Installing solar panels on the roof is the configuration chosen by most Filipino households. This preference is easy to understand given the numerous advantages it offers: the use of unused space, discretion, and optimal exposure.

However, it’s important to keep in mind that the weight of a photovoltaic system can be considerable. An excessive load that puts too much stress on your roof structure can quickly compromise its integrity, and therefore the safety of your home. That’s why it’s crucial to verify in advance, how much do solar panels weigh, that your roof can support the weight of your future solar array without weakening, and this for a period of up to 50 years (the lifespan of a solar panel).

In this article, SolarLab will therefore talk about the average weight of a solar panel and a photovoltaic park, we will explain how to calculate the weight of your solar panels and how to best size your power plant, and we will give you our recommendations if your roof is not strong enough to support the load of your installation.

Key points:

• Solar panels that are too heavy for your roof structure can cause damage to your roof and the rest of your house.
• Solar panels that are too light or poorly secured can be moved or damaged by bad weather.
• The average weight of a solar panel is between 20 and 25 kg.
• It is possible to install solar panels on the ground, on a facade, or on shade structures if your roof frame is not strong enough to support their weight.

Why is the weight of a solar panel important?

The weight of your entire solar installation is a crucial safety factor, both for the photovoltaic array itself and for the structure of your house. Excessive weight can put undue stress on your building and potentially damage it in the long run. But, and this may surprise you, a solar array that is too light can also pose a risk. Let’s take a closer look.

The consequences of excessive solar panel weight

An overly heavy installation can lead to serious safety risks for your home:

• Damage to your roof, including cracks, sagging or even a collapse of part or all of your roof.
• Leaks caused by potential deformations or cracks in your roof covering can lead to problems ranging from mold growth and electrical malfunctions to the deterioration of building materials (wood, plaster, etc.) and insulation.
• Damage to the rest of the building (walls, beams, woodwork, etc.). This then threatens the overall stability of your home.

As you can see, the consequences for the safety and lifespan of your home are very significant, and the costs generated by the work needed to repair this potential damage can be considerable. 

The consequences of being underweight

If your solar panels are too light, this will obviously not have any negative consequences for the structure of your house. However, an insufficient load can affect the stability of your installation and its resistance to the elements.

Therefore, strong winds or storms can move your modules, changing their orientation and tilt without your knowledge . These two settings are crucial for ensuring the productivity of your solar panels: randomly varying their tilt angle and the direction they face immediately reduces their production capacity, and therefore their profitability.

In the worst-case scenario, excessively strong winds can even tear the modules off your roof , damaging elements of your photovoltaic system (panels, supports, wiring, etc.) as well as your roof covering (tiles, slates, etc.).

The weight of your solar panels must therefore be taken into account when planning your solar project to avoid any structural risks to your home and your photovoltaic system. Don’t worry: we’ll explain everything in this article to help you calculate this figure accurately. But before that, let’s start with the heart of the matter: how much does a solar panel weigh?

What is the average weight of a solar installation?

Weight of a solar panel 

The weight of solar panels varies depending on several criteria, including:

• The type of panel: thermal photovoltaic or hybrid photovoltaic
• The power output in Wp (Watts-peak)
• The brand and model
• The technology used ( PERC , Bi-facial, water hybrid, aerovoltaic, etc.)

That being said, the average weight of a photovoltaic solar panel is generally between 20 kg and 25 kg.

Weight of a solar panel per square meter

It may be more useful to consider the weight of solar panels per square meter rather than per panel. This figure is often more practical for calculating the size of your solar installation based on the available surface area on your roof. As a reminder, a photovoltaic module is on average 1.7 m².

The average weight of a solar panel per square meter is generally around 12 kg/m² and 14 kg/ m².

Weight of a solar thermal panel

Note that the weight and size of a solar thermal panel are much larger than those of a photovoltaic panel: expect on average between 35 kg and 40 kg for a surface area of ​​nearly 2 m².

Weight of a hybrid solar panel

The weight of a hybrid solar panel is generally closer to that of a photovoltaic module. However, expect between 25 kg and 30 kg per hybrid panel.

How can I determine the weight of a solar panel?

The answer is quite simple: To find out the weight of a solar panel, simply refer to its technical specifications. This is essential information to know when preparing your photovoltaic project, and is therefore logically provided to you before purchasing a module, just like its dimensions, power output, warranties (product warranty and production guarantee), etc.

How do you calculate the weight of a solar installation?

Calculating the total weight of a solar installation is quite simple: you just need to add up the different elements that make it up, namely mainly the solar panels and the mounting brackets.

Calculate the weight based on the number of solar panels

To determine the total weight of your installation, simply multiply these figures by the number of modules you wish to install, or by the number of square meters available for installation.

For clarity, we will focus here on the calculation determined by the number of panels. This is chosen based on the power you wish to install and the unit power of each module.

Let’s take a concrete example: imagine you want to set up a solar power system with a maximum output of 3 kWp and you’ve chosen to buy the monocrystalline 375 Wp panels. To find out how many modules you need to reach 3 kWp, simply divide the total peak wattage of the installation (3000 Wp) by the wattage (Wp) produced by each panel (375 Wp), which gives:  3000 ÷ 375 = 8

You therefore need to install 8 panels on your roof. If you take a quick look at the technical specifications we provide on the product sheet for this panel, you can see that each module weighs 21.2 kg. To find the total weight of your panels, simply multiply this mass by the number of modules you previously determined, which is: 21.2 x 8 = 169.6 kg

Add to that the weight of the mounting brackets, which averages 3 kilos per panel (we will return to this point in more detail in the next section): 

169.6 + (3 x 8) = 193.6 kg Therefore, expect an average weight of approximately 200 kilos for your entire 3 kWp installation.

Remember to include the weight of the mounting brackets.

As we have just demonstrated, it is necessary to take into account the weight of the mounting brackets to determine the total weight of your installation. However, the type of brackets, and therefore their weight, depends on the chosen installation method.

Overlay mounting brackets

Mounting brackets are essential for ensuring optimal tilt and orientation of your solar panels, as well as maximum safety in inclement weather. They must therefore be robust and offer excellent stability, which implies a significant weight. Allow an additional three kilos for each module.

Mounting brackets

Installation involves removing part of your roof covering (tiles, slates, etc.) and replacing it directly with your solar panels. This method requires the installation of a waterproofing membrane, which adds an additional weight generally around 10 kg/ m² . Therefore, expect an average weight of 38 kilos per panel when integrated into the building.

Mounting brackets for flat roofs

The installation of solar panels on flat roofs is done by means of the installation of weighted trays, which by definition must weigh a significant amount to ensure the stability of the modules in case of strong winds.

These weighted trays for solar panels generally weigh between 50 kg and 80 kg, or an average of 40 kg/ m².

What to do if the solar installation is too small?

Is your solar array too light to withstand the elements? Don’t worry, this is a fairly simple problem to fix: you just need to add weight to your panels so they don’t move or blow away in strong winds. However, be careful to calculate the weight of your ballast correctly to avoid the opposite problem, namely adding too much weight that could damage your roof structure.

We recommend consulting a photovoltaic expert to advise you on the best configuration for safely ballasting your solar installation.

What if my roof cannot support my solar panels?

If your roof structure is not strong enough to sustainably support the solar installation you wish to install, there are alternative solutions for installing your photovoltaic panels.

Install the solar panels on the ground or on the facade

If you have land available, the simplest solution to avoid weight issues is to install your solar panels on the ground. This solution offers the dual advantage of being easy to install and securely fixed using weighted supports, just like for flat roofs. However, this comes with two drawbacks: it takes up more ground space and you are ineligible for government subsidies.

Install solar shade structures

Solar canopies, in other words photovoltaic carports, solar verandas and solar pergolas, are excellent options for installing photovoltaic panels without putting excessive pressure on the roof of your residential building.

Turning to other photovoltaic solutions

If you don’t want to clutter your floor space or simply don’t have a suitable plot of land, there are other options for producing and consuming your own green energy. Here are a few.

Solar tiles

Solar tiles and solar slates are a lightweight and aesthetically pleasing alternative to photovoltaic panels. However, it’s important to keep in mind that they are less productive and significantly more expensive than traditional modules. The profitability of your installation will therefore inevitably be affected.

Choose flexible and ultra-thin panels

Flexible panels, also called flexible or semi-flexible panels, have the major advantage of being much lighter than conventional sensors. Expect to weigh between 1 kg and 3 kg per panel.

However, their production capacity is much lower than that of standard photovoltaic modules, which is why their use is generally reserved for supplementary production (small lighting, charging or powering low-energy-consuming equipment) or nomadic use (motorhomes, boats, etc.).

Conclusion

The weight of solar panels, and more generally the weight of the entire installation, is a factor too often overlooked by prospective electricity producers when planning their photovoltaic project.

However, as we have seen throughout this article, it is a crucial factor in the safety and durability of your power plant and your home, and should not be underestimated.

To be 100% certain of your roof’s load-bearing capacity, don’t hesitate to contact a roofing professional or a photovoltaic installer, who will be able to answer all your questions and provide a reliable, personalized assessment based on your building’s constraints and your production goals.