How do solar panels work?

How does sunlight actually become electricity?

The important correction to a common mental picture is this: a photon does not replace an electron or a molecule. It transfers energy. Think of the photon as giving an electron a shove, not taking its seat.

What is the difference between a solar cell, a solar panel and a solar system?

When people say “solar panel,” they often mean the visible module on the roof. The actual conversion of light energy begins inside the individual photovoltaic cells within that module.

1. Sunlight arrives as packets of energy

Light behaves in ways that can be described as tiny packets of energy called photons. Different photons carry different amounts of energy.

The panel does not “store sunlight” at this point. It is using the incoming light energy immediately.

2. The photon gives an electron enough energy to move

Most rooftop solar cells use silicon, a semiconductor. Its electrons are normally tied up in the material's atomic bonds. When the cell absorbs a photon with enough energy, that energy can free an electron to move through the material.

When that electron leaves its original position, it also leaves behind an empty place physicists call a hole. You can think of the empty seat appearing to move as neighbouring electrons fill it one after another.

3. The solar cell has a built-in way to separate charges

Freeing electrons is not enough. If they simply wandered around and immediately fell back into their old positions, we would get very little useful electricity.

Solar cells are engineered with differently treated layers of semiconductor material. Where those layers meet, they create an internal electric field that helps separate negative electrons from positive holes.

This built-in field is a crucial part of the photovoltaic effect. It helps create the voltage that can push charge through an external circuit.

4. Metal contacts give the electrons a path around the circuit

The thin conductive lines you can see on many solar cells collect electrical charge. Once the solar cell is connected into a circuit, electrons can travel through the external wiring. That organised movement of charge is electrical current.

The electricity produced by the panels is direct current (DC): the electrical flow has a consistent direction.

5. The inverter translates panel electricity into household electricity

Australian homes use alternating-current (AC) electricity. Solar panels produce DC electricity, so an inverter sits between the panels and the home's AC electrical system.

Once converted to AC, the electricity can be used by the home. Depending on the system, surplus can charge a compatible battery or be exported to the grid. If the home needs more than solar and storage can supply, the balance comes from the grid.

What do solar panels actually do for a house?

They provide electrical energy whenever enough sunlight is available. In a normal grid-connected home, solar generated behind the meter reduces the amount the household needs to draw from the grid at that moment.

The smart meter records the net electricity flowing through the grid connection. Solar used directly inside the home never needs to be imported through that meter.

What does a 6.6 kW or 10 kW solar system actually mean?

The kW rating describes power capacity, not how many kilowatt-hours the system will generate every day. A 6.6 kW array is 6.6 kW of rated panel capacity under standard test conditions. Real output changes through the day with sunlight, temperature, orientation, shading and system losses.

The Australian Government's current consumer guidance gives Melbourne an illustrative annual-average generation figure of about 3.6 kWh per day for each 1 kW of panels. That means a theoretical 6.6 kW array would average about 23.8 kWh/day using that broad benchmark, but individual homes vary materially and generation is higher in summer and lower in winter.

That benchmark is useful for understanding scale, not for quoting a property. Roof direction, tilt, shading, equipment and local conditions need to be modelled for an actual system.

Do solar panels keep working during a blackout?

Ordinary grid-connected rooftop solar usually stops supplying power during a grid outage, even if the sun is shining. A standard grid-interactive inverter needs the grid or an equivalent stable AC supply to operate and must disconnect when the grid goes down.

This anti-islanding behaviour protects people working on the electricity network and prevents an ordinary solar system from energising wiring that is expected to be de-energised.

Keeping selected circuits running during an outage requires a system specifically designed for backup, such as a compatible battery, backup gateway or changeover arrangement. Having solar panels and a battery does not automatically mean every circuit or every phase will remain powered.

See how battery backup works during Victorian blackouts ↗

Do solar panels work on cloudy days or at night?

Cloudy days: yes. Diffuse sunlight still contains photons that can reach the cells, but output is usually lower than under strong direct sunlight. The exact reduction depends on cloud thickness, season, panel orientation and other conditions.

At night: rooftop PV does not produce useful electricity because there is no sunlight driving the photovoltaic process. A battery can supply previously stored energy, and the grid can supply the rest.

This is why annual generation estimates matter more than a single “perfect sunny day” output figure.

Why doesn't every photon become electricity?

Solar cells cannot convert all incoming sunlight into electrical energy. Some light is reflected. Some passes through. Some photons do not carry the right amount of energy to free a useful charge carrier, and energy above what the semiconductor can use can end up as heat. Electrons and holes can also recombine before their energy is collected.

This is also why panel temperature, shading, the angle of sunlight and the electrical design can affect real-world output.

Three things that are not happening

A compact way to remember the process is: light provides the energy, silicon provides the stage, the junction provides the direction, the wires provide the route, and the inverter makes the electricity useful to the house.

Quick solar-panel questions

Are photovoltaic panels different from solar panels?

“Solar panel” is a broad everyday term. Rooftop electricity-producing panels are photovoltaic, or PV, modules. Solar thermal collectors use sunlight for heat rather than producing electricity directly.

Do solar panels create electricity or store it?

They create electrical power from light while the light is available. Storage is the battery's job.

What is the difference between kW and kWh in solar?

kW describes the system's instantaneous power capacity. kWh describes energy generated or consumed over a period of time.

Do solar panels work if the grid goes down?

A standard grid-connected system normally shuts down during a blackout. Backup operation requires equipment specifically designed to isolate the home safely and create a stable supply for the circuits being backed up.

Does more sunlight always mean proportionally more power?

Not perfectly. Irradiance matters, but cell temperature, inverter limits, shading and electrical losses also affect output.

Why is the inverter important if the panels already make electricity?

The panels make DC electricity. The inverter converts it into grid-compatible AC and manages important operating and protection functions.