Solar panels, as we know them have been around since the 1950s, when the first silicon photovoltaic cell was developed in the US. They are now a common sight on the rooves of houses, some transport vehicles, calculators, and speed cameras. There is even a government-backed scheme offering large cash incentives to convert your home to solar power. But how to they work?

Solar panels are made up of ‘photovoltaic’ cells. 

Photo = Light. Voltaic = Electricity.

 The photovoltaic cells, also referred to as PV cells, are made of layers of silicon. The top layer of silicon has been engineered so that its atoms have too many electrons. The bottom layer is engineered so that its atoms do not have enough electrons. This sets the scene for an electronic current to develop later on. All that is now needed is a trigger – in this case, sunlight.

Light has its own energy. When sunlight hits the PV cells, which are encased in non-reflective glass to maximize efficiency, it shakes loose some of the ‘spare’ electrons from the first layer of silicon. Silicon is a conductor, meaning that electricity can pass through it, and so the freed electrons begin to move towards the bottom layer.

Electrons that are moving in the same direction constitute an electronic current. When the electrons reach the bottom layer they are channeled by the metal contacts that are situated at each end of the PV cell, allowing the electricity to be drawn off and used. During this part of the process the electronic current is converted from a direct current (DC) to an alternating current (AC). This process is called inversion and it means that the electricity can be used to run appliances and power the home. 

Solar panels don’t need direct sunlight to work – they can still generate electricity in dull weather. However, due to how the process works, more energy is generated in strong sunlight – hence why the most common place for solar panels is on the roof.

The electricity from solar panels is measure in kilowatts-peak (kWp), which refers to the rate at which electricity is generated at peak performance.