What is PhotoVoltaic (PV)?
PV is the name given to solar panels that use energy from the Sun to generate electricity, which can then be used to power lighting and appliances within your home. PV uses daylight to create electricity and so does not need direct sunlight to operate. If you own a calculator it is very likely that you already own a PV system, as most modern calculators are powered by a small PV panel. As well as generating electricity for use in your home, PV can also be used to power small appliances such as torches and bike lights and can even be used to charge mobile phones and iPods!
The technology
PV panels are made up of cells containing 2 or more layers of a semiconductor material (usually silicon). When daylight reaches the cell an electric field is generated between the layers creating a flow of electricity within the cell. As the intensity of the sunlight falling on the cell increases, it causes the flow of electricity within the cell to increase.
There are 3 types of PV cells; monocrystalline, polycrystalline and thin film. Monocrystalline cells are made from thin slices of silicon which are cut from a single crystal. The typical efficiency of this type of PV cell is around 15%, meaning that approximately 15% of the light that reaches the cell is converted into electricity. Polycrystalline cells are thin slices which are cut from a block of silicon crystals (rather than a single crystal). This system is less efficient than a system using monocrystalline cells and has an efficiency of around 12%. The least efficient systems are made up of thin film cells. Thin film PV cells consist of a metal or glass base covered with an extremely thin layer of semiconductor atoms. This type of PV cell is around 7% efficient.
These cells are joined together to form modules which are then linked to form a solar panel (also known as a PV array). This panel is then used to supply the property with electricity, either directly (if the building has a mains electricity supply) or by charging batteries (for properties not on the mains electricity grid). PV arrays come in a variety of forms including panels and tiles (which can be used to replace existing roof tiles) and can be the traditional blue colour, grey or even transparent (for use on conservatories).
Typical domestic PV systems are in the range of 1.5 – 2 kW and will provide around half of the property's electricity needs. A system of this size would comprise of an array around 10-15 square metres and it is important to consider whether your roof is strong enough to support the weight of the panels (the Building Control or Planning Department may be able to advise on this matter).
It should be noted that most average-sized systems will not supply all of the electricity to meet your needs and, as a result, you will need to ensure that your existing electricity supply is maintained. In times of high electricity production it may be possible to sell any ‘extra’ electricity that the system generates back to one of the energy supply companies. More
details on selling energy back to the grid and switching your existing electricity supply to a renewable or green tariff can be found in the energy efficiency section later in the pack.
As with solar hot water systems the siting and orientation of the panels needs to be taken into consideration. Please see choosing the right technology and planning issues pages of this website for more information.
Life span and warranty
Warranties for photovoltaic systems vary from around 10 years right up to 25 years with some manufacturers. If your PV system is connected to the mains grid then it will require little maintenance. It is important that the panels are kept fairly clean (to maximise their efficiency) and a qualified installer or technician should check the wiring and general working order of the system on an occasional basis. For ‘stand alone’ systems other components of the PV system (such as batteries) may need more frequent checks and an accredited installer will be able to advise you on these considerations when estimating the cost of your system.
Cost
The Department of Trade and Industry currently give average system prices as £4000 to £9000 per kW, although solar tiles may be more expensive. If you are carrying out major roof repairs then solar tiles may prove a more cost effective option, and an accredited installer will be able to advise on the costs of the various types of panel available.
Where in the District?
Photovoltaic systems can be used successfully in all areas of the South Derbyshire District.
Contact Details
South Derbyshire District Council
Energy Officer
Civic Offices
Civic Way
Swadlincote
DE11 0AH
Tel: 01283 228719
email: energy@south-derbys.gov.uk
page ref SDDC 132