How to Find Out if Solar Panels are Too Heavy for Your Roof?

heavy for your roof

While solar panels are a great addition to your roof if your roof can support them, you need to do some calculations in order to determine whether placing solar panels on your roof is safe or not. 

So how do you find out if solar panels are too heavy for your roof? 

Solar panels and equipment weigh 2-4 pounds per square foot of equipment; to find out if your roof is strong enough to support them, you need to find out your roof’s weight capacity, figure out how many square feet of solar panels are going to be installed. 

Once you know this square footage, multiply the number by four. This end number is the number of pounds of solar panel equipment you have, and you ensure that this number is well below the weight capacity of the roof to install them safely. 

Installing solar panels can be a great investment in your home if it is undertaken with consideration and forethought. Keep reading to find out why figuring out your roof’s weight capacity is vital to safely fitting solar panels to it. 

Why Figuring Out Your Roof’s Weight Capacity Is Crucial for Safety

Figuring out what kind of weight your roof can support is the first thing you should do when considering whether to install solar panels on it. 

Not only is installing solar panels on a roof that cannot adequately support them a waste of money, as they will have to be uninstalled for safety, installing solar panels that are too heavy for a roof can lead to the roof collapsing. 

As you can imagine, this has the capability to badly injure or even kill residents living in the
home below. 

Before you even look at purchasing solar panels, you should first determine whether your roof is even capable of bearing their weight. If it’s not, you might find you made a very expensive, very-difficult-to-refund purchase on a whim that is not feasible for the long-term. 

Load Limits for Roofs Are Complex

The load limit or weight capacity of your roof is a complex concept, as it encompasses a lot of factors other than the roof’s design itself, which can be very specific to the home in question. Architecture is a wide-fetched field, and there are all kinds of different types of roofs to consider.

Other factors that affect the load limit of your roof include the following:

  • Structural integrity of the roof: Your roof may have been designed to hold a certain amount of weight, but that doesn’t mean that is necessarily the amount of weight it is capable of carrying.

    Any structural damage to the roof, such as settling in the foundation of the home, wind damage, or unaddressed leaks can have significant negative effects on a roof’s functional weight capacity.

    These issues will have to be addressed and repaired before installing solar panels. If the structural damage is pervasive enough, this may even necessitate the replacement of the roof before solar panels can be safely placed on top of it.

  • Age of the roof: Solar panels can last decades, so you don’t want to install thousands of dollars of brand-new solar panels on an elderly roof that only has a few more years of effective use in it before it will need to be replaced. 

Not only does an old roof not have the same structural integrity as a newer roof, as it is more prone to years of wear and tear that lead to the kinds of leaks and other damage. 

This age-related damage negatively impacts functional weight capacity, and major home
repairs such as roof replacement should be addressed before improvements or renovations like solar panels.

  • Materials used in the roof: Roofs are made of a wide variety of materials, and the weight capacity of those construction materials shapes the final functional weight capacity of the roof itself. 

If you are installing a new roof in anticipation of also installing solar panels, it is worth it to look into different roof materials that will increase the overall tensile strength of the roof structure, rather than simply add extraneous weight.

Some roof materials, such as wooden roofs, are not recommended for solar panel installation due to fire hazards and other risks. 

Standard Roofs Are Strong Enough for Solar Panels

The average household roof is capable of holding roughly 20 pounds per square foot in good working condition. This puts it well below the weight requirements of solar panels, which on their heaviest end only put about four pounds of weight per square foot on the roof.

However, one condition that needs to be taken into consideration is snowfall. In northern climates, large banks of snow on the roof combined with the weight of solar panels can put the roof’s weight capacity over the edge, resulting in a collapse. 

For this reason, while the average roof is more than capable of handling your average solar panel rigging, individual circumstances must be looked at for optimal safety. 

Careful Installation Is Important to Preserve Roof Integrity

One issue when installing anything in the roof of your home is that you want to maintain as much structural integrity of the roof as possible Any kind of drilling holes, no matter how small, can introduce moisture to the interior structures of the roof.

Since many houses are wood-based structures that also contain plaster and other materials that are susceptible to water damage, this can introduce leaks into the house’s roof that may not be discovered for months or even years.

By the time a leak is discovered, there is sometimes significant water damage done to the roof, and in homes with attics, this can lead to items in storage being destroyed by water damage
as well. 

Because water damage not only damages the structure of the home but also reduces the weight limit of the roof, it’s vital that the amount of mounting locations in your solar panel rigging is minimized as much as possible, and that any punctures made to the roof are properly sealed. 

Weight Must be Distributed Evenly 

Not only do you have to pay attention to the overall weight capacity of your roof, you also need to look at where your panels are going to be mounted. 

For a roof’s load limits to hold true, any installations on the roof need to avoid pressure points as much as possible. These are areas of significantly heavier weight that negatively affect tensile strength. In extreme cases, a particularly bad pressure point can cause structural damage. 

Solutions for Determining Roof Weight Capacity

On a project as intensive and potentially expensive as a solar power installation, you don’t want to just wing it. On newer roofs made of composite materials or other modern materials, it can be safely assumed that the roof will be able to easily withstand the weight of a solar panel setup.

However, if you have any questions at all about whether your roof can safely hold a solar panel system, you have a couple of options. 

Roofing Company

If you intend to wire in your solar panels yourself and simply want to know if your roof’s structural integrity can handle the weight of the solar panels and their mounting fixtures, you always have the opportunity to call a roofing company.

A roofing company can send out a representative to determine the condition of your roof and whether or not it is suitable for the weight-bearing needed for solar panel installation.

If your roof is not determined to be stable or strong enough to install solar panels, a roofing company can also give you some estimates or quotes on roof repair or replacement, which will need to be undertaken before solar panels can be safely installed. 

Solar Power Installation Company

Rather than calling a roofing company, if you have one locally available you can always contact a solar power installation expert. These companies are popping up all over the world and are now available in many areas to help take over the installation of a solar power grid. 

The good thing about contacting a solar power company is that not only can they usually assess your installation point and determine if solar panels are a feasible option for you, they can also do the installation, which means all you have to do is sit back and watch the magic happen. 

For homeowners who are concerned about faulty wiring, electrical fires, and other similar concerns, hiring professionals to do the job can ease the mind a lot, and let the homeowner focus on bolstering their off-grid initiative through other projects. 

The Weight of Solar Panels

The weight and general size of solar panels may vary according to the manufacturer and the solar panel’s primary intended function. 

Despite this, many brands of photovoltaic (PV) solar panel modules currently on the market have measurements that are a lot alike if not exactly an industry-wide standard, which is convenient for the potential buyer when trying to determine their general weight load.  

Before installing solar panels themselves, very few people have seen them up close, so it’s hard to wrap your head around exactly how large and heavy they are. 

The dimensions of a typical PV solar panel module are as follows:

  • Approximately 65 by 39 inches
  • 5.4 feet by 3.25 feet
  • Contains 60 solar cells

These dimensions break down to roughly 2-4 pounds per square foot, with a total weight of around 42 pounds per module. 

Weight can range as low as 33 pounds and as high as 50 pounds, so determining the weight of each module prior to purchase is recommended before buying them for your roof. When in doubt, measure conservatively and buy less solar panels than the maximum load for your roof.

Commercial solar panels are slightly larger and tend to contain 72 solar cells, but these solar panels are typically too large and expensive for domestic use. 

Different Components of Solar Panel Weight

If the weight of a solar panel was judged just by the solar cells themselves, the solar panels would actually only be a few grams. 

The heavy construction materials used in solar panels that increase each panel’s weight to several pounds include the following components:

  • Aluminum frame
  • Tempered glass cover
  • Encapsulation foil
  • Polyvinyl fluoride backsheet
  • Junction/electrical box

As you can see, it isn’t the solar cells themselves that put a strain on your roof. Rather it’s the various materials used to contain them. If your roof is weak or structurally compromised in some way, stacking a bunch of aluminum and glass on top of it probably isn’t going to help. 

Ground Mounting is an Option

If you have had your roof evaluated by a professional and determined that it is not strong enough to bear the weight of a solar panel setup, you have a few options available to you:

  • Replace the roof. This is by-far the most expensive option, but honestly if your roof is in bad shape you probably need to undertake this anyway. This will allow you to move forward with your original installation plans.
  • Ground-mount your solar panels. If your solar panels are too heavy for your roof and replacing or reinforcing it is not currently an option due to housing codes or other extenuating circumstances, you can always choose to ground mount your panels. 

If the conditions of your roof prevent you from being able to install solar panels, a ground-mounted system is always an option. Ground-mounting your solar panels rather than mounting them on your roof has the following advantages: 

  • Angle: Depending on how your house was built, your roof may not have an optimal angle for good solar energy generation; ground mounted systems can be placed wherever they work best.
  • Efficiency: Solar panels installed on roofs tend to get overheated in comparison to ground-mounted panels, since ground-mounted panels have better ventilation, with air that circulates completely around them rather than just over the top of them.
  • Easy maintenance: If your roof-based solar panels start acting up, fixing them can require getting up on the roof yourself or calling a professional to service them, which is never cheap. But ground-based solar panels are easier to service and clean up.
  • Panel life: Solar panels last for a long time, up to twenty years.

    This is great if you’re considering them for a long-term financial investment to increase the value of your home or reduce energy consumption, but not so great if your roof is about three years from replacement.

    If you are wanting solar panels now but won’t need or want to replace your roof for another few years, a ground-based system can be used instead.
  • Expansion: Due to the nature of installing solar panels on a roof, there is rarely room to add on later if you want to increase the functionality of your setup.

    However, with a ground-mounted system, you can add on as much to your solar power bank as you have the acreage for. 

Advantages of Roof Based Solar Panels

While ground-based solar panels are an option if you determine that your roof can’t handle the weight of solar panels, if your roof is strong enough to install solar panels, you can be the recipient of many benefits. 

The following are significant advantages to installing a roof-based solar panel:

  • Solar panels on the roof are not affected by ambient shadows cast by tall trees or other nearby structures.
  • Rooftop solar panels help protect a roof by shielding it from the elements, such as direct sun and rain, as well as debris such as fallen leaves. Because rooftop solar panels also shade the roof, they help increase the overall energy efficiency of the home.
  • Rooftop solar panels are aesthetically pleasing. While ground-based solar panel systems can be considered an eyesore by some, putting your solar panels on the roof makes them less conspicuous.
  • Rooftop solar panels keep you from having to utilize valuable yard space to house your solar power system, and you won’t have to worry about mowing around it.
  • Rooftop solar panels are long-lived and typically involve a one-time financial investment (though this is true of rooftop panels as well as ground mounted systems).

Installing Solar Panels on Your Roof Is Worth It

Looking into installing solar panels on your roof is well worth the effort. Not only can you save a lot of money on home electricity use and even earn back tax rebates, every little bit of effort helps when it comes to fortifying the natural environment and conserving energy. 

Unlike other human structures, solar panels rarely interfere with wildlife because they are usually installed on pre-existing structures, and the solar power industry helps invigorate the economy by providing thousands of jobs every year.  Renewable energy protects the public welfare by diminishing pollution, uses less resources than fossil fuels, and works just as well during droughts and heat waves as it does during wet seasons, making it an optimal tool to combat growing levels of climate change in the world.

spgenie

Hi I'm Harris the spgenie! As an engineer, I found myself doing tons of research about solar power, the types of panels, how to store the energy and the best way to finance the project. I thought I'd start this blog to share my findings. I hope you find this useful.

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