How Temperature Affects Solar Panel Performance

Why Temperature Matters for Solar Panels

Most people assume that the hotter the sun, the better solar panels perform. But in reality, solar panels generate electricity more efficiently in cooler conditions with plenty of sunlight. As temperatures rise, panel efficiency drops, meaning you’ll get slightly less energy from the same amount of sunshine.

This effect is especially important in Australia, where summer temperatures often exceed 35–40°C.

The Science: Temperature Coefficient Explained

Every solar panel has a specification called the temperature coefficient. This tells you how much power output decreases for every degree Celsius above 25°C (the industry standard testing temperature).

• Example: A temperature coefficient of –0.35%/°C

• At 35°C (10°C above standard), the panel’s power drops by about 3.5%.

• At 45°C, the drop is around 7%.

So, while solar panels still work in hot weather, they aren’t producing at their absolute peak efficiency.

Real-World Impact in Australia

• Summer: High panel surface temperatures can exceed 60°C, leading to noticeable efficiency losses.

• Winter: Cooler air temps improve efficiency, which is why solar systems often run closer to their rated capacity in mild weather.

• Cloudy vs Sunny: On bright but cool days, panels can sometimes outperform their nominal rating because efficiency is high.

How to Mitigate Heat Loss in Solar Panels

The good news is that proper system design and installation can help reduce the impact of heat:

1. Choose Panels with Better Temperature Coefficients
   High-quality modules (such as SunPower or premium monocrystalline panels) have lower negative coefficients, meaning they lose less performance in the heat.

2. Install with Adequate Airflow
   Mount panels with enough clearance underneath to allow natural cooling airflow. Roof-mounted panels should have a gap between the panel and roof surface.

3. Consider Panel Colour & Backing
   Panels with lighter-coloured backsheets often absorb less heat than black-framed modules.

4. Regular Cleaning
   Dust and dirt can increase heat build-up. Clean panels not only capture more sunlight but also run slightly cooler.

5. Use Micro-Inverters or DC Optimisers
   These technologies can minimise the impact of heat on overall system performance by optimising each panel individually.

6. System Oversizing
   Designing your system with a little extra capacity can help ensure that even on the hottest days, you still generate enough energy for your needs.

Key Takeaways

• Solar panels are more efficient in cooler temperatures.

• Expect some performance drop in hot Australian summers, typically around 5–10% depending on conditions.

• Choosing the right panels, ensuring airflow, and maintaining your system can help minimise losses.

✅ Pro Tip: If you’re shopping for panels, compare the temperature coefficient in the datasheets. A panel with –0.29%/°C will perform better in the heat than one with –0.45%/°C.