Is my house roof suitable for solar PV?

Ideally you need a space on your property that is south facing (South, South-East, and South-West), has no shading in summer or winter from trees, chimneys or neighbouring properties.  It doesn’t need to be the roof on your house; it could be your garage, an outbuilding or even on the ground in your garden.  

• Orientation: South facing roofs receive more radiation throughout the year and will produce the maximum energy output. The ideal roof will have an orientation 90° south. However South-East and South-West orientated roof will still produce high solar yields

A good way to determine the orientation of your roof is to view it on the google maps website.  Key in your postcode and you will see a satellite photo view of your property. That will allow you to see the orientation of your roof (North being the top of the page and south being the bottom)

• Latitude: Besides orientation the location of your property will also affect the output of your system. Southern regions of the UK receive higher annual irradiance and therefore are able to generate more electricity. Please click here to see a solar irradiance map of the UK
• Tilt of your roof: 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. The ideal tilt will have a 30° inclination. However, the inclination of the roof does not play such a decisive factor as orientation. For this reason roof inclination between 20 to 60° will be receiving most of radiation. Fortunately, the average tilt of a UK house roof is about the optimum for receiving solar energy.
• Shading: Shading would have a detrimental effect on the electricity your system generates. Shading may come from trees, chimneys or surrounding buildings. Shading is a very important factor in the solar PV output. However, if your panels are partially shaded at the early morning or dawn, the system will still generate acceptable yields.  Your installer will be able to assess and highlights any shading concerns and give you a realistic electricity generation potential

It is important to highlight that your roof does not need to meet all the above optimum requirements to still present a very profitable output.

The table below will allow you to estimate the percentage efficiency of your roof for a solar PV system based on orientation and tilt:

Efficiency map for solar PV installation as a function of angle of roof and roof orientation (Source Energy Saving Trust)

For a more accurate estimate of the electricity output of a PV system for your house you can use one of the many tools available in the internet. We recommend the tool designed by the European Commission tool to estimate the solar PV output based in a series of factors. You can access this tool here  

General requirements of a property

There are certain general requirements for any property to host solar PV panels. These are:

1. You own the freehold of the property – If you own a leasehold property, you’ll need permission from the freeholder and if you are renting the property, you’ll need written permission from the landlord.
2. Your property is not a basement or mid-floor flat.
3. Your property is not a listed building, nor is it in a conservation area – you don’t need planning permission for most home solar technology systems, but check first with your local planning officer, especially if your building is listed, in a conservation area or World Heritage Site.  This will require specific permissions.
4. You have an unshaded roof, outbuilding or garden space facing between east and west through south – Ideally a solar PV system should face between south east and south west, be free of shade and should be angled at 30 to 40° for optimal performance, although PV systems can still generate a reasonable amount of energy when angled between 20 and 50° even with a small amount of shading.
5. The roof is structurally sound – solar panels weigh approximately 12 kg each so a typical installation includinging mounting structures could weigh up to 250kg. The weight however is spread out across a large area so most roofs are capable of supporting them, but a roof survey may be a good idea.

Costs of Solar PV

Cost of a solar PV system

The cost of installation PV systems, in particular the cost of the panels is falling and is expected to continue to do so. The cost of PV equipment doesn’t vary much as there are only a few wholesalers in the UK, and variability in installation costs tends to be smaller than for other technologies

The Department of Energy and Climate Change (DECC) provides the following guide of costs.  For a 2kW retrofit system DECC assumes a fixed cost of £1,249, plus a variable cost of £2,542 per kW. The cost of solar modules continously decrease with technology development and a larger scale of production. For this reason we think these costs are now consierably lower than those provided by DECC in its “Solar PV cost update” as it was published in January 2012.

As a guidance example following DECC medium cost: 2kWp installation should therefore cost around £3,971.  See DECC’s website for source of costing

Governmental Grants and support

The main financial support scheme in the UK is the Feed-in Tariff Scheme (FiT). The scheme is available to all UK householders connected to the grid. FiT provides a fixed payment that will be guaranteed to the householder for a 20 years period. More details on FiT can be found below

If you would like to find out more about the Feed in Tariff Scheme or other available grant in your area please visit the Energy Savings Trust database.

How much electricity can a Solar PV system produce?

As a general rule, each installed kWp installed at the optimum angle can be expected to produce around 850kWh (units) of electricity per year in the UK, a 3kWp system would thus generate roughly 2,550 units per year. DECC assumes in its tariff calculations that consumers use approximately 50% of the generated electricity themselves.  As a typical 3 bedroom house will use between 3000 and 4000 units of electricity per year, a 3 kWp PV system could therefore provide more than a third of this demand.

Feed in Tariff (FIT)

Wha is it and how it works?

Click here to see our websites description of the FIT and to see the most up to date information on tariffs. 

The FIT forms part of a Government-backed scheme that pays people who create their own electricity using renewable technology, including Solar PV.

The Feed-In Tariff guarantees a minimum payment for all electricity generated by a solar PV system (the generation Tariff), as well as an additional payment for the unused electricity produced that can be exported to the national grid (the export tariff). These payments will further boost household savings as electricity bills will be reduced by using electricity generated on-site.

 The money received for both the Generation and Export tariff doesn’t come from the government, instead it is paid by the energy suppliers. The supplier passes on the cost of the Feed-In Tariff to their electricity customers, essentially making traditional energy consumers pay for those generating their own renewable electricity.

 The tariff is available to everyone and is designed for householders who install a renewable electricity system with a capacity of 5MW or less. In addition the payments are tax-free and index-linked (tariffs will keep on top of inflation), and will continue for a 20 year period. The FIT is overseen by Ofgem who regulate the electricity and gas markets in Great Britain.

How much can I earn?

Generation tariff

The generation tariff is a payment made by the energy supplier for each kWh of electricity your installation generates. This rate tracks inflation and will change each year, but once you join you will continue to receive the tariff for 20 years. The payment received depends on the size and type of technology you are using rather than a set rate. The good news is that the biggest payments come with solar PV technology with as much as 15.44 p per kWh available. You will receive a generation tariff for all the electricity generated by your solar system even if you consume part of it.

Export tariff

The export tariff is another payment for every kWh of electricity you generate but don’t use and then export to the national grid. The payment has a set price of 4.64 p per kWh. The tariff has been designed as an extra incentive to encourage people that they will still receive money for any surplus electricity they generate.

Consumption saving

 A part from receiving an income from the electricity that you generate and export, you will be consuming electricity generated by your system and buying less from the grid. This will cut the cost of your electricity bills. While homeowners only receive FITs payment for first 20 years of the system, PV owner will continue benefiting from using your own electricity for a minimum of 25 years installation life. 

Please click here to see a very short video explaining how FiT works Video on FiT

 According to the Government, these tariffs should cover the initial cost of the installation of the technology with a return of up to eight per cent over a 25 year period. You can calculate the potential financial return of a PV systems Solar Guide’s Solar PV Feed-In Tariff Calculator.

For example:

A Property in London with 10m² PV installed in its South facing roof installing a 1.5kWhp system will receive the following financial benefits:

Ø  Generate (@15.44p/kWh) : £194.80

Ø  Export (@ 4.64p/kWh): £38.15

Ø  Electricity bills saving: £63.75

Annual benefit: £296.70 

Financial benefits over the 25 years of the installation: £8,113 (20 years FITS & 25 years consumption saving. Inflation adjusted)

Approximate cost of the installation (Based on DECC’s figures): £3,971

You could get a tailored investment calculator for your future Solar PV system  by using the Energy Saving Trust Solar Energy Calculator which estimates the income and savings you could receive from the domestic Feed-In Tariff scheme. Please click here to access the EST calculator

How is my electricity generation measured? As the tariff payments are based on kWh’s produced and exported, the energy generated needs to be measured. A meter needs to be installed to measure the three energy flows; generation, import and export.

You will already have an import meter which is used to calculate your energy bills. Some of these are capable of measuring export too, but this will need to be investigated. A generation meter will be provided with whichever MCS certified product you choose to have installed.

How do I apply for FIT payments?

In order to claim for FIT payments from a Utility Service Provider (USP), you will need to provide your supplier with the Microgeneration Certification Scheme (MCS) of your PV installer and MCS accredited product must also be used.

Once the installation is complete you will receive a pack containing all of the relevant information about your system, including an MCS and FIT eligibility certificate from your installer when the work is finished. The supplier will then cross-reference your installation with the central FIT database and cleared payments will begin to be paid to you at intervals decided between you and the supplier. In most cases the FITS payment is made by personal cheque to the person named on the household utility bill every quarter.

Choosing an installer

 It is important to choose a reliable and trustworthy installer, to help customers make an informed decision a certification scheme has been introduced for both installers and products on the market, known as the Microgeneration Certification Scheme (MCS). In the process of becoming MCS accredited, installers wishing to sell or lease renewable energy products must sign up to a consumer code such as the REAL assurance scheme.

The STA website provides a list of installers. To find a local installers simply use the “Search by Company Type” then select “Installer” and type your postcode

In order to claim your FiT your installer will need to be MCS accredited. You can check whether your installer is MCS accredited here. The best advice is to ensure you get 3 different quotes from installers before you choose your installer 

Further information for householders:

EST (Energy Saving Trust) is a charitable status organisation aimed at giving impartial, accurate and authoritative advice on how households can reduce their carbon emissions and help people save money on energy bills.

REAL: The REAL code was created by the Renewable Energy Association with the aim to guarantee a high quality experience for consumers wishing to buy or lease small-scale energy generation systems for their homes.

Companies that receive REAL accreditation have signed to commit with the REAL code of practices and therefore offer a guarantee to customers that companies will operate within an ethical conduct. (MCS must be REAL) STA are REAL

Which?: As a consumer champion, Which? provides advice to help consumers make informed decisions. Please check the “How to buy solar Panels” guide