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0208 501 2100

0208 501 2100

A division of the ET Clay Group

What is Solar Energy

There are two forms of solar; 'solar thermal' and 'solar photovoltaic', which are commonly confused. Their similarities are that they both sit on top of a building's roof, and use the sun to create energy. However, they both create two very different end results.

  • Solar Thermal heats up water.
  • Solar Photovoltaic generates electricity.

It is important to start off by deciding which form of renewable energy is best suited to you. This page is to aid you with further information on solar panels.

What is kWp?

There are lots of words and phrases used with photovoltaic, which are easily mistaken. For example, photovoltaic is commonly referred to as PV. A second example is kWp vs. kWh. A kWp is a measurement given to a cell or module, on the maximum output at any given time, in test conditions. kWh is the measurement of electricity, or the kilo-Watt hours produced during a period of time. In the UK, it is commonly calculated, that a 1kWp system, will produce 850kWh per annum of electricity.

Will a 1kWp system always produce 850kWh?

No. 850kWh is based on the assumption that the pitch of the roof is 35 degrees, and the orientation of the roof is in a southerly direction. This is the optimum; however an eastern or western orientation is still capable of producing up to 85% of a southern orientation roof, assuming there is no shading.

Solar Energy 2

850kWh is also a figure used by SAP assessors (government building control) as an average figure across the UK. The actual figure will be increased in the South East of the UK, as there are higher levels of radiation in this region, compared to the northern counties.

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What constitutes, 'large amounts of shading'?

A PV installation should always avoid shading if possible. Eliminating all elements of shading on a domestic building is nearly always impossible. For example, roof dormers, chimney tops or even TV aerials can cause a small element of shading. The PV design should try to avoid installing PV at these areas on the roof.

Large amounts of shading which should be avoided should be large trees higher than the roof level, or other adjacent buildings blocking out sun light, or similar. A site survey should be carried out by your MCS electrician, prior to installation, to make you aware of any high elements of shading on your property.

Building Regulations

The Code for Sustainable Homes is a code set by the Government, and has two levels. The first level applies to Social Housing projects, and the second level applies to Private New Builds. The levels are set 2 years apart, with the private builds 2 years behind social housing.

The code for sustainable homes

The codes equate to different percentages of renewable required for a new build. For example, in 2010, code 3 is required for social housing, which requires 10% of the buildings energy to come from a renewable source. In 2011, this increases to code 4, where 25% of the buildings energy must come from a renewable source.

Come 2012, a private new build project, by government legislation, will be required to produce 10% of the buildings energy consumption by a renewable source.

What is MCS?

Solar energy approved product

MCS stands for the Microgeneration Certification Scheme, which is a government body to ensure that each and every photovoltaic installation is carried by an approved installer, with approved products.

What is the FIT?

The Feed-In-Tariff is a schemed used in over 40 countries worldwide successfully. It was introduced to the UK April 2010. The scheme is based on the government paying a photovoltaic system owner, a tariff for producing their own electricity. This is a huge financial reward for a photovoltaic system owner.

The contract with the government is set up for 25 years. With a payback region of 10-14 years, the remaining years will produce a financial income plus free electricity.

To be eligible for the Feed In tariff, the products must be MCS accredited, and the electrical commissioning works must be carried out by an MCS installer. To learn more about the FIT, click here.

Please note: All information provided within this document is an interpretation of the document entitled 'Consultation on Renewable Electricity Financial Incentives 2009' published by the Department of Energy and Climate Change.

All information is subject to change, and therefore Solar Cube Ltd cannot be held responsible for any action taken as a result of it. However, it is our aim to provide customers with information that is accurate.

Further information

If you would like to know more, or are interested in a quotation we would be happy to help. Telephone us on 0208 501 2100, email us at, or fill in our enquiry form, and we will be in touch as soon as possible.

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