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Photovoltaics
(PV) is the conversion of light into electricity.
Photovoltaic
Modules
 PV modules consist of a number of semiconductor
PV cells connected together to provide a 'standard' voltage of 12V DC. Current and hence
power output varies with light level up to peak output in full bright sun. Although the
output could be used to directly power DC appliances, such as pumps, due to the
variability of sunlight PV modules are usually connected to charge batteries for DC stand
alone systems or connected to the mains grid through an inverter for AC grid connected
systems.
These maintenance free panels have
no moving parts, make no noise, cause no pollution, and will produce useful power even
under a grey overcast sky.
A solar electric system has the
advantage of being quick and easy to install with a minimal requirement for site
preparation. Also their modular design allows the easy expansion of a smaller system if
needs change.
Simple and reliable, they are ideal
for:
 Stand Alone Applications:
- Rural and remote power needs
- Maintaining the charge in
infrequently used batteries
- Powering lighting, pumps &
garden fountains
- Charging batteries on boats and
caravans
- Providing reliable electricity
supplies for properties off the grid
 Grid Connected Applications:
- Domestic grid connected systems
-
Megawatt utility powerwatt generation
-
Integrated into building facades
-
Mounted on domestic roofs
-
Used as the roofing material itself
Photovoltaic systems are the only
form of renewable energy that can be widely deployed in towns and cities. Where appropriate
‘hybrid’ systems combining PV with wind turbines or other forms of power
generation can give a balanced supply all the year round. (see page on
system sizing)
Over
it's estimated life, a PV module in a sunny climate can produce at least
20 times the electricity used in it's production.
Choosing PV Modules
Photovoltaic
modules vary and a wide range are available for every application. They
must be chosen carefully, the following factors are important in making
that choice:
Warranty
Normally
stated as a guarantee to produce no less than a percentage of power
rating for a given period.
Only of any
value if the manufacturer of the module is likely to still be in
business for that time period.
Quality
How well the
modules are made. This affects how well they will work and will last.
Illustrated by features such as strength of frame and efficiency.
Power
Tolerance
Normally
stated as a plus and minus percentage of power rating.
This is
important when comparing prices - eg. a 170 Wp module with +/- 10% power
tolerance may only produce 153 Wp so may not be such good value as a
more expensive module with a tighter power tolerance.
BP Solar
Saturn modules have a +2.5%/-0% tolerance this means they will produce
at least their rated power.
Multicrystalline modules have a +/- 3% tolerance unless otherwise
stated.
Energy
Production
Normally
stated in terms of kWh/kWp per annum ie. Energy that should be expected
per year from a well sited 1kWp PV system. This depends upon efficiency
of the module, accuracy of it’s power rating and responsiveness to
varying light levels. Different modules with the same nameplate rating
will produce differing amounts of energy and will age differently.
All the
modules in this catalogue have been chosen to be amongst the best
available considering the above criteria.
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