Investing in solar power requires more than a cost assessment. Before setting up rooftop solar panels for your home electricity generation needs, you should also ensure your roof can support the weight.
The total weight-bearing capacity depends on the size and strength of your roof and the number of panels you need.
Fortunately, most home roofs can comfortably withstand the weight of a solar panel array. A typical residential array will weigh well below the average roof’s weight-bearing capacity. Understanding the factors and how they impact your home structure will help you get the right set-up for your solar energy needs.
The Weight of Solar Panels per M2
Different manufacturers create solar panels of different weights. On average, solar panels weigh between 5 and 10kg per square meter. For a sound roof, this weight won’t threaten the roof’s stability under the panels.
The weight doesn’t spread evenly across the surface of your solar panel. The fixtures where the panels are mounted bear the bulk of the weight for each panel.
Further, the slope of your roof can affect how much of a burden those attachment points create. That said, the weight usually does not burden most residential roofs.
Other factors should weigh into your final assessment. If you live in an area that receives a great deal of snow, the extra weight that uncleared snow creates adds to what your roof has to bear. If you live in a particularly windy area, the gusts can create a lifting effect under the panels; enough force can damage your roof by pulling solar panels upwards rather than pressing down.
Proper solar panel installation is essential to provide the best protection for your home against these potential hazards.
How Much Weight Does a Solar Array Add to a Roof?
By construction standards, the weight solar panels add to your roof usually isn’t a cause for concern. The average residential PV panel measures about 1.65m by 1m. Including mounting equipment will add about 20kg to your roof. For a full 6kW array, you will need about 20 panels, adding about 365kg of dispersed weight.
Fortunately, the weight is distributed across your roof, so no one area bears the bulk of this burden. The key isn’t to worry about the weight added to your roof.
Instead, focus on two factors to allow your roof to remain strong:
- Ensure your roof is in good shape before the installation, with any needed repairs completed before you install solar panels; and
- Consider having experts install your solar panels. Experienced solar installers will know what to look out for and how best to distribute the weight.
As long as you start with a solid roof and have your solar panels installed professionally, the weight of the panels should not create problems for you. If the roof is damaged at the time of installation, it can be much more complicated (and expensive) to complete those repairs after the panels are in place.
How to Determine the Strength of a Roof?
While the solar panels’ weight is relatively low, that is just half of the equation. The roof also needs to be strong enough to bear the weight of any panels you add. It also has to hold the additional weight of snow that may accumulate or people who may have to walk on the roof for inspections, repair, and installation.
Roofers measure a roof’s strength in pounds or kilos per square foot or per square meter. To assess the strength of your roof, begin with the materials used. Both the type of material and the thickness of that material affect the load your roof can bear. An inspection can reveal whether the roof is bowing, warped, or degraded. Any of these conditions can reduce the strength of your roof.
Support structures also factor in here. The number, material, strength, and integrity of any support beams impact the level of support your roof provides for the panels you install.
Before installing solar panels, get a full inspection of your roof and the support structure. You should address any damage, leakage, or structural degradation before you proceed with the installation.
Will Your Roof Be Damaged by Solar Panels?
So long as the structure of your roof remains intact and in good condition, your roof should be strong enough to make any impact from solar panel installation negligible. Neither the weight of the panels nor the strain where brackets are affixed should cause damage to your roof.
If there is damage, it will most likely occur during the installation process. Installing the brackets to hold solar panels in place requires understanding the best practices for affixing the brackets and the panels. Do-it-yourself installations can create problems if you are not a trained professional in this area.
You may also find that installing solar panels voids any warranties on your roof. This void clause protects those who have installed or repaired your roof from being responsible for other people’s mistakes. Most professional solar installations will have a warranty against damage to the roof. If you work with the right people, you should be protected against any damage that might occur.
What Makes Solar Panels So Heavy?
The combined materials that go into the construction of solar panels determine the weight of each panel. Rigid solar panels generally include tempered glass and aluminium as the main components. While each panel is relatively light, the combined solar array does add a weight burden to your roof.
Apart from the weight of the panels, each will require brackets, with the weight of each panel concentrated at the mounting point. The mounting materials are relatively light and designed to distribute the weight safely for each panel and roof area.
Some manufacturers have responded to the need for lighter solar setups by creating flexible solar panels. The technology still uses photovoltaic cells, but an ETFE film and laminated glass fibre make them exceptionally lightweight.
Calculating How Many Solar Panels You Need
As with any energy decision, the number of solar panels you need will depend on your energy usage and needs. To find this, you should learn the following:
- Your current energy usage
- The amount of sunlight you receive in your area
- The efficiency of the solar panels you are considering
- The rated power of the panels you are considering
- The size of the panels and your roof
With this information, you can determine the output you require for your household electricity needs. It’s always best to err on the side of caution and add at least 10% additional wattage to your estimated energy requirements.
Once you know how much electricity you need to generate and how much space you have to install your solar array, you can determine which solar panels are right for you.
Working with a professional installer can help you maximise the placement of your panels to get the most energy from the array you set up.
Installing Solar Panels
Installation of solar panels requires understanding your roof’s structural integrity and how to place and connect the panels. You want to ensure the maximum sunlight exposure in terms of both the orientation of the panels and the shading that occurs over them.
Your solar array will still power your house at night and at other times without sunlight hitting them. Residential solar power solutions like EcoFlow’s Power Kits and Smart Home Ecosystem collect, convert, and store energy, so you don’t need constant sunlight to meet your electricity needs. Instead, you need to ensure you collect sufficient solar power during peak sun hours to maintain the energy delivery you need.
DIY installation options are available but not recommended. Mounting the brackets and solar array isn’t onerous for the average handyperson, but maximising placement comes through experience.
Solar panels do not weigh more than most roofs can comfortably bear. You will need to assess the strength of your roof, your energy needs, and the weight of the complete array required to meet that need. Understanding these factors will allow you to purchase and set up the right size solar system.
Rather than try to go it alone, a solar power expert can help you. EcoFlow has the installation experience and the products that can help you get the most from your conversion to solar power.
Frequently Asked Questions
If your roof is structurally sound, it should have little difficulty managing the weight of your solar panels. Schedule an inspection to ensure that you don’t have internal damage that affects the weight your roof can bear.
The weight of a solar panel varies by manufacturer, material, and construction. An EcoFlow 400W rigid solar panel weighs 21.8kg, whereas a 400W portable solar panel from the same manufacturer weighs 16kg.
A 72-cell solar panel typically weighs between 20-25kg, depending on the manufacturer and the materials used.