Solar panels are a great way to generate renewable energy, and they can be installed on a majority of roofs. However, solar panels are heavy objects that can weigh down your roof if you have a lightweight metal roof.

This article will answer the popular question of 'how many solar panels can I fit on my roof?, and will discuss how suitable solar panels are for different roofing systems.

how many solar panels can i fit on my roof

Types Of Roofs And Their Suitability For Solar Panels

Can solar panels be installed on a metal roof?

Yes!

Many metal roofs are lightweight, and solar panels should not be a problem for them. However, you need to make sure that when mounting solar panels on metal roofs the weight is spread out over more than one part of the roof, to prevent sagging in the middle.

A durable metal roof has the ability to last between 50-60 years, outlasting the average lifespan of a solar panel. This will ultimately eliminate multiple installation fees, as the roof will not need to be replaced along with the solar panels.

Asphalt Shingles

A photo of solar panels on an asphalt shingle roof

Asphalt shingle roofs are particularly common and are one of the most suitable for sustaining solar panels. To install solar panels on an asphalt shingle roof, aluminum profiles are used which are fastened to the roof and provide extra stability for the solar laminates.

Some PV panel installers recommend that solar panels be installed on an asphalt shingle roof because they can withstand water infiltration better than metal roofs. Asphalt shingles also have a lower weight capacity than metal roofs, so they are less likely to cause structural damage.

The only downside of installing solar panels on an asphalt shingle roof is that they have the potential to prematurely wear out faster because of the solar panel's heat output. This means that owners must be diligent, and frequently inspect the PV solar system.

Tile

Installing solar panels on rooftop materials such as tiling is often more expensive than other options, due to the mounting system needed.

Mounting equipment like brackets will need to be used on tile roofs to support the solar panel system, which will effectively lift the panels above the roof.

To install PV solar panels on a tiled roof also comes with a high risk of damage being caused to the waterproof integrity of the roof. This could lead to larger, and more expensive problems in the long term (such as a roof leak). Therefore, the installation costs are increased. 

Concrete

Many solar panel manufacturers recommend not installing solar panels on concrete roofs. The weight of the panels may cause a home to settle, and they can become damaged by extreme weather conditions such as hail (link) or high winds.

PV solar panels on a concrete roof is possible but will require some expensive structural engineering solutions to make sure the solar panels are not too heavy for the roof.

What about PVC?

PVC roofing material is not suited for solar panel installation and creating solar power. Photovoltaic panel systems require a lot of strength from heavy glass pieces, and the weight can cause drooping in high humidity environments.

The shingles are also too lightweight, and the roof structure will have an effect on how much weight each solar panel has for support.

Flat Roofs

Installing solar panels on a flat roof is a popular choice when wanting to create solar power.

The weight is evenly distributed across the roof and does not put any additional stress on it, there's no need to anchor them into the ground with shingles or other materials, and they are unlikely to be blown off by high winds.

A flat roof type solar panel system takes up more room per kW. This is due to the separation gap needed between each panel to prevent shading or blocking - which means this style of installation can often take up as much space on your rooftop when compared with slanted panels.

Should I Consult With A Solar Panel Installer First?

Whether your roof is new or old, it is best to consult with a solar panel installer or a roofing expert to arrange for an inspection to be done of your roof.

A photo of a man installing solar panels on a roof

The expert will be able to assess if your roof is damaged in any way, and can advise on whether PV panels are appropriate for your roof and if it is stable enough.

A solar panel installer can also give you an estimate for the solar panels required, and advise on what solar panel installation style would suit your roof best.

If your roof is damaged in any way and solar panels are still installed, it will likely cause bigger problems down the line. Including solar panel failure, leaks, and a lack of solar energy - which can be avoided by booking an inspection ASAP!

Remember - although the cost savings will bring your power bill down, re roofing your house could wipe out the benefits quickly. If you are the homeowner, we recommend speaking with a professional at the beginning.

How Many Solar Panels Can I Fit On My Roof?

The solar panel size and number of solar panels you can install on your roof will depend on the weight load that it is able to support. For example, a solar panel with an 18-inch width will only be able to hold 180 pounds, while one 20 inches wide could carry 400 pounds.

Roofing experts examine that homeowners can calculate the average amount of PV solar panels they can fit on their roof by multiplying the solar panel's wattage by their roof size in square feet.

However, The average solar panel is 78.74 x 157.48 centimeters and will take up around 1.239-1.44 square meters of space.

Solar Panel Size

Solar panels can be measured in watts, the measurement of solar energy production. The size of a solar panel is dependent on the wattage and will typically range from 15-300 watts.

Different sizes are available for different purposes, but it's important to note that many homes need at least four 100 watt panels in order to produce enough power.

Solar panel weight

The average weight of most residential solar panels is 40 pounds each, this is a key factor when deciding whether your roof is suitable for a solar panel system. Generally speaking, the weight may vary between 33-50 pounds and is dependent on different manufacturers.

Most metal roofs are around 40 pounds per square foot and most asphalt roofs are about 50 pounds per square foot, but it's hard to find a specific number for your own home without measuring.

Is My Roof Too Old for A Solar Panel Installation?

If you have an older roof, it might be too fragile and leaky for solar panels. This would make the installation process more difficult because of safety concerns or increased risk of leaks from damage to shingles and other materials used on roofs.

A photo of an old and damaged roof

A new roof is a more viable option for solar panel installation, but you need to make sure that the roof is structurally sound and capable of supporting heavy weight.

If your roof has been damaged by hail storms (link to my article) in the past few years, it's a good idea to get an assessment done first before installing solar panels.

Do Solar Panels Ruin Your Roof?

Solar panels don't ruin roofs.

They are actually installed on mounting systems that can be attached to the roof or set up away from it, like solar carports. Solar panels require a strong surface for installation and not all surfaces will work.

If the process to install solar panels is not done correctly, your home is at risk as the structure of the building is being altered. The weight of the PV solar could cause long-term damage if installed incorrectly, leading to further repairs later down the line.

Homeowners should only allow a registered installer to complete the roofing system that follows strict safety measures, to ensure the roof stays watertight.