Log in to personalise your experience and connect with IOP.

Solar panels

First used to generate power for early spacecraft, solar panels are now found all over the world, powering communities without generating carbon emissions. How do solar panels convert sunlight into electricity? What do you need to keep in mind when designing a solar farm to make it as efficient as possible?

Up on the roof of the Institute of Physics building is a small ‘solar farm’ of solar panels. They cover about half of the roof where they are in full sunlight in order to generate electricity which contributes to the electricity used in the building.

There are 54 panels with a total area of 88 m2. They are aligned to be roughly south-facing and tilted to maximise the amount of sunlight they collect.

The higher the efficiency of your panels, the greater the cost savings.

How does a solar panel work?

Solar panels – also known as photovoltaic (PV) panels – are made from silicon, a semiconductor material. Such a material has some electrons which are only weakly bound to their atoms. When light falls on the surface of the silicon, electrons break free and can become part of an electric current.

How much power do solar panels provide?

The solar panels at IOP produce twice the electricity in summer than in winter.

Solar panels have become much cheaper in recent years. They have also become much more efficient – they produce more electrical power from the sunlight falling on them. The panels on the roof of the Institute of Physics building are among the most efficient in the world, producing over 200 watts per square metre (W/m2).

Of course, solar panels work best in strong sunlight. They produce most electrical power when the Sun is at its highest – in the middle of a summer’s day – and less early and late in the day and during the winter.


  • Solar panels generate electricity without producing carbon dioxide emissions (though there are likely to be carbon emissions during their manufacture).
  • A PV system has no moving parts to go wrong.
  • PV panels can last for 20 years or more with very little maintenance so that, once the initial cost has been paid, the electricity they produce is almost free.