Extreme weather and solar panels
One of the most striking consequences of the climate crisis is the steadily rising temperatures. An outdoor temperature of 40 degrees Celsius had never been measured in the Netherlands before 2019, but we can be sure that such temperatures will become more common. The good news is that your solar energy system is well-resistant to high temperatures: neither the panels, inverter, nor wiring will be significantly affected.
Heat and solar panels: don’t touch without gloves!
You probably already know that solar panels perform less efficiently in the heat. The output of panels has what's called a "negative temperature coefficient." This means: the hotter they get, the lower the output. For most panels, the value of this coefficient is about -0.35% per degree Celsius. In other words, for every additional degree, the output drops by 0.35%, or about 1% for every 3 degrees. That may not seem like much, but keep in mind that panels can get much hotter than the surrounding air. Also, avoid touching your panels with bare hands on a warm sunny day — it could hurt!
Incidentally, the temperature coefficient is not the same for every type of panel. Our SunPower and Q-cells panels have a relatively low value of -0.27%, which means they perform a bit better on hot days than average panels. The temperature coefficient for your type of panel can be found in the datasheets, like this one for SunPower and this one for Q-cells.
Air circulation
Since panels perform better with a bit of cooling, the way they are installed also matters. On sloped roofs, Zonnefabriek always mounts the panels a bit above the roof to allow some airflow underneath. This has two benefits: the panels stay slightly cooler and perform better, and the roof underneath stays cooler too. A nice side effect, because it helps keep your home at a more comfortable temperature.
The panels are mounted slightly above the roof on profiles: the layer of air between the panel and the roof helps keep both the panels and the roof cooler.
Inverters and derating
Besides the solar panels, we also have to consider one (or more) inverters and possibly optimizers. The inverter is packed with electronics and is therefore sensitive to high temperatures. Many of the internal components of an inverter wear out faster when exposed to heat too often. Many inverters will, to protect themselves, go into what’s called “derating mode” at very high temperatures. That means they reduce their output power to avoid further heating.
In the image below, you can see the derating behavior for an SMA inverter we frequently use — the Sunny Boy 2.5. You can see that the derating behavior depends on the voltage across the string. With a relatively low voltage (fewer panels in series), the inverter starts protecting itself from around 35 °C, while with more panels in series, it maintains full power up to over 50 °C. By the way, most inverters only begin derating at extremely high temperatures, so even during the most recent heatwaves, we haven't had any issues. Relevant documentation for SMA can be found here and for SolarEdge here.
Zonnefabriek prefers to install the inverter inside the home, in a relatively cool spot, and not in direct sunlight. This helps ensure a longer lifespan. The expected lifespan of SMA inverters is already long (20 years or more), but a moderate ambient temperature can help them function smoothly for even longer.
Fire hazard
All that heat on the roof and in the inverter — does it increase the risk of fire? A fair question, but thankfully we can reassure you: according to German research, the chance of a fire caused by a solar power system is only 0.006% (source: Fraunhofer Institute, "Aktuelle fakten zur photovoltaik in Deutschland"). When it comes to fires caused by electrical devices, solar panels and inverters pale in comparison to other appliances. Still, it’s good to be aware: fires from electrical devices account for 1/3 of all house fires. The top 5 culprits are:
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Dryers
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Fridges and freezers
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Dishwashers
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Washing machines
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Power strips
So, the risk of fire from solar panels is very, very small. But that doesn’t mean we shouldn’t try to reduce that risk even further. The most important element here: proper installation. Especially ensuring that DC (direct current) connectors are clicked together correctly. If not, there is a risk of arc faults that don’t extinguish on their own. It’s also essential that all used materials are heat- and fire-resistant. Zonnefabriek only installs high-quality, durable materials and pays extra attention to training and installation.
Other extreme weather
Besides heatwaves, we’ll likely also face more extreme weather events in the near future. Think of heavy rainfall, hail, strong winds, and storms. It's quite a lot for our poor solar panels to endure! With that in mind, it's important to always choose sturdy products that can take a hit. And if something does break, our service department is ready to get everything back up and running as quickly as possible.
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