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PV panel installation on metal roofs – Weight limitations

Sustainable technologies – including solar PV systems – are playing important roles in helping to produce low carbon and energy efficient buildings. Tenants and landlords see the benefits, with Power Purchase Agreements (PPA) providing economic incentives to both.

Commercial Solar PV Installation

While investing in a solar PV system may seem like a straightforward decision for sustainability, careful planning must be taken into account for the condition of the metal roof. Before installation, a roof assessment should be conducted to determine the structural integrity and remaining life span of the roof.

The ideal scenario is for the life span of the roof to align with the estimated 25 year life cycle of the PV system.

If the roof has a shorter life span, it is recommended to replace or refurbish it prior to installing the PV panels, to avoid future complications.

Weight Matters

According to Part A of the Building Regulations, if the weight increase is significant (over 15%), a structural survey is required to determine if strengthening work is needed. The structural integrity of the roof must be considered when planning the installation of a PV system, including the extra weight that the panels will bring.

The results of the survey will determine if the roof is suitable to safely hold the panels and if replacing or refurbishing the roof is necessary.

The average commercial solar panel weighs 22kg, meaning that for a 2,000m2 building, there will be an additional 22 tonnes of weight.

The fixing method must also be taken into account, as a ballasted system, for example, will bring additional weight to anchor the array to the roof.

Replace, Repair, or Refurbish?

Replacing the roof is the best way to ensure that it is structurally sound for the extra weight from the PV system, but it is not the most sustainable option. The cost, complexity, and disruption of a new roof, along with the carbon footprint from the extraction and transportation of the new metal, must be taken into account. Repairs may be a cost saving option, but they do not resolve all roof issues and may end up being a waste of time and money.

Refurbishing the roof by oversheeting, placing new metal sheets over the existing roof, is another option. This will add significant weight to the roof, for example, the 2,000m2 roof will gain approximately an additional 30 tonnes.

Sharmans Roof Refurbishment Systems: The Solution

Sharmans market leading metal roof coating systems, Delcote® and Seamsil®, refurbish the existing roof to extend its life cycle, whilst offering a product guarantee of up to 25 years, aligning with the PV system’s life span.

These systems offer a lightweight refurbishment solution, only taking into account the additional weight of the PV system and its components when considering structural loading.

If a structural survey determines that roof refurbishment is the best option, businesses should choose Sharmans roof refurbishment systems.