How do solar panels make electricity?

Electricity from light

A solar panel has no engine, no spinning parts and no fuel. It turns sunlight straight into electricity. This works because of the photovoltaic effect. When sunlight hits certain materials, it knocks tiny particles called electrons loose. A flow of moving electrons is an electric current. 'Photovoltaic' is often shortened to 'PV', so a solar panel is also called a PV panel.

The effect was first noticed in 1839, by a French physicist named Edmond Becquerel. The first solar cells, made in the 1880s, turned less than 1 per cent of the sunlight that hit them into electricity, so they were not much use. Then, on 25 April 1954, scientists at Bell Laboratories in the United States showed off the first practical silicon solar cell. It turned about 6 per cent of the sunlight into electricity, and they used it to run a toy Ferris wheel and a small radio transmitter. Solar cells went on to power satellites in space and, in the end, millions of roofs.

Inside a solar cell

Look closely at a solar panel and you will see rows of dark squares behind a sheet of glass, held in an aluminium frame. Each square is a solar cell. A single cell makes only a small amount of electricity, so a panel joins many cells together.

Most solar cells are made of silicon. Silicon is the second most common element in Earth's crust, after oxygen. It is found joined to oxygen in sand, quartz and many kinds of rock. To make a solar cell, factories heat sand with carbon in an electric furnace to get silicon. They then purify it until it is extremely clean and slice it into very thin wafers. Silicon is a semiconductor, which means it is not a good conductor like copper wire or a good insulator like plastic, but it can be made to behave in a useful way.

A typical cell has two layers of silicon. The thin top layer has a tiny amount of phosphorus added to it. The thicker layer underneath has a tiny amount of boron added. Where the layers meet, an electric field forms. Sunlight is made of tiny packets of energy called photons. When a photon hits the silicon, it can knock an electron free. The electric field pushes the freed electrons one way, and metal on the top and the back of the cell collects them. Connect a wire from the front to the back, and the electrons flow around the circuit. That flow is the electricity.

From the roof to the power point

The electricity from a panel is direct current, or DC, which flows in one direction. The wires in your home, and the grid, use alternating current, or AC, which keeps switching direction back and forth. So a basic rooftop system has two main parts: the panels and an inverter, which changes the DC from the panels into AC that your home can use. Most homes have one inverter, usually near the switchboard. Some have a small inverter on the back of every panel.

The house uses the solar power first. If the panels make more than the house needs, the extra goes out into the electricity grid, and the household may get a small payment for it. At night, or when it is very cloudy, the house takes power from the grid, or from a battery if it has one. A panel makes more power in bright sunlight and less in dim light. Panels also lose some efficiency when they get very hot.

Getting the most from the sun

Efficiency is the share of the sunlight that a panel turns into electricity. The best panels for homes today are about 24 per cent efficient, which is four times better than that first cell in 1954. Most panels come with a guarantee that after 25 years they will still make at least 80 to 90 per cent of their original power.

In most of Australia the Sun is in the northern part of the sky at midday, so panels on north-facing roofs usually make the most electricity over a year. Panels facing east or west make less in total, but they make more in the morning or in the afternoon, when a home may use more power. Australia is a good place for solar. It gets more sunlight on every square metre of land than any other continent. Australian scientists have helped to make solar cells better, too. Professor Martin Green and his team at the University of New South Wales in Sydney developed a cell design called PERC. In 2021, about 9 out of every 10 silicon solar panels made in the world used PERC cells, and in 2022 Professor Green won the Millennium Technology Prize for his work.

Australia's rooftop solar boom

Australia is a world leader in rooftop solar. Depending on how they are counted, between one in three and four in ten Australian homes now have solar panels. At the end of June 2026, the Australian Energy Market Operator (AEMO) counted 3.9 million rooftop solar systems on the National Electricity Market, the main grid that links Queensland, New South Wales, the ACT, Victoria, South Australia and Tasmania. Together they could produce 26.4 gigawatts of power. A watt is a unit of power. A kilowatt is 1,000 watts, a megawatt is a million watts and a gigawatt is a billion watts.

Output depends on the season. Between October and December 2025, rooftop solar on that grid averaged 4,407 megawatts, the highest for any three months up to mid-2026. On Wednesday 3 December 2025, in the half-hour ending 12.30 pm, rooftop solar set a record peak of 16,319 megawatts. In April to June 2026, when the Sun is low and the days are short, rooftop solar still supplied about 10 per cent of the electricity on the grid. It produced more power than ever before for those three months of the year.

The boom is still going. The Clean Energy Regulator says that a record 1 gigawatt of rooftop solar was installed in Australia in April to June 2026, and that the average new system was about 10.5 kilowatts. In April 2026, when many households rushed to install before the battery rebate changed on 1 May, more than 8 out of 10 new solar systems were installed with a home battery, to store the sunshine for the evening.

📚 Words to know

Photovoltaic effect

When light hits certain materials and knocks electrons loose, so that an electric current can flow.

Semiconductor

A material, such as silicon, that is neither a good conductor nor a good insulator of electricity. Solar cells are made from semiconductors.

Photon

A tiny packet of light energy. When photons hit a solar cell, they can knock electrons loose.

Inverter

A device that changes the direct current (DC) from solar panels into the alternating current (AC) used in homes and on the grid.

Efficiency

The share of the energy that goes into a machine that comes out as useful energy. A panel that is 24 per cent efficient turns 24 per cent of the sunlight it gets into electricity.

🧪 Try this: test a solar-powered gadget

1. Find something solar-powered, such as a solar calculator, a garden light or a toy solar car or fan from a kit. Look for the dark panel. Those are the solar cells. Do not use any real roof panels or inverters. They carry electricity that can be dangerous, so never touch them or go up on a roof.
2. Test it in bright sunlight and see how it works. Then use your hand to shade half of the panel. Then shade all of it with a sheet of paper, then with a few layers of paper. What happens each time? With a solar car, time how long it takes to cross a one-metre track.
3. Now test the angle. Hold the panel flat on the ground, then tilt it towards the Sun, then tilt it away. When does it work best? Safety: never look straight at the Sun, and do not use a magnifying glass on the panel.
4. Make a table with the columns 'light' and 'result'. Test full sun, shade, a cloudy day and an indoor lamp, and write down what you see or the time it takes.
5. Challenge: in Australia, why do house roofs usually carry panels that face north? Try to explain it using your angle tests and where the Sun is in the sky at midday.