It’s a scorchingly hot summer day. The sun is out and is showing no signs of hiding behind the clouds or turning down the heat. All you can do is sip your iced coffee under the shade.
This must be the best and most efficient time for your trusty solar panels, right?
Well, not exactly. It’s a common misconception that hotter days mean stronger sunlight for the panels to convert into electricity. On the contrary, too much heat hinders their capacity to collect energy.
One way to understand it is to imagine yourself running a marathon on a sweltering 90°F day—tough, isn’t it? If the temperature had been a cooler 70°F, it would’ve been easier to run.
In the same way, solar panels perform better in converting the sun’s rays into energy when they’re at an optimal temperature. An increase in temperature beyond that reduces your panels’ voltage, power output, and efficiency.
So, what optimal temperature do your solar panels need to perform at their best? Can we measure the drop in the panels’ efficiency whenever the weather gets too hot? Is there a way to reduce the negative effects of heat and keep your solar panels functioning to the fullest?
We’ll tackle all these questions and more in this guide, so keep reading!
The Bright Side of Cool Weather: How Heat Affects Solar Panel Efficiency
Temperature affects electronics of all kinds, and solar panels are no exception.
The optimal solar panel performance temperature is 77°F or 25°C. It’s the industry standard, and most, if not all, solar panels are designed to produce energy most efficiently within this temperature range.
However, when heat warms up your solar panels above this optimal temperature, their efficiency starts dropping, no matter how bright the sun may shine!
This has something to do with the laws of thermodynamics, the science of energy transfer.
Basically, excessive heat energizes the electrons on your solar panels, causing them to react differently and pick up less energy than they usually do at a cooler temperature. This reduces the amount of electricity that’s generated. It can lower the efficiency of your panels by 10–25%.
This means that solar panels are most efficient in sunny and cool climates rather than those with extreme heat and desert-like conditions.
Since solar panels are installed in places all over the globe, with varying climates and ever-changing weather conditions, it’s important to understand the drop in their energy production whenever the heat rises above optimal levels—known as the temperature coefficient.
Understanding Your Solar Panel’s Temperature Coefficient
So, what happens to your solar panel’s energy production when it gets too hot?
The temperature coefficient will tell us that. It’s the percentage decrease in your solar panel’s energy production whenever the temperature increases above optimal (77°F or 25°C).
For example, if your solar panel’s temperature coefficient is –0.5% per degree Celsius, this means that the solar panel’s efficiency drops by 0.5% for every degree that the temperature rises above 25°C.
The closer the temperature coefficient is to zero, the better. It shows that the solar panel is less affected by heat and performs better in hotter temperatures.
Manufacturers produce solar panels with varying temperature coefficients, but most of them fall within the range of –0.2% to –0.5% per degree Celsius. You can always find the temperature coefficient value (Pmax) listed along with your solar panel’s specs and other product details.
How to Reduce the Effects of Heat on Your Solar Panels
At this point, you may be wondering: Is there anything I can do to stop my solar panels from getting too hot? How can I optimize the efficiency of my solar panels?
There are many practical ways to minimize heat and its negative effects on your panels and several strategies to maximize efficiency, including:
1. Observe Proper Spacing and Installation
If possible, install your solar panels in a spot with plenty of natural ventilation—harness the cooling powers of the wind!
When mounting your solar panels, leave at least six inches of space in between the panels and your rooftop to allow sufficient airflow, keeping your panels cooler. At the same time, avoid having a gap that’s too large, as this can cause leaves and debris to collect under your panels.
Install at an optimal angle that maximizes your panels’ sunlight exposure while also reducing the chances of overheating.
You can also put electronic components like your inverter and combiner on the shaded area behind the panels to further reduce heat absorption.
2. Choose Light Colored and Reflective Materials
Specific types of roofing materials, such as metal, are great at reflecting sunlight, helping your solar panels remain cool. It’s one option to consider if your roof is old and needs replacement.
White or light-colored materials and roofing with reflective coating are also recommended, as they’re highly beneficial in lowering the temperature around your solar panels.
While all-black panels are popular for their aesthetic appeal, lighter-colored solar panels remain cooler for longer. The darker the color of the panels, the more heat they’ll absorb.
3. Use Active Cooling Systems
Another highly effective way of reducing heat is to install additional ventilation, including fans that circulate air beneath your panels to keep them cool.
You can also use heat sinks, components designed to properly remove heat from your solar panels and help them maintain an optimal temperature.
Some specially designed systems pass a cooling liquid underneath your panels to remove heat from their surface, in the same way our bodies are designed to sweat to cool us down!
If you need help in deciding which cooling system is best for your needs, don’t hesitate to consult an experienced solar panel provider in your area.
4. Select the Right Solar Panels
If you’re still searching the market for the right solar panel or planning to add more panels to an existing system, remember to choose a model that has a low-temperature coefficient.
Solar panels with low-temperature coefficients still function efficiently even when the heat intensifies. They’re best suited for areas with warm climates.
Ground-mounted solar panels are also a good option if you live in a particularly hot environment. As its name implies, this type of solar panel is mounted on the ground using poles or racks.
Because they’re closer to the ground, these panels are usually cooler than rooftop panels and can produce more energy.