How Weather Affects Solar Panel Efficiency (And How to Optimise Performance)
When investing in solar panels, most homeowners assume that clear, sunny skies are essential for performance. While solar panels thrive in direct sunlight, the reality is that various weather conditions — including shade, cloud cover, and temperature — all influence how efficiently your system performs.
The good news? There are practical ways to optimise your solar output, whatever the weather.
Cloud Cover: Not the End of Solar
Contrary to popular belief, solar panels still generate electricity on cloudy days — just at a reduced rate. Depending on cloud density, output can drop to 10–25% of peak performance. However, with technologies like Maximum Power Point Tracking (MPPT) and microinverters, modern systems can continue to harvest energy more efficiently during low-light conditions.
Optimisation Tip:
Use microinverters or power optimisers to ensure each panel performs independently, preventing underperformance in one area from affecting the whole system.
Shade: A Small Obstruction, Big Impact
Even partial shading from trees, chimneys, or nearby buildings can significantly impact solar efficiency — especially if your panels are connected in a string system. A shadow on just one panel can lower the output of an entire string of panels.
Optimisation Tip:
Position panels in the least shaded area of your roof.
Trim back trees or branches that cast shadows.
Invest in microinverters to isolate shaded panels and maintain overall output.
Temperature: Hotter Isn’t Always Better
While solar panels need sunlight to generate power, high temperatures can actually reduce their efficiency. Most panels perform best at around 25°C; for every degree above this, efficiency can drop by 0.3–0.5%. So, while a hot summer day may seem ideal, it can slightly reduce output.
Optimisation Tip:
Choose panels with a low temperature coefficient, which means less performance loss in heat.
Ensure panels are properly ventilated with airflow underneath to help cool them naturally.
Consider lighter-coloured roofing or tilted mounts to improve heat dissipation.
Rain, Hail & Snow: The Lesser Concerns
Rain actually benefits solar systems by naturally cleaning your panels, removing dust and dirt that can build up over time. Hail and snow, while more region-specific concerns, are generally accounted for in panel durability standards.
Optimisation Tip:
Choose panels tested and certified for hail resistance (IEC 61215 standard).
Install panels at an angle so snow can slide off easily and not block sunlight.
Smart Monitoring for All Conditions
No matter the weather, one of the best ways to optimise performance is with smart monitoring tools. These allow you to track panel output in real time, spot issues early, and adjust energy usage based on solar production.
Solar panel efficiency is influenced by more than just the sun — but that doesn’t mean your system can’t perform consistently year-round. By understanding the effects of shade, temperature, and cloud cover, and taking steps to mitigate them, you can maximise your return on investment and enjoy reliable, green energy — rain or shine.
Get in touch today to start our journey together.
Stay committed!
Damien Frearson
