Solar panels can get pretty big. Considering their size, it’s important to know how big your solar panels are going to be before installing them on your roof. While most modern structures can support the extra weight of a solar panel array, there’s always the possibility of roof leaks and stress fractures stemming from the extra load. For this reason, roof inspections are usually part of the installation process. The size of a solar panel is directly tied to wattage, as a higher power output necessitates larger panels. Depending on the power output and available space, a few large panels can substitute for several smaller ones. But is bigger always better?
Solar panels can weigh anywhere between 15 and 50 pounds, with wattage being the main factor that defines the weight of a solar panel. A 100-watt panel can weigh as little as 14 pounds, while a 400-watt panel weighs about 45 pounds.
Solar Panel Size & Weight
There are several different types of solar panels, each constructed differently, or made from different materials, and thus carrying different dimensions and weights.
Rigid Solar Panels
Solar panels are made up of several layers of materials, including glass, aluminum, acrylic, and the silicon semiconductors. The size of the solar panel is directly related to wattage, which is a function of its size and how many solar cells it contains. Higher wattage solar panels have more solar cells and so are larger overall.
A 175-watt solar panel by Renogy weighs just under 20 pounds and contains 32 solar cells. Renogy’s 320-watt solar panel weighs 40 pounds and contains 60 solar cells. The 320-watt panel has larger dimensions as well, being 65 by 39 inches, compared to 52 by 26 inches for the 175-watt panel.
There’s also a size difference between residential panels as compared to commercial panels. Commercial solar panels tend to be larger and more powerful. The residential version of Sunpower’s X-Series solar panels put out between 345 and 360 watts. They have 96 solar cells and weigh 41 pounds. The commercial X-Series has a power output of 445 to 470 watts. These panels have 128 solar cells and weigh 56 pounds.
Flexible Solar Panels
Flexible solar panels are significantly lighter than their rigid counterparts. They lack the glass and metal frame that makes traditional panels heavy. Instead, they’re encased in durable plastic, which gives them versatility in exchange for durability. This flexible plastic casing allows them to be mounted on curved surfaces like RVs, boats, and tents. Renogy’s 100 watt flexible solar panels weigh just 4 pounds. By comparison, their rigid 100 watt solar panel weighs 4 times as much, weighing in at 16 pounds.
Can Your Roof Support the Weight?
The weight of the solar panels is important when planning a roof installation. Most modern structures built within the past few decades can support the weight of a full solar array, but it’s still important to know the total load on your roof.
Let’s say you are planning to install a 7.2 kW system on your home. The entire array will consist of 20 solar panels with an output of 360 watts. You’ve decided to go with Sunpower’s X-Series, which weighs 41 pounds. With just the solar panels alone, the total weight on your roof will be 820 pounds. These panels are around 60 inches long by 40 inches wide. The full array will be just under 350 square feet, meaning the load on the roof will be about 2.3 pounds per square foot.
The racks and mounts for the panels add weight too. So the actual load will be closer to 3 or 4 pounds per square foot. But the racks and mounts don’t distribute weight evenly. Trusted solar panel installers try to minimize roof leaks by spacing out the mounting points and limiting roof penetration. This can significantly increase the load at certain points. The weight load at these points can exceed 30lbs depending on the spacing and the total number of mounting points.
Snow and ice is another factor to consider. Depending on the slope of the roof, solar panels can collect and hold several inches of snow. This adds significant weight to the roof and can affect stability over the long term. While houses in cold climates are usually made to support the extra weight during the snowy season, a solar array can add several hundred pounds in addition to the snow.
If you live in an older structure, it’s important to assess whether or not your roof can support the extra weight. Roof leaks and stress fractures are consequences of haphazardly installed solar arrays on aging structures. A good solar installer will also survey your roof to determine whether or not it can support a rooftop PV system.
Solar panels can get pretty heavy, but that also depends on the power output. Lower wattage panels can weigh just 15 pounds, while more powerful panels can weigh upwards of 50 pounds each. The weight is dependent on the size of the panels and how many solar cells it contains. More solar cells make for larger panels, which are bigger and heavier but have a higher power output. The size and weight are important when assessing rooftop installations, as space may be limited. The strength of the roof also comes into play as well.
Structures built in the last 30 years are generally able to support the weight of a rooftop PV system, but older homes might not be suitable for rooftop installations. It’s also important to factor in the extra weight from snow cover during the wintertime. If you are unsure if your roof will hold the weight of a solar array, make sure to get a roof inspection from local roofers or a trusted solar installation company. And if you’re really concerned about the extra weight on your roof, you can always install solar roof shingles instead!, or make renovations to turn your house into a passive solar home.
Frequently Asked Questions
Solar panels can weigh anywhere between 15 and 50 pounds. Solar panels are made of several different materials, like aluminum, glass, acrylic, and silicon. These all add considerable weight to the solar panel.
The size and weight of a solar panel are directly tied to its power output. More powerful panels contain more solar cells, so they’re larger in size. A 100-watt panel can weigh around 15 pounds, while a 400-watt panel can exceed 50 pounds.
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