How do solar PV panels work?
A solar PV system captures the sun’s energy and uses it to generate electricity. The system will continue to work even in cloudy conditions. Not only could you save money by generating your own electricity, you could also earn money from the Government's Feed-In Tariff.
Technical information made simple
Solar PV panels are made up of solar cells. Each cell is made from one or two layers of semi-conducting material, typically silicon, covered by non-reflective glass. Here’s how a typical system works:
- The light shines on the cell and this creates an electric field across the layers, causing electricity to flow.
- The electricity flows through a cable and is collected at a central point generally under the panels and located in your roof space.
- The electricity produced is Direct Current (DC) and needs to be converted to Alternate Current (AC) by an inverter which is fitted as part of the system. This is AC current is then used in your home to power your lights and appliances.
- If you don’t use all the electricity that you have generated, it will be fed into the National Grid automatically. It is estimated that you will export 50-75% of the electricity you generate. If the system can’t provide you with enough electricity, i.e. at night, the Grid will automatically supply you as it does now, for which you will be charged.
The stronger the sunshine, the more electricity you can produce, but PV cells don’t need direct sunlight to work – you can still generate some electricity on a cloudy day.
The strength of a PV cell is measured in kilowatt peak (kWp). That’s the amount of energy the cell generates in full sunlight. This rating will determine the amount of electricity that you can produce. Typical domestic units are 3 or 4 kWp.
- What is a Renewable Obligation Certificate (ROC)?
- The government created an obligation for electricity suppliers to encourage homeowners to fit specific renewable micro generation systems. For domestic electricity generation, this system has now been superseded with the Feed in Tariff (FIT).
- What is the difference between monocrystalline and polycrystalline PV panels?
- Firstly, they look different - polycrystalline wafer has a dark blue colour, whereas monocrystalline wafer is black. Monocrystalline panels tend to be slightly more expensive and efficient than polycrystalline panels,
- Is there an approvals standard for solar PV panels?
- Yes, solar panels can be approved by the Microgeneration Certification Scheme (MCS). In order to qualify for the Feed-In Tariff scheme you must ensure that you use MCS approved panels.
- How are solar PV panels fixed to the roof?
- This will depend on the roof, but typically solar PV panels are fixed using rigid stainless steel brackets that are fixed directly to your roof rafters. The brackets hook out from underneath your existing tiles. Tiles or slates should not be drilled to fit the panels, nor should mastic/silicone be used to weatherproof your roof. Solar panels can be fitted to any roof type except thatched roofs.
- Are solar PV panels fragile?
- Solar PV panels are very robust; they are designed to withstand the normal stresses and strains subjected to them by nature. You can ensure that your panels are robust by purchasing only MCS accredited panels.
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