Solar PV systems use photovoltaic panels to generate electrical power from sunlight using a thin layer of semi-conducting material. Known as a solar cells, these are typically made from silicon and encased within a sheet of glass and polymer resin to a solar panel. A solar array consists of a number of solar panels connected in series and parallel configurations and mounted on a roof-top or other outside structure. In order to perform efficiently, tje solar array must be installed in the best possible location and optimised to work under all conditions.
Solar PV systems can produce electricity even on dull days but the more exposed to direct sunshine they are, the better the system will work and the more electrical energy it will produce. For that reason, siting solar panels on a South facing roof, tilted at a pitched angle of 30-50° is the optimum option. Installations facing anywhere to the South or due East and due West are feasible but will not produce as much output. Installation is not recommended on North facing roofs. In the UK, the highest seasonal performance will be in May, June and July when we get the most sunshine.
The amount of electricity generated by a solar PV system can also vary depending upon where you live in the UK. Northern areas tend to receive slightly less sunlight over the course of a year than those in the South, however, solar electricity system are still viable in Northern areas as the differences between North and South in terms of sunlight potential are small. As your installer, we will estimate how much electricity your system will generate in your area for you.
In terms of your solar panel site, the shape of the roof is important too. Solar PV arrays are made up of modules of 1.5 square metres. This allows most available roof shapes to be accommodated. Typical UK installations are 14-15 square metres in size. A 12kWp (kilowatt peak) system could comprise of 12 panels taking up an area of 15 square metres. It could generate around 1800kWh (kilowatt hours) per annum.
In order to maximise the performance of your solar PV system, your solar panel site should be free from shading of any description, particularly during peak daylight hours of 10am – 4pm: foliage, trees, down pipes, adjacent buildings. Even shading of a single module will affect the performance of the whole array as all modules are electrically and physically connected.
In England, Wales, Scotland and Northern Ireland, changes to permitted development rights for domestic renewable technologies mean that most solar electrical installations do not require planning permission provided they respect certain criteria; panels should not protrude more than 200mm when installed, for example. Particular exceptions apply for installations on flat roofs, listed buildings and buildings in conservation areas, world heritage sites and designated landscape areas. These may require approval from building control.
The best solar panel site for your renewable power system should also have good access for installation, maintenance and repair if necessary. If access requires the use of specialist equipment (cranes, lifting gear etc.) it will be too expensive to make the system viable.