How hot do solar panels get?

Have you ever left your phone out on a scorching day and received that overheating warning—the one that tells you your phone is too hot and needs to cool down? Solar panels face a similar challenge. Sort of. 

While solar panels can still produce power in the heat, their efficiency drops compared to cooler conditions. Just as your phone warns you when it overheats, solar panel manufacturers note this decrease in output on their product datasheets. 

Imperfect analogy aside, here’s the gist: Solar panel surface temperatures can get up to 149°F. However, they perform optimally in cooler temperatures up to 77°F. The second law of thermodynamics tells us that with increased heat comes decreased power output. Your panels won’t shut off or malfunction if the temps rise to high; they just won’t work as well.

Let’s delve into understanding temperature coefficients, selecting panels best suited for your climate, and comparing some of the top solar panel options available on the EnergySage Marketplace.

Solar panels are composed of solar cells, protected by a sheet of glass, and held together with a metal frame — similar to the windows and frame of a car. Anyone who has sat in a car parked in the sun all day knows how hot the interior surfaces can get, exceeding the warmth of the air outside. The windows and frame heat up, but there’s minimal risk of the car bursting into flames.

The temperature of your solar panels at any given time depends on several factors: Air temperature, proximity to the equator, direct sunlight, your specific setup, and roofing materials. Generally, solar panel temperature ranges between 59°F (15°C) and 95°F (35°C), but they can get as hot as 149°F (65°C). However, the performance of solar panels, even within this range, varies based on temperature and product.

For a technology designed to bask in direct sunlight all day, solar panels are a bit finicky when it comes to temperature. 

Home solar panels are tested at 77F (25C) to determine their temperature coefficient — an indicator of how well panels perform in less-than-ideal conditions (or temperatures above 77F). Temperature coefficients are expressed as a percentage per degree Celsius (i.e., -0.34% /C). So, if a panel is rated to have a temperature coefficient of -0.50% per C, that panel's output power will decrease by half a percent for every degree the temperature rises above 25C (77F). 

Though that may sound like a small number, the losses add up. The surface temperature of a dark-colored roof in the summer can be significantly higher than 77F (just imagine the surface of an asphalt road on a hot summer day). This small percentage loss per degree of heat can gradually chip away at a panel’s efficiency. 

For example, let’s say you install 430-watt REC Group Alpha Pure 2 solar panels with a 22.2% efficiency rating and a temperature coefficient of -0.24% per degree Celsius. If the surface temperature of your roof reaches 30C (86F), the panel’s efficiency will drop to 21.9%. At 35°C (95°F), it decreases further to 21.7%.

Temperature coefficients of popular solar panels

No matter which panels you choose, some efficiency loss due to heat is inevitable. However, advancements in solar technology are continuously reducing the impact of high temperatures on panel performance.

A basic technology employed by most panel manufacturers is to use a thermally conductive substrate to house their panels, which helps vent heat away from the glass layers of the module. Solar panels are also commonly mounted a few inches above your roof, with space for airflow left below the actual unit, helping to move heat away from the modules.

If you live in a cooler climate, the temperature coefficient may not be your biggest concern

We often hear that sunny states like Arizona or Florida are perfect for solar panels—and they are—but you don’t need to live in a warm climate to benefit from solar power. In fact, the ideal conditions for solar production are cold, sunny days. This increased efficiency in cooler weather helps balance performance losses during the hotter months, especially for homeowners in regions with distinct seasonal weather cycles.

If you live in a cooler climate, you might prioritize things like efficiency or backup power over temperature coefficient.

If you live in a hotter climate, a lower temperature coefficient can make a difference

Conversely, if you live in a warm and sunny climate throughout the year, you may want to invest in higher-end solar panels that come with a lower temperature coefficient. REC Group and Panasonic manufacture solar panels with some of the lowest temperature coefficients available in the industry. If you expect your roof’s surface temperature to exceed 77°F regularly, it’s worth seeking quotes from installers who offer these premium panels.

Solar installers customize their system designs to meet each property's specific needs, including the temperatures a roof might expect to see throughout the year. However, if you are considering installing solar panels on your roof, finding the installer that's the right fit may take a little browsing around. Use the EnergySage Marketplace to easily compare multiple offers from vetted solar installers near you.