Although solar consultants will be able to help you figure out the logistics of how solar panels will fit on your home, if you want to do some research on your own, you’ve come to the right spot. This post will detail different kinds of loads and the numerous other factors regarding solar panels and rooftops.
Will My Roof Support the Weight of Solar Panels?
When people start to think about buying solar panels for a home, they might look at the size of the solar panels and wonder if the roof was really intended to hold that kind of weight. Fortunately, for their size, solar panels do not weigh very much, and only take up a small amount of the load that nearly every modern roof is designed to bear.
What’s more, the solar panel racking stabilizes the PV system atop your roof. With a better understanding of the ways that solar loads are calculated for the average roof, buyers will know how to determine whether their home is ready for the solar panels they want, or whether they need to undergo a re-roofing process to make rooftop solar a possibility for them.
Dead Load and Rooftop Solar Considerations
A roof is built to take on quite a bit of pressure without collapsing or losing shingles. Heavy winds or snow are common in many parts of the country, which underscores the need for homeowners to have a roof that will stay up during those conditions. The ability of a roof to shoulder weight is determined by its dead load and live load.
A dead load is the weight of the roof itself, plus any permanent structures installed on it (e.g. solar panels). The maximum dead load depends on the roofing material and could range from 15 lbs per square foot (psf) for asphalt, to more than twice as much for clay or concrete style tiles. When actuaries calculate home insurance rates, they figure the dead load into the equation, including live load, which is detailed below.
Live Load and Solar for Home Considerations
In addition to having a minimum specified dead load for permanent aspects of the roof, each roof also has a live load to provide extra support for temporary weight on the roof. Live loads could involve anyone up on the roof cleaning or installing, but also include heavy snowfall.
In areas with a cold winter, a roof might be designed to shoulder a dead load of 20 psf, plus a live load of 20 psf. A sharp slope to a roof could decrease the maximum live load to 15 psf, but almost any well-built roof is designed to carry a great deal of weight. After all, 20 psf of fresh snow might be as much as four feet, which a roof can typically hold without collapsing. Your solar engineers will be able to factor this into their assessments.
Average Size and Weight of Solar Panels
When people start to think about the heavy weight that a long winter of snow might place on a roof, the mass of solar panels feels like taking a load off. Relatively speaking, solar panels are quite lightweight and designed to sit on a roof for decades without causing damage or unnecessary collapse of the roof.
The average solar panel measures about 65 inches by 39 inches, and weighs around 35-45 lbs. If they are installed by a technician experienced in working with different kinds of roofing material, each panel will be placed to distribute the weight and minimize the dead load at any single point in the roof.
Other Roofing Factors to Consider When Thinking About Rooftop Solar
Of course, there are also other factors that interested buyers should keep in-mind before they arrange to have solar panels installed. A roof’s dead load and live load are determined by its construction and material, but also its condition.
A roof that has sustained water damage in the rafters, or has a roofing material that needs replacing, may require repair to be able to support any additional weight placed on it.
Buyers who are thinking about replacing their roof sometime in the next several years may want to complete this task first, as roofing repair or upgrades are more complicated after solar panels have been installed. However, a roof that is well-built and maintained can almost certainly handle the weight of solar panels, with proper installation and care.
The weight of solar panels may be nothing compared to the burden of snow or ice after a huge storm. Almost any roofing material can handle this minimal extra weight, even for many years. Knowing how roofing is supported helps buyers to decide whether solar panels could be right for their homes.