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.
- Will my roof be strong enough to take a solar PV system?
- Check this with your installation company as he should be able to confirm when the survey is completed prior to installation (they must do this before starting any installation). The majority is roofs are strong enough to take the weight of solar panels but should you need any extra reinforcement, you should factor this extra into your calculations and payback.
- Do I need to inform my electricity supplier when I get solar PV panels installed?
- For systems below 4kW peak power your installer will inform them once the installation is complete. In the unlikely event that your system is larger than 4kW you will require permission in advance from your network operator.
- What is a kWh?
- A kWh is a was to measure electricity, particularly electricity that is generated by your renewable energy system. A kWh or 'kilo watt hour' is often referred to as a unit of electricity that is shown on your electricity bill. If an electrical product has a rating of 1 kW it means that it will consume 1 kWh every hour that it is on.
- Will solar PV give me electricity during mains power cuts?
- For the safety of electrical workmen, standard solar PV systems are shut off during power cuts. You can request a system that automatically disconnects your home from the grid during a power cut and provides power from the panels and a battery back up in your home during power cuts.
- Is efficiency important when choosing solar panels?
- Often not, the efficiency of any given panel relates to how effectively it can convert the sun's light. Given that the sun's light is free a panel can simply be made larger to offset a lower efficiency. Only when suitable roof area is at a premium does it make sense to choose high efficiency panels, this will maximise the amount of power that can be generated from the limited space.
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