Do solar panels work better when it is cool?

A cool, cloudy winter day can therefore produce less electricity than a hot, sunny summer day. To understand your solar app, it helps to separate the strength of sunlight from the temperature of the cells.

Sunshine helps and heat takes a little back

Solar panels convert light into electricity. Their rated power is measured under standard test conditions, including a cell temperature of 25°C.

The important word is “cell”. A weather forecast reports air temperature. Sunlit panels can be warmer than the surrounding air, so a 25°C day does not mean the cells are operating at 25°C.

Manufacturers describe the effect using a temperature coefficient. It tells you approximately how much the panel’s power changes for each degree of cell-temperature change.

Here is a deliberately simplified example. Suppose a panel has a power coefficient of minus 0.3% per degree Celsius. At a cell temperature of 55°C, it is 30 degrees above the test temperature. Its power would be about 9% lower than at 25°C under the same light conditions.

That is an illustrative panel calculation. It is not a prediction that your household loses 9% of its annual solar generation. The coefficient differs between models, and sunlight and operating conditions keep changing.

UNSW solar researchers describe module temperature as an important part of performance modelling. Their 2025 conference paper also shows why the surroundings matter: obstructions can affect how a panel exchanges heat with the sky. That supports checking the installation, rather than judging output from the air temperature alone.

Look at energy across the day

A high midday power reading is a snapshot. The electricity generated over the whole day is measured in kilowatt-hours, or kWh.

Longer daylight hours can give a system more time to generate, even when hot cells slightly reduce its efficiency. Cloud, shading and the angle of the sun also affect what reaches the panels.

That is why yesterday’s highest power reading and yesterday’s total energy answer different questions. A sharp peak on a cool day may look impressive while a longer summer day still produces more total electricity.

Compare total kWh for similar weather and seasons, and check the app for alerts. If output has changed unexpectedly, save the dates and generation curves for your installer. A single cloudy day or a lower winter total cannot, by itself, establish that equipment has failed.

A cold morning can suit the panels when the sun reaches them, while shorter winter days still limit total generation. Your heating may also be needed after sunset. Check the generation and household demand together before assuming a cool day should produce a low bill.

Let the installation do its job

Good ventilation around panels helps them shed heat. Roof position, shading and system design also affect performance. Your installer should account for those factors when recommending equipment.

There is no need to chase a slightly higher app reading by trying to cool panels yourself. If output drops unexpectedly, check for system alerts and ask your installer to review the pattern.

For your bill, timing matters as well as generation. Electricity used directly from the roof can reduce imports. Electricity exported earns the applicable feed-in payment. If you’re with ActewAGL, check our solar buyback information (opens in a new tab); otherwise, use the export rate on your own plan. A strong midday reading does not mean the system can supply heating or cooking after sunset.

Next time a bright, cool day arrives, compare the power curve, total kWh and grid imports in your app. They answer different questions: how the panels performed, how much they generated, and how much electricity the household still needed to buy.

For a household comparison, record daily kWh, the power curve, cloud, any new shade and whether the system reported a limit or alert. Keep the roof and inverter configuration consistent. Unless cell temperature and sunlight are measured, the observation can illustrate a pattern but cannot isolate the temperature effect by itself.

Related advice: How do I use more of the solar I already have? · How to choose a home battery

Need help with solar output or your bill

Our solar support and maintenance page (opens in a new tab) explains the support route for systems installed by ActewAGL. If another installer fitted yours, ask that installer for equipment support. For the export rate on an ActewAGL electricity plan, check our solar buyback information (opens in a new tab).

Use more of the solar you already have