How do solar panels work?

The 30-second take

• Solar panels generate DC electricity directly from light, not from heat. They work fine on cool days and lose output on cloudy ones.
• An inverter converts DC into the 230V AC your appliances use. It’s the hardest-working component and usually the first to need replacing.
• Your home automatically uses solar power first, then draws the shortfall from the grid.
• Surplus power is exported to the grid for a feed-in tariff, or stored in a battery if you have one.
• Panels have no moving parts and typically carry 25-year performance warranties; the electrical work around them is where quality shows up.

Step 1 — the panel turns light into electricity

A solar panel is a sheet of silicon cells under glass. When light hits a cell, it knocks electrons loose, and the cell’s construction pushes those electrons in one direction. That directional flow is direct current, or DC, electricity. This is called the photovoltaic effect, and it is why solar panels are also called PV panels.

Two things follow from that. Panels respond to light, not heat, so a bright cold day is excellent generating weather and a very hot day actually reduces efficiency slightly. And output tracks available light through the day, ramping up in the morning, peaking around the middle of the day, and dropping off in the afternoon.

Step 2 — the inverter makes it usable

Your house runs on 230V alternating current. Panels produce direct current. The inverter sits between them and converts one into the other, thousands of times a second, every daylight hour for the life of the system.

There are three common architectures, and the difference matters mostly for shade and monitoring:

• String inverter. One inverter for the whole array, with panels wired together in a series. Simple and cost-effective, but heavy shade on one panel drags on the string.
• Microinverters. A small inverter under each panel, so each one operates independently. Better on complex or shaded roofs, and gives panel-level monitoring.
• Optimisers with a string inverter. A middle path — a small device on each panel manages its output, feeding one central inverter.

Because the inverter is the component doing continuous work, it is typically the first thing to need replacing, often around the 10 to 15 year mark, while the panels are still under performance warranty. That is why inverter quality deserves more attention than it usually gets.

Step 3 — your house uses it first

Solar electricity does not go to the grid and come back. It flows to your switchboard and your appliances take it first, automatically, with no action from you. If your system is generating 3 kW and the house is drawing 2 kW, the house runs entirely on solar and 1 kW is surplus. If the house is drawing 5 kW, solar supplies 3 kW and the grid quietly makes up the other 2 kW.

This is the reason self-consumption matters so much to the economics. Electricity you use as it is generated is worth your full retail rate, because it is electricity you never buy.

“Nothing switches over and nothing needs your attention. Your appliances simply take solar first and the grid fills the gap.”

Step 4 — the surplus goes somewhere

Whatever your house doesn’t use has two possible destinations. Without a battery, it is exported to the grid and your retailer credits you a feed-in tariff — typically a small fraction of what you pay for the same electricity. With a battery, the surplus charges the battery first, and you draw on it in the evening instead of buying power at the full rate.

Your meter records both directions, which is why a solar bill shows electricity imported and electricity exported as separate lines.

Inside the cell: how sunlight becomes electricity

Step 1 above is the whole trick, so it is worth one level deeper. A solar panel is a sheet of photovoltaic cells, and a PV cell is two thin layers of silicon treated so that one layer has a slight surplus of electrons and the other a slight shortage. Where they meet, that imbalance creates a permanent electric field.

Sunlight arrives as photons. When a photon of the right energy strikes the silicon, it knocks an electron loose. On its own that electron would drift and settle — but the built-in field pushes it in one direction, and a grid of fine metal contacts on the panel collects the flow. Electrons moving in one direction is a direct current. That is it: no combustion, no moving parts, nothing to wear out mechanically.

Which explains two things people find counter-intuitive. Panels work on light, not heat — a cold clear day is excellent and a hot still day is slightly worse, because silicon gets less efficient as it warms. And a panel with no moving parts is why the panels are almost never the component that fails.

How much power does one solar panel actually produce?

A modern residential panel is typically rated between about 400 and 500 watts. That rating is measured under standard test conditions in a laboratory, which your roof is not, so treat it as a comparison figure between panels rather than a promise of output.

What you actually get depends on four things: how much sun your location receives, which way the panel faces and at what pitch, the temperature, and whether anything shades it. The same panel in Darwin and in Hobart will not produce the same amount in a year, and the same panel on a north-facing roof and a south-facing one will not either.

The practical way to think about it is at system level rather than panel level. Your installer should be modelling annual output for your actual roof, in your actual postcode, at your actual orientation — and if a quote gives you a single national number instead, that is the thing to question.

• Rated watts are a lab figure. Useful for comparing panels, not for predicting your bill.
• Orientation and pitch move output more than brand does on most Australian roofs.
• Heat reduces efficiency. Panel output on a 40°C day is lower than on a mild sunny one, which surprises almost everyone.
• Shade is the big one. A single shaded panel can drag a whole string down unless the system is designed for it.

So what does solar actually get you?

The mechanism above turns into four benefits, and they are worth separating because they are not equally large.

• A lower bill, mostly from self-consumption. Every kilowatt-hour you use as your panels produce it is one you do not buy at the retail rate. This is by far the biggest number.
• A small export credit. What you do not use is exported for a feed-in tariff, which is real but modest and has been falling.
• Insulation from price rises. The share of your consumption you generate yourself is a share that stops tracking the retail market.
• Lower emissions, immediately and for the life of the system.

What solar does not automatically get you is backup power. A standard grid-connected system shuts down in a blackout for safety reasons, whatever the sun is doing — a genuine surprise to many owners, and a separate decision involving a battery.

What this means when you’re buying

Understanding the chain changes what you look at in a quote.

• The inverter is not a detail. It works hardest, fails first, and determines how the system copes with shade.
• Shade is an architecture question. If part of your roof is shaded for part of the day, that should change the design — not be quietly ignored.
• Panel efficiency matters most when roof space is tight. With plenty of roof, a slightly less efficient panel is rarely the problem worth solving.
• Nearly everything else is electrical work. Cabling, isolators, switchboard connections, mounting and compliance — all invisible from the ground, and all things a discount quote can cut.

The Clean Energy Regulator inspected 1,278 home battery installations between July 2025 and April 2026 and classified more than 60% as substandard. The technology itself is mature and reliable. The variable is who bolts it to your roof and wires it into your switchboard.

Read next

• Is solar worth it in Australia?
• How solar batteries work
• What size solar system do you actually need?
• How to choose a good solar installer
• Solar panels — how they fit your home

Sources

• cleanenergycouncil.org.au — consumer guide to solar PV
• uts.edu.au — CER battery inspection findings, April 2026