Solar PV (Solar photovoltaics)
Solar PV (photovoltaic) uses energy from the sun to create electricity to run appliances and lighting. PV requires only daylight - not direct sunlight - to generate electricity.
How it works
Photovoltaic
systems use
cells to convert solar radiation into electricity. The PV cell consists
of one or two layers of a semi conducting material, usually silicon.
When light shines on the cell it creates an electric field across the
layers, causing electricity to flow.
The greater the intensity of the light, the greater the flow of
electricity...
PV systems generate no greenhouse gases, saving approximately 455kg of
carbon dioxide emissions per year - adding up to about 11
tonnes over a
system's lifetime - for each kilowatt peak (kWp - PV cells are referred
to in terms of the amount of energy they generate in full sun light).
PV arrays now come in a variety of shapes and colours, ranging from
grey 'solar tiles' that look like roof tiles, to panels and transparent
cells that you can use on conservatories and glass to provide shading
as well as generating electricity. As well as enabling you to generate
free electricity they can provide an interesting alternative to
conventional roof tiles!
Solar PV
and your home
You can use PV systems for a building with a
roof or wall that
faces within 90 degrees of south, as long as no other buildings or
large trees overshadow it. If the roof surface is in shadow for parts
of the day, the output of the system decreases.
Solar panels are not light and the roof must be strong enough to take
their weight, especially if the panel is placed on top of existing
tiles.
Solar PV installations should always be carried out by a trained and
experienced installer.
Cost and
maintenance
Prices for PV systems vary, depending on the
size of the
system to be installed, type of PV cell used and the nature of the
actual building on which the PV is mounted. The size of the system is
dictated by the amount of electricity required.
For the average domestic system, costs can be around £5,000- £8,000 per
kWp installed, with most domestic systems usually between 1.5
and 3
kWp. Solar tiles cost more than conventional panels, and panels that
are integrated into a roof are more expensive than those that sit on
top.
If you intend to have major roof repairs carried out it may be worth
exploring PV tiles as they can offset the cost of roof tiles.
Grid connected systems require very little maintenance, generally
limited to ensuring that the panels are kept relatively clean and that
shade from trees has not become a problem. The wiring and components of
the system should however be checked regularly by a qualified
technician.
Stand-alone systems, i.e. those not connected to the grid, need
maintenance on other system components, such as batteries.
Planning
considerations
Some local authorities require planning
permission to allow
you to fit a PV system, especially in conservation areas or on listed
buildings. Always check with your local authority about planning issues
before you have a system installed. Obtaining retrospective planning
permission can be difficult and costly.
