Heatwaves: Do they affect solar panels?

Adverse effects of heat on solar panels

Although the sun is the main ally of photovoltaic energy, excessive heat can reduce its efficiency. Find out how:

Output voltage decreases

As the temperature of the photovoltaic cells increases, the voltage they generate decreases. While the electric current may remain stable, the reduction in voltage results in lower overall electrical power, which means less usable energy.

Lower conversion efficiency

Heat affects the panels’ ability to convert sunlight into electricity. This phenomenon is known as the temperature coefficient, and each panel has a specific value (e.g., -0.4%/°C). This means that for every degree the temperature rises above the standard, the efficiency drops by that percentage.

Degradation

Constant exposure to extreme temperatures can accelerate the wear of the materials that make up the panel, especially the encapsulants (materials used to protect the panels), as well as various welds and connections. This deterioration not only affects productivity but also shortens the system’s lifespan, reducing its long-term efficiency.

Tips to mitigate the impact of heat on solar panels

Fortunately, there are several strategies we can adopt to counteract the effects of heat and maintain photovoltaic performance, even during a heatwave:

Less heat-sensitive materials

When choosing solar panels, it is important to opt for materials with a lower temperature coefficient, such as the latest generation of monocrystalline silicon technologies. These models perform better under high-temperature conditions and maintain their efficiency in more demanding environments.

Optimal design of solar panels

The design of the panels plays a significant role. Good ventilation between the structure and the roof surface helps disperse heat and prevents thermal build-up. Additionally, installations with sufficient space for air circulation can make a significant difference in performance and efficiency. This is why considering this factor during the initial design phase before installing solar panels is very important.

Cooling systems

As we have already seen, there are passive and active solutions to cool the panels. Passive methods include the use of raised supports and natural ventilation, as previously mentioned. Active systems, although less common in domestic installations, use water or forced air to cool the modules in extreme conditions—particularly in large solar plants.

Considering orientation

An appropriate orientation allows you to make the most of solar radiation while avoiding direct heat during the hours of highest thermal intensity. For the Iberian Peninsula, it is generally recommended to have a southern orientation with an inclination between 30° and 40°; however, each location has its own specific recommendations.

Reflective coatings

Applying reflective materials or special coating technologies can help reduce heat absorption while allowing sunlight to enter. These treatments are quite common and help keep internal temperatures lower by protecting the more sensitive layers of the panel. 

And what about the energy produced in summer?

Although heat can negatively affect the energy efficiency of our solar panels, the good news is that summer also brings more hours of sunlight. This partially offsets the performance loss. While the system may not reach its maximum potential during these months, the vast majority of installations still produce significantly more energy than they do in colder months.

Therefore, if you have a photovoltaic system or are considering installing one, don’t let heatwaves become a concern. With proper design, suitable materials, and careful planning, your system will continue to operate reliably and sustainably, even during the hottest days of the year.