The Renewable Energy Company
SOLAR PV SYSTEMS
Solar PV
HOW DO SOLAR PV PANELS WORK?
A solar PV panel consists of many cells made from layers of semi-conducting material, most commonly silicon. When light shines on this material, a flow of electricity is created.
The cells don’t need direct sunlight to work and can even work on cloudy days. However, the stronger the sunshine, the more electricity generated.
Solar PV systems are made up of several panels, with each panel generating around 355W of energy in strong sunlight. Typical systems contain around 15 panels and generate direct current (DC) electricity. Because the electricity used for household appliances is alternating current (AC), an inverter is installed along with the system to convert DC electricity to AC. This electricity can be used throughout your home, or exported to the grid.
Are Solar Panels Right For Me?
DO YOU HAVE ENOUGH SPACE?
Space is a key consideration. The average system size is around 4.2kWp and this will typically take up around 25m2 roof area. An unshaded, South facing roof is ideal for maximum electrical output. East or West facing roofs could still be considered, but North facing roofs are not recommended. A system facing East or West will yield around 15-20% less energy than one facing directly South.
SHADED ROOFS
Any nearby buildings, trees or chimneys could shade your roof and have a negative impact on the performance of your system.
Finding an unshaded spot is best, however sometimes shading is unavoidable. Some solar PV systems can minimise the impact of shading using ‘optimisers’. If you don’t have shading, the use of optimisers is not necessary or beneficial, other than the increased monitoring opportunities they offer – they won’t generate more energy.
Do I need permission to install a solar PV system?
Solar PV panels are considered ‘permitted developments’ and often don’t require planning permission. However, exceptions apply and it’s best to check with your local planning office for guidance. If you live in a listed building, conservation area or national park, additional restrictions may apply.
If you’re planning to install a solar PV system in your home, you must register it with your Distribution Network Operator (DNO). The DNO is the company responsible for bringing electricity to your home. Usually, your installer will register the device for you.
Getting the most out of your solar PV system
Reduce your elctricty use
During daylight hours, you’ll be generating electricity even on cloudy days, but if you’re using more power around your home than your panels are generating, or during the evening when your panels are not generating any electricity, you’ll be
supplementing this by importing electricity from the grid.
Reducing your electricity use can help lower your bills and
reduce your carbon footprint. If you’re claiming a Smart
Export Guarantee tariff, you’ll receive a payment for every unit of electricity you export. Remember to turn devices off and avoid standby.
Use more electricty during the day
As your solar PV system will be working at its peak during
daylight hours, it’s a good idea to run your electrical appliances such as your washing machine, dishwasher, and iron during the day. If you’re at home, then this may be easier to do, but if you are away during the day, you could try setting timers for your dishwasher and washing machine.
Combine with other renewable systems
You can combine solar PV with other renewable technologies such as heat pumps or solar hot water systems. These
technologies work well with each other, as solar PV could help power a heat pump, for example, or several of these systems could feed into a thermal store.
MAINTENANCE
Solar PV systems need little maintenance. Keep an eye on nearby trees to ensure they don’t begin to overshadow your system.
In the UK, panels that are tilted at 15 degrees or more benefit from being cleaned by rainfall, which helps to ensure optimal performance. Debris is more likely to build up if you have ground-mounted panels,
or if you live in an area with more dust in the air. In these cases, you might need to have the panels cleaned occasionally.
Once fitted, your installer should leave written details of any maintenance checks that you should carry out to ensure everything is working properly. This should include details of the main inverter fault signals and key troubleshooting guidance. Ideally, your installer should demonstrate this to you once the system has been installed.
Keeping a close eye on your system and the amount of electricity it’s generating (alongside the weather conditions) will help you understand what to expect and alert you to when something might be wrong.
The panels should last 25 years or more, but the inverter is likely to need replacing sometime during this period, at a cost of around £800 (depending on system size and the manufacturer). Some inverters have online monitoring functions and can warn you by email if the system fails.
Most inverters have warranties of five years as a minimum, which can often be extended up to 15 years. Speak to your installer about the likely lifespan and benefit of an extended warranty. You might find that a 15-year warranty costs almost as much as a replacement inverter, so consider it carefully.
Consult with your installer for exact maintenance requirements before you commit to installing a solar PV system.