Solar panels on the roof of a house

How does solar power work?

Have you ever wondered how solar panels turn sunlight into electricity? And how does shade affect a solar photovoltaic (PV) system, like on a cloudy day?

How sunlight is converted to electricity

When sunlight hits the PV cells in a solar panel, electrons are knocked loose and move around. These loose electrons can be captured so they move in the same direction around a circuit. An electric current is formed by this flow of electrons in the same direction.

By connecting many PV cells to each other in a panel and wiring a number of panels together (called an array), a flow of electrons is created and produces direct current (DC) electricity. The more panels in an array, the more electricity is made.

In our homes and businesses we use 240 volt alternating current (AC) electricity. Therefore, a box called an inverter - usually no bigger than your average shopping basket - is used to convert the DC electricity to AC so it can be used in your premises.

What happens on a cloudy day?

Even a cloudy day is sufficient to generate some solar power, although a lot less than a sunny day.

It's important to remember that in a solar panel array, shade blocks the flow of electricity through the panels. Even if shading is on just one of the panels, the output of the entire array will be reduced.

More advanced panels and inverters can lower the impact from shade, so ensure you discuss this with your solar retailer.

While you don’t have any control over shade from clouds, you should position your panels in an area free of shadows from other things, such as trees and buildings.

If this is not possible, you may have the option of splitting your solar panels across parts of your roof which face different directions. For this kind of set-up, you will need an inverter that can accept multiple inputs for the best results. Your solar installer can advise on this.

Also, many modern solar panels come equipped with devices called bypass diodes. These devices reduce the effects of partial shading by enabling electricity to ‘flow around’ the shaded area.

There are even panels that are designed to operate effectively in part shade. Ask your solar retailer more about this technology.