Solar PV

Electricity generation from solar panels

Solar PV (or photovoltaic) is a technology which generates electricity from sunlight.   A solar PV system consists of a series of solar panels (usually made of silicon), an inverter which converts the DC electricity generated by the panels into AC electricity which can be used in the home, a generation meter and a set of AC and DC isolator switches for protection.

The amount of generation from a solar PV system depends on the location, orientation, angle of inclination and level of shading.  In general, the generation is higher for more southerly locations in the UK, but the local geography does also affect the level of sunlight.  The optimum orientation and angle of inclination for a system is facing south and inclined at about 35 degrees.  Satisfactory performance can be still achieved with a solar PV system split between an East and West facing roof.  Although the annual generation would be lower for such a system, there are benefits since more electricity is generated in the morning and late afternoon, times when it is more likely to be consumed.  Shading of a solar PV system due to trees, hills or other buildings can significantly reduce the annual generation.

Feed-in Tariffs

The price of solar PV systems significantly decreased over the last few years due to the introduction of Feed-in tariffs which have stimulated demand in the UK and abroad and has increased production of components and the number of installers.  With the Feed-in tariff system, you are paid for every kWh your solar PV system generates.  You can also consume whatever electricity you generate for free and you are paid a generation tariff for the remaining amount of electricity that is exported to the grid.

The feed -in tariff for a domestic solar PV system was initially over 40p/kWh, however since then, there have been a number of tariff reductions and the rate is now under 15p/kWh.  There are now regular tariff reductions of 3.5% every 3 to 9 months.  Larger solar PV systems have lower feed-in tariff rates as can be seen in the table below.  The most up to date rates can be found on the Ofgem website.

For systems below 30kW, for the purpose of calculating payments, it is estimated that 50% of the electricity generated by the system is exported to the grid.  For installations above 30kW, the system owner is required to have an export meter, which measures the amount of electricity the system exports to the grid and payments are based on this meter reading.  An export meter will cost several hundred pounds.


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