How to buy solar panels How solar photovoltaics work
Solar photovoltaics explained
Solar panels being installed on a roof
Solar panels
Solar photovoltaic (PV) systems convert energy from the sun into electricity. Solar PV systems can be relatively simple, with their main components being solar panels or modules.
Solar panels are made of a thin layer of semi-conducting material between a sheet of glass and a polymer resin.When exposed to daylight the semi-conducting material becomes 'energised' and this produces electricity.
Each solar PV panel typically has an area of around 1.2 to 1.8 square metres, depending on the manufacturer, and will produce about 180-250 Watts. So to produce 1kW of power, you would need four or five solar panels.
Basic elements of a domestic solar photovoltaic system
The more panels you can fit on your roof, the more expensive the system will be to install, but the more electricity you will produce.
Panels are pretty much maintenance-free and should last for at least 25 years. If your roof has a fairly shallow pitch or is flat, it may accumulate bird droppings, leaves or dirt, so the solar panels will need occasional cleaning.
The rest of the PV system
The electricity produced by the PV panels is direct current (DC). Before it can be used in the home it has to be converted to safer alternating current (AC), using a box called an inverter, often placed in the loft. It is worth noting that the inverter doesn't have the same lifespan as the panels themselves, and if it fails, then a replacement inverter could cost at least £1,000.
For safety, isolator switches are also placed before and after the inverter.
3.5kW PV system about to be installed. Scaffolding is up (courtesy of Chris Wheatley)
A PV generation meter is connected inside your home, in a visible location, so you can see a real-time display of how much electricity the system is generating. The meter also measures the amount of electricity exported to the grid, and provides the basis on which you will get your feed-in tariff payment.
Finally, if you want to export excess electricity to the grid, there will be another cable to your consumer unit (fuse box).
Look at the FAQs section in our How to buy solar PV guide for further information and advice.
The installation process
3.5kW PV system after installation (courtesy of Chris Wheatley)
If the panels are to be installed on your roof, it is likely that the installers will need to erect scaffolding for the installation. Make sure you check with the surveyor that there is space to install scaffolding and that the quote includes the cost of the scaffolding.
Once the scaffolding is up, the panels could be installed in less than a day. Roofers will attach the fixing brackets onto the rafters of your roof (hence why a proper surveyor should go into your loft to check the integrity of the roof and the rafters). The solar panels will then be clamped onto the fixing brackets.
The pictures on this page show a Which? member's roof before and after the installation of a 3.5 kW PV system.
Replay our solar panels live Q&A
Our team of experts were inundated with questions from homeowners considering their solar options during our live Q&A, covering everything from energy savings and feed-in tariffs to installation, inverters and maintenance.
Missed it? You can rewind and replay all the action at Which.co.uk/solarlive.
- Which? advice: is solar PV a good investment?
- Earn money from solar PV with the feed-in tariff (FIT)
- Renovating your home? Read our guide to planning permission and building regulations
