).

Solar PV - Solar Electricity

For Solar PV systems to be effective you do not need full sun. Power will be generated in any weather as long as there is daylight. However, the greater the intensity of sunlight the more power is generated. So a system will work at its maximum capacity on a bright sunny day and will not work at all at night!

For an installation to be effective you do need a South facing (south west through to south east) aspect but this does not need to be the roof of your house. It could be the roof of any building – garage or outbuilding or it could be an area of land or garden suitable for a ground mounted installation.

Shading will affect the power output so you need to keep any nearby trees well pruned so that they do not shade the panels.

Savings can be considerable - upwards of 1.2 tonnes of CO2 a year. The bigger your system the more you save. A 2 kWp system could provide around half of a household's yearly electricity needs.

Maintenance is generally small - panels need to be kept relatively clean (rainwater generally does the trick!)

Considerations. The minimum space required for a solar PV installation is 12sqm. This will provide enough room for a 1.5kWp system. For larger systems you will require 8sqm. for each additional kWp fitted. So for example a 3kWp system will require 24sqm. of space.

Getting Paid for the Electricity you Produce. As a green generator of electricity you can get paid for the electricity you generate even if you use it all yourself! Rates vary by operator.

Solar Thermal - Solar Hot Water

There are two different types of Solar Thermal collectors (panels). Flat plate and Evacuated Tube collectors. Flat plate collectors use the heat of the sun to generate hot water whereas Evacuated Tube collectors use sunlight to generate hot water. So, here in the UK Evacuated Tube collectors will operate effectively in colder conditions such as a bright winter’s day, whereas Flat Plate collectors will not.

To work effectively panels need to face the sun so a South facing (south east through to south west) aspect is best, though solar thermal panels in an East or West facing aspect work as well. For domestic hot water heating panels are normally installed on the roof. For swimming pools – they can be either roof or ground mounted.

Shading will affect the power output so you need to keep any nearby trees well pruned so that they do not shade the panels. However, shading with solar thermal is not as important as it is with solar PV.

Savings are good - a solar water heating system can provide about a third of a typical household’s hot water needs, reducing water heating bills by between £55 and £95 per year. It will also save up to 645kg of CO2 emissions, depending on what fuel is being replaced.

Maintenance costs are very low. Most solar water heating systems come with a 5-10 year warranty and require little maintenance. Panels should be looked at every year and then checked more thoroughly by a professional installer every 5 years or so.

Considerations: The minimum space required for a Solar Thermal installation is 3-4 sqm. of roof space. A larger, or an extra, hot water cylinder may also be required. Most boilers are compatible with a solar thermal system but combination boilers with no hot water tank may not be suitable.

Power Generated

The power that systems output is measured in kilowatts (kW) or kilowatt hours (kWh). A kilowatt is the power generated at midday on a sunny day – this is also referred to as kilowatt peak (kWp). One kilowatt hour is enough electricity to power 95 low energy light bulbs for one hour. Electricity bills report electricity consumption in kilowatt hours (kWh).

The average house uses approximately 3,500 – 4,000 kilowatt hours (kWh) of electricity a year. Most household Solar PV systems are between 1.5kWp and 3.0kWp. For example a 2.0kWp system in Devon has generated 2,000 kilowatt hours (kWh). A 2.0kWp system in Birmingham has generated 1500 kilowatt hours (kWh). The difference in output is mainly due to the difference in the intensity of the sun.

Planning Permission

In England, installation of a Solar PV or Solar Thermal system is considered permitted development and therefore planning permission is not required. This does not apply if your property is listed, or situated in an Area of Outstanding Natural Beauty, Conservation area or World Heritage Site. Wind turbines normally do require planning permission. This is just a general guideline and you should always check with your local planning department.

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