How Much Do Solar Panels Weigh?

As solar panels become a popular choice for UK homeowners looking to reduce energy bills and embrace renewable energy, understanding their weight and the implications for roof installation is crucial.

This article explores how much solar panels weigh, whether roofs can support them, and other weight-related considerations for solar panel installations and a rooftop solar system.

How Much Do Solar Panels Weigh?

The weight of solar panels varies depending on their size, type, and intended use. Most residential solar panels, which typically consist of 60 cells, weigh around 40 pounds (18 kilograms).

However, some panels designed for commercial applications can weigh up to 50 pounds (22.6 kilograms).

Commercial solar panels typically have 72 cells and vary in weight compared to residential panels. For example:

• Standard Residential Panels: A typical 60-cell panel weighs approximately 18–21 kg (40–46 lbs).
• Commercial Panels: Larger commercial solar panels, such as those with 72 cells, can weigh 22–30 kg (48–66 lbs).
• High-Power Models: Some powerful panels can weigh up to 38.5 kg (85 lbs) due to their larger size and higher wattage (670 W).
• Lightweight Options: Thin-film solar panels, ideal for weaker roofs or mobile applications like caravans, can weigh significantly less, sometimes as little as 2.3 kg per square metre on flat roofs.

Different solar panel sizes impact both the weight and the installation process. Larger panels may require more robust mounting systems and can affect the overall load on the roof structure.

For a typical three-bedroom home requiring 10 solar panels, the total weight of the panels alone would be approximately 180–210 kg (400–460 lbs).

When factoring in mounting hardware, which adds about 15–20 kg per square metre, the total system weight could reach 200–250 kg spread across the roof. Solar panel weight is a crucial factor in ensuring the roof infrastructure can support the installation.

Read more in our guide to the best solar panels right now

Can Your Roof Support the Weight of Solar Panels?

Most modern UK roofs are designed to handle significant loads, including snow, wind, and additional fixtures like solar panels.

The average UK roof can support at least 108 kg per square metre, while solar panels and their mounting systems typically exert a load of 15–20 kg per square metre—well within the capacity of most structures.

Evaluating the weight capacity and structural integrity of roof structures is crucial before adding solar panels to ensure safety and durability.

However, several factors determine whether your roof is suitable:

Roof Condition and Age

Older roofs or those with signs of damage (e.g., cupping, lifting, or corrosion in metal or asphalt shingles) may require repairs or reinforcement before installation. A roof nearing the end of its lifespan (15–80 years, depending on material) might need replacement to safely support panels.

Structural Integrity

Roofs with structural damage from settling foundations, wind, or leaks may not support additional weight without reinforcement. A structural engineer can assess this during an installer’s inspection. Additionally, the mounting equipment used in solar panel installations contributes to the overall weight of the system, which must be considered.

Roof Type

Pitched roofs distribute weight differently than flat roofs. Flat roof installations may require ballast (e.g., concrete slabs) to secure panels against wind, increasing the load to about 2.3 kg per square metre compared to 1.3 kg per square metre on slanted roofs.

Snow Load Considerations

In regions with heavy snowfall, solar panels are rated to withstand significant pressure, typically 5,000 Pascals (Pa), equivalent to 2–4 feet of snow. Installers account for local snowfall averages to ensure the system and roof can handle these loads.

A professional installer will conduct a structural assessment to confirm your roof’s suitability.

In most cases, modern roofs require no modifications, but older or compromised roofs may need reinforcement, which could add to installation costs.

Most domestic roofs can easily support the weight of a standard solar panel system, but it is essential to have a professional installer assess the roof’s capacity during their initial inspection.

How Many Solar Panels Does a Typical Home Need?

The number of solar panels depends on your household’s energy consumption, roof space, and panel wattage.

A typical UK three-bedroom home consumes around 2,700 kWh annually and requires 8–13 panels (350 W each) for a 3.5–4 kW system.

Larger homes with 4–5 bedrooms may need 13–16 panels, while smaller 1–2 bedroom homes might need 4–8 panels. Higher efficiency panels can lead to the need for fewer panels to meet energy requirements.

Each panel occupies about 2 square metres, so a 10-panel system requires approximately 20 square metres of roof space. When planning for solar panel installations, it is crucial to calculate how much roof space is required based on the number and dimensions of the panels.

Complex roofs with obstructions (e.g., chimneys, skylights) or limited south-facing areas may restrict the number of panels you can install.

The weight implication is straightforward: more panels mean more weight. For instance, a 13-panel system could weigh 234–273 kg (excluding mounting hardware), so ensuring your roof can handle this load is essential. Additionally, it is important to ensure the system generates enough power for the household’s energy needs.

Will Solar Panels Damage Your Roof?

When installed correctly by a professional, solar panels should not damage your roof. Key considerations include:

• Proper Installation – Panels are secured with mounting systems that distribute weight evenly. On pitched roofs, brackets are fixed to rafters, while flat roofs may use weighted ballasts to avoid drilling. Ensuring the roof remains watertight during installation is critical.
• Roof Condition – A roof in good condition is less likely to suffer damage. If repairs are needed, addressing them before installation prevents issues like leaks or weakened supports.
• Warranty Considerations – For flat roof installations, water pooling can degrade the silicon sealant between the panel’s frame and glass, potentially voiding warranties. Angling panels at 20–50 degrees (optimal for UK sunlight) mitigates this risk.

Professional installers follow UK building regulations, ensuring panels don’t extend more than 200 mm beyond the roof edge and are positioned to minimize structural stress.

What If Your Roof Can’t Support Standard Solar Panels?

If your roof is too weak or small, several alternatives exist:

Lightweight Panels

Options like Panasonic’s HIT N340 (below 22.4 kg) or thin-film solar panels are ideal for fragile or older roofs. Thin-film panels are flexible and can be installed on surfaces like garage roofs, caravans, or boats, requiring less structural support. Additionally, a solar panel array can be an efficient alternative when roofs cannot support the weight of a traditional setup.

Ground-Mounted Systems

If roof strength or space is an issue, ground-mounted systems are a viable alternative. Panels can be installed on the ground, provided you have sufficient land and optimal sunlight exposure.

Smaller Arrays

Compact panels, such as Sharp’s 258.4 W NQ-R Series (1.29 square metres), suit smaller roofs but may require more connections, increasing costs.

Garage Roof Installation

A medium single garage roof (2.7 m x 5.5 m) can support 4–6 panels, adding 60–120 kg plus mounting hardware. Installing solar panels on a garage roof is a viable option if your main roof is not suitable.

Additional Weight-Related Considerations

Mounting hardware

adds 15–20 kg per square metre to the total load. For flat roofs, ballasts like concrete slabs or weighted tubs increase this further to resist wind uplift.

The weight of solar panels on roof structures is determined by multiple factors, including the type of mounting system, the number of panels, and the materials used.

With the mounting equipment, it’s crucial to consider the weight when determining if a roof can support a solar panel installation. Alternatives are available if roofs cannot accommodate the weight.

Wind and Weather

High winds can exert uplift forces, requiring secure mounting. Installers design systems to withstand local wind conditions, sometimes adding extra weight for stability.

Structural Engineer Assessment

If there’s any doubt about your roof’s capacity, a structural engineer’s evaluation (often included in the installer’s inspection) ensures safety. This is especially important for flat roofs or garages requiring ballast.

Next Steps for Installing Solar Panels

Before installing solar panels, consult a professional installer like us here at Green Central to assess your roof’s structural integrity, orientation, and suitability. Most UK roofs can support solar panels without issue, but older or damaged roofs may need reinforcement. To get started:

1. Request Quotes: Use our online calculator to connect with trusted installers who can provide bespoke quotes and structural assessments.
2. Check Roof Condition: Ensure your roof is in good repair and structurally sound. A professional can advise on any necessary upgrades.
3. Consider Alternatives: If your roof isn’t suitable, explore lightweight panels, ground-mounted systems, or garage installations.

Solar panels are a long-term investment, offering average annual savings of £454 for a 3.5 kW system and a potential profit of £4,335 over 25 years. With proper installation, they pose minimal risk to your roof while significantly reducing your energy bills and carbon footprint.

For more information or to find installers use our quick quote tool to compare prices.