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nce you’ve installed solar panels, you will surely want to know how to keep them efficient. One of the things all newfound solar owners wonder is how strongly PV modules heat up under the sun and what panel surface temperatures are considered normal. Let's dig into it.

Is it dangerous to touch solar panels?

First, let's answer the question: how hot do solar panels get? Usually, PV panels are as just hot as the ambient temperature. So yes, in summer, in the midst of a sunny day, they do become hot to the touch. But think of it that way: the majority of solar panels are made from materials comparable to those that make up the frame of a car – when parking under the sun on a scorching day, the car frame can become hot to the touch, but the risk of burns or fire is very little.

What is the optimal temperature for a solar panel?

For solar panels, the optimal outdoor temperature is about 77°F or 25°C – this is the level at which solar panels are generally tested. The optimal temperature means that they perform at peak efficiency losing the least amount of power output.

One might think that the more sunshine, the higher the solar panel efficiency. But the truth is, higher temperatures actually make solar panels less efficient: they begin to generate less power once the temperature rises above 77°F.

What is the solar temperature coefficient?

The temperature coefficient is the parameter indicating the percentage of power output that is lost by a solar panel as the temperature gets higher than 77°F (25°C). For example, the temperature coefficient of a good solar panel is -0.41% per one degree Celsius. This means that for every one degree Celsius above 25°C (77°F), the maximum efficiency will decrease by 0.41%.

And what's more, for every one degree Celsius below 25°C, the maximum efficiency of that solar panel will increase by 0.41%, as colder temperatures enhance solar energy generation efficiency. The best conditions for optimal solar energy production are cold, sunny days. In general, solar panels have a temperature coefficient of around -0.3% / °C to -0.5% / °C.

Do solar panels overheat at higher temperatures?

In a nutshell, solar panels can indeed overheat, just like any other electronic device. The risk of fire is incredibly small, however. Solar systems pose an extremely low fire hazard, and fires caused by PV panel overheating are very rare. Still, once a solar panel overheats, its efficiency decreases greatly.

How does overheating impact a solar module’s efficiency?

To find out how overheating impacts PV efficiency, let’s briefly look at how solar panels work. Sunlight hitting a solar panel excites electrons in the semiconductor material, creating an electric current. But the higher the temperature of the panel is, the more electrons are flipped to the excited state. This reduces the voltage that the panel can generate and therefore lowers its efficiency.

Higher temperatures can reduce the output efficiency of solar panels by as much as 10%-25%, so scientists are currently trying to figure out how to keep solar efficiency high despite exposure to heat.

Solar owners often wonder if their PV panels can completely fail due to extreme heat. Solar panels can typically withstand temperatures of up to 185°F or 85°C, which means complete breakdown is highly unlikely.

How to counteract solar overheating?

Unfortunately, if the temperature in your region reaches the levels of 40°C – 50°C during the summer season, then your solar panels will not perform at their best. But here are a few tips on how you can at least partly offset the impact of high temperatures.

Space and airflow

Solar panels can cool down by dissipating their heat into the nearby surroundings. That is why when you install solar panels on your roof, some space should be left between the panels and your roof tiles. This allows air to act as a natural cooling system that lowers the temperature of the solar cells.

Water

In addition to airflow, another conventional medium for solar panel cooling is water. This works exactly like sweating: water evaporates away and cools the surface. By wetting solar panels, you also remove any dust or other matter from them, improving their efficiency.

Thin-film panels

Thin film panels are a second-generation solar technology with a temperature coefficient rating of between -0.2% / °C and -0.25% / °C, which is significantly higher than the usual temperature coefficient of traditional monocrystalline and polycrystalline solar panels.

Is it worth paying extra for a premium-brand solar to avoid overheating?

Premium solar panels normally offer a lower temperature coefficient, which means that they lose energy less at higher temperatures than their cheaper alternatives. So if you do not want your solar panels to perform better in heat, you should be ready to pay extra.

But the top tip here is to choose your PV panels based on the climate conditions of your area. If higher temperatures are a regular phenomenon, think about purchasing a more advanced low-temperature option.

Posted 
Apr 4, 2023
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