How do solar panels work?

Let the sunshine in! Tracing the path of energy originating 150 million kilometres away to the on-switch of your appliances.

We all understand the basic idea behind solar power: the sun’s energy can be used to generate electricity. But how exactly do solar panels work? Here, two experts explain some key principles behind solar panels and correct a common misconception.

Solar PV and solar thermal

The dominant form of solar energy production is known as “solar PV” which uses photovoltaic panels that absorb sunlight and convert it to electricity. You may also come across solar thermal technology, more commonly referred to as solar hot water. 

How do solar panels produce power?

Solar panels generate electricity when the sun shines on them. “Photons, which are ‘particles of light’, knock electrons free from atoms within solar cells which generates a flow of electricity, otherwise known as an electric field,” explains Dr Sven Teske, a research director at the Institute for Sustainable Futures at the University of Technology, Sydney.

What are solar panels made of?

Solar panels consist of numerous small photovoltaic cells made of a semi-conductive material, usually silicon. The panels have three main layers: the front glass; the silicon cells, which are connected via a conductive material such as silver; and the back glass or plastic.

What is an inverter?

“Solar photovoltaic cells produce variable direct current – or DC – output,” Teske says. “But the electric systems in all ‘poles and wires’ as well as in households and offices use alternating current, or AC.”

An inverter is a box that sits near your solar panels and converts DC output to AC output so it can be used by the machines and appliances in your home.

Do solar panels need heat to work?

No – solar panels need sunlight, not heat, to operate. In fact, cool weather with clear skies is the best environment for solar PV.

“The panels actually start to lose efficiency when it gets hot – above 30 degrees or so,” says Nik Midlam, Manager of Carbon Strategy at the City of Sydney. “But the conditions in coastal Sydney are significantly milder than they are in Western Sydney, for example. That makes the City of Sydney well suited to solar.”

What happens to the electricity I generate if I don’t use it?

If your panels are generating excess electricity at certain times of day, you may be able to sell it. “Many of us don’t use a lot of energy at home during the middle of the day but, with solar power, any energy you don’t use can be sent back to the grid and used by other consumers nearby,” Midlam says. “Most energy retailers will pay you for that excess energy.”

Solar battery storage

Another option is battery storage. Adding a battery to your solar PV system allows you to store excess electricity created during sunny periods so it can be used at night or when there is less sunshine.

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