Solar panels come in a range of sizes and weights, depending on the manufacturer. However, most brands of photovoltaic (PV) modules have similar measurements.
But unless you’ve examined them up close, it can be difficult to understand solar panel size and weight. Before planning a photovoltaic installation, do a little sleuthing to determine whether your rooftop can support PV modules.
On average, residential PV modules are about 65 inches by 39 inches or 5.4 feet by 3.25 feet. Each module typically contains 60 solar cells.
Commercial photovoltaic modules are slightly larger. Standard models generally measure 78 inches by 39 inches or 6.5 feet by 3.25 feet. Commercial PV panels usually contain 72 solar cells.
Although it may seem arbitrary, the size difference makes sense when you understand its purpose. Smaller PV panels are better for maximizing space on residential rooftops, and the larger size makes sense for commercial projects since most commercial arrays have dozens or even hundreds of photovoltaic modules.
Weight is what matters most when trying to determine whether a rooftop can handle a solar panel installation.
Most residential PV modules weigh about 40 pounds each. Some variation exists among photovoltaic brands, however. Weight can range anywhere from 33 pounds to 50 pounds, depending on the manufacturer.
Because of their added length, commercial PV panels are heavier. Most weigh in at 50 pounds or more.
To determine if your rooftop has adequate structural support for PV panels, you must consider the weight load of the entire photovoltaic system.
EnergySage, an online solar information resource, says that the total weight load of the average photovoltaic system — including the PV modules, mounting racks and other hardware components — is about 3 to 4 pounds per square foot.
Both residential and commercial roofs are designed to handle much more weight than that, at least 20 pounds per square foot. However, older roofs and those that have sustained prior damage may not have the necessary structural support for solar panels.
A professional photovoltaic contractor can often determine if a rooftop is capable of supporting PV panels. But solar contractors are not roofing experts, and they cannot guarantee that a roof is structurally sound. If you’re at all concerned about the integrity of your roof, it’s imperative that you schedule an evaluation from a professional roofer or structural engineer.
Just because a roof can support a photovoltaic system doesn’t mean rooftop placement is the best option for you. Some roofs don’t have enough space for a PV array, for example, while others have shading issues that may reduce solar output.
In these cases, your professional photovoltaic contractor can find another mounting solution. For example, ground-mounted PV systems work well for many homeowners and businesses with problematic roofs.
The professionals at Intermountain Wind & Solar offer free consultations to homeowners and businesses throughout Utah, Colorado, Idaho, Wyoming, and Nevada. To explore your options for installing solar panels, contact us today.
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