Solar PV FAQs
Your guide to understanding Solar Photovoltaic (Solar PV)
How does Solar PV work?
A typical domestic system is between 1.5 to 3kWp. Each kWp should generate around 800 to 850kWh per year if unshaded and perfectly south facing with a tilt of around 30–50°. A solar roof array would typically generate 1200 to 2400kWh per year depending on size.
What do kWp and kWh mean?
Solar electricity systems are sized in kilowatts peak (kWp). This is essentially the rate at which it generates energy at standard test conditions (Irradiance 1000 W/m², Cell Temperature 25°C, Air Mass AM1.5). The kWp of a PV system will vary depending on the number and power of the individual modules used which in turn depends on how much a customer budget and the roof area available to accommodate the panels.
What size do Solar PV Systems come in?
PV systems are modular, allowing a great degree of flexibility in design and specification. In practice, the size of a system is determined by the power and number of modules fitted to the available roof space.
Why is shade a problem for Solar PV systems?
Any shading has a detrimental effect on the electricity your system generates. Shading may come from trees, chimneys or surrounding buildings. Shading is a very important factor in the solar PV output. However, if your panels are partially shaded in the early morning or late evening, the system will still generate acceptable yields. Installers assess and highlight any shading concerns and give a realistic electricity generation potential
Can I still install a Solar PV system on an old and deteriorating roof?
Although Solar PV systems are not normally heavy enough to cause structural problems, if your roof is in poor condition your installer would recommend that a structural survey be completed before proceeding with your installation.
What is the life expectancy of a Solar PV system?
Under normal conditions you can expect modules to operate for 25 years or more before they need replacing, although the inverter may need replacing earlier than this.
How long will my solar installation take?
A typical domestic solar installation will take place over two days but this may vary due to many factors . Depending on the building we access to erect and remove scaffolding will also be required. Your installer can advise the specific details for your property in his quotation.
How do I find an installer?
The installer must be certified under the Microgeneration Certification Scheme (MCS). You can find certified installers at www.microgenerationcertification.org. Rexel's service offering, Solar Energeasy has trustworthy MCS accredited installers signed up who have been fully vetted that will give you peace of mind.
How does the Feed in Tariff System operate?
There are three ways in which the owner of the technology can benefit from the scheme. These are: