Solar panels are frequently exposed to high amounts of heat, especially during the longer summer days. Testing for home solar panels occurs at 77°F (25°C), so the general temperature range for solar panels is between 59°F and 95°F (15°C and 35°C). This is when they will produce at maximum efficiency. However, solar panels can get as hot as 149°F (65°C) and this can hinder their performance.
How Does Temperature Affect Solar Panel Performance?
Installation factors such as how close the panels are installed to the roof can impact the typical heat of your solar system. Most solar panels are composed of silicon photovoltaic (PV) cells. These cells are protected by a sheet of glass and held together with a metal frame. These materials are similar to those used for the windows and frame of a car. You can imagine how hot they get by imagining how hot cars get that have been sitting in a parking lot under the sun all day. The windows and frame will be hot to the touch. The actual temperature that your solar panels will vary significantly depending on air temperature, how close you are to the equator, the level of direct sunlight, and roofing material.
How Temperatures Affect Solar Panel Efficiency
You have probably found yourself wondering if solar panels can overheat. This is logical considering they are exposed to extreme heat at times. Just as with any other electronic equipment, solar panel performance does decline as they get hot. The laws of thermodynamics teach us that with increased heat comes decreased power output, and this applies to solar panels. Thus, warmer temperatures will always mean less output for PV cells. This reduced output is quantified in a “temperature coefficient” by panel manufacturers, and this will vary from model to model.
Is it possible for you to know what kind of output losses your panels are experiencing? Manufacturers rate their products’ susceptibility to temperature in the form of the temperature coefficient, which is expressed as a percentage per degree Celsius. The rating is based on testing done on power output at 77°F (25°C). If a panel is rated to have a temperature coefficient of -0.50% per °C, this means the panel’s output power will decrease by a half of a percent for every degree the temperature rises about 25°C. This number may seem small but the average surface temperature of a dark-colored roof in the summer heat can be well above 25°C. The small percentage of output power loss for each degree of heat will be compounded.
Actions to Counteract Overheating
There will always be some energy output loss due to heat no matter which solar panels you get. What is important is that there are several ways to mitigate the effects of hot temperatures on solar panels. Most panel manufacturers use a thermally conductive substrate to house their panels. This helps vent heat away from the glass layers. Solar panels are also typically mounted a few inches above your roof. This leaves airflow space below the actual unit which helps to move heat away from the panels.
Another recent development is thin-film panels. These boast a temperature coefficient rating of between a -0.20 and -0.25. Thin-film panels have a distinct coefficient rating advantage over more traditional monocrystalline and polycrystalline photovoltaic panels (typical temperature coefficient is between -0.26 and -0.50). The downside is that thin-film panels are typically less efficient than their crystalline PV counterparts.
One thing to remember about temperature coefficients is that if a panel is operating in temperatures lower than 77°F (25°C), the temperature coefficient will be positive which means your solar panels will increase in efficiency. The best conditions for optimal solar production are cold, sunny days so you don’t have to live in a warm climate to benefit from solar panel energy. This efficiency gain in cold weather helps to offset the losses that occur during the summer months. If you do live in a climate that is warm and sunny throughout the year, you may want to invest in higher-end solar panels that come with a lower temperature coefficient.
What is the Right Solar Setup for Your Home?
Solar installation experts will customize their system designs to meet the specific needs of each individual property. This design will include the temperatures a roof might expect to see throughout the year. You want to find an installer that’s the right fit for your home and this will take some research. You will want to compare several installation services before you decide.