Renewable Energy - Solar Photovoltaic (PV) Systems and the Feed in Tariff

by Nick 8. September 2011 19:15


Renewable energy is energy produced from free sources such as sun, wind, tide, animal and plant matter.

In order to reduce the carbon emissions of our country the Government is encouraging householders to invest in renewable energy sources by the introduction of incentives.


Photovoltaic (PV) systems operate by converting solar radiation into electricity. Photovoltaic panels most commonly contain crystalline silicone cells. These panels are set directed towards the sun and convert the sunlight into DC electricity, which is subsequently converted into AC using inverters.


Installation types - Panels are often installed on pitched roofs although they can also be fixed to frames on flat roofs or the ground. Pitched roof panels can either be installed ‘in-tile’ or ‘over-tile’. ‘The in-tile’ system requires the removal of tiles and the panels are set within the roof finish. This system is more expensive to install and less efficient (due to the lack of air flow around the panels), however it is less obtrusive. The ‘on-tile’ system is fitted over the existing tiles.


Production - Although PV systems are capable of producing electricity even on cloudy days, efficiency is dependent on the intensity of light falling on the panels. For optimum electricity production the panels should not be in shade and the best orientation is between south-east and south-west.


Feed In Tariff (FIT) – As an incentive to homeowners and developers the Government has set up an initiative called the Feed In Tariff (FIT).

The FIT benefits the owner in three ways:


  1. It guarantees a minimum payment for all electricity generated by the installed system. This is known as the Generation Tariff and is paid regardless of how much energy is put back into the national grid system.
  2. Payments are also made for any electricity exported to the grid once the household’s requirements have been met. The Export Tariff.
  3. Savings are made on the household bills as less electricity is purchased from the grid.


For a retrofit system less than 4kW the tariffs as of August 2011 are:-


  • Generation Tariff             =             43.3p/kWh
  • Export Tariff               =            3.1 p/kWh


These rates are subject to change each year for new installations eligible for the scheme, however once the rate for the system is set it should apply for 25 years for PV systems. Homeowners should check the rates and guaranteed payment period prior to placing an order.


Cost – The cost of installation will depend on a number of factors. Mitsubishi Electric have provided us with the following rule of thumb for an ‘on-roof’ domestic installation:-

£5k for the first kW and there after £3k for every kW.

Example: A 3.6kW system would cost in the region of  £12,800 to install.

The Energy Saving Trust suggests that these costs may be slightly higher at between £5k and £7k per kW installed.


Mitsubishi electric’s website contains some useful case studies including a property with a 3.6kW installation. The case study suggests that the system will generate over 3,000kWh per year and has the potential to earn the householder almost £1500 per annum taking into consideration the FIT and export income combined with the savings in electricity purchase.


Some things to be aware of when considering a PV system


  • Use an installer certified under the Microgeneration Certification Scheme.
  • Check the Installer is a member of the REAL assurance scheme.
  • Check the likely output of the chosen system meets your requirements.
  • Ensure that you will benefit from the FIT, check the rates and guaranteed period.
  • Ensure your proposed system is eligible for the FIT
  • As with all products, the quality of panels will vary dependant on the product manufacturer. Ensure your supplier is using a high quality panel and obtain product guarantees and expected life expectancy of the panels.
  • Maintenance of the systems is generally considered to be low. Take into consideration that the inverter may require replacement after 8-10 years.
  • With the FITs in place it would appear that Photovoltaic systems could be a good investment. The initial outlay can be significant and the investment is tied into the property. Individual customers should carry out their own research to ensure that the payback period and benefits of the system meet their requirements, as the return on investment is dependant on a wide range of factors.


Useful websites:-   - The Department of Energy and Climate Change       The Energy Saving Trust is a non-profit organisation that provides free and impartial advice on how to save energy.             Mitsubishi Electric – Product manufacturers

(this is a useful source of information however we are unable to recommend specific products as we have not experienced these products in use and do not know how they confirm to other products on the market)  - The Renewable Energy Centre


Nick Belderbos

For and on behalf of                                          September 2011


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