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CROSS Safety Report

Loading from solar panels

Report ID: 280 Published: 1 January 2012 Region: CROSS-UK

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Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.


A reporter inspected a roof to discover that the structure was already overloaded with the self weight of the roof covering without the addition of solar panels.

Key Learning Outcomes

For solar panel suppliers, installers, and homeowners:

  • All roofs should be appraised by a competent and suitably qualified engineer for the suitability of accommodating solar panels

  • Inspection by a competent person should be carried out to ensure the works are installed in accordance with the design intent

For civil and structural design engineers:

  • Load effects of snow and wind uplift acting on the roof structure due to solar panels should be carefully considered, particularly for sliding snow

Full Report

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This section contains the Full Report submitted to CROSS and describes the reporter’s concerns or experiences. However, the text has been edited for clarity, and identifiable details have been removed to ensure anonymity and confidentiality. If you would like to know more about our secure reporting process, or submit a report yourself, please visit the reporting to CROSS-UK page.


Another reporter visited a dwelling which already had a two solar panels installed on the roof and where the owner then wished to have more. The reporter inspected the roof framework and advised the panel supplier that the structure was already overloaded with the self weight of the roof covering without the addition of solar panels.

The property was built in 1971 and has a very slim roof structure which, in the opinion of the reporter, would be in danger of collapse if a snow load of any significance were to be added to the loading of the weight of any solar panels on an already overstressed structure. 

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

The installation of solar PV panels is a material alteration under the building regulations and needs assessment. In England this is to be done either under a competent persons scheme (such as the MCS scheme) or the local authority requires notification. Some competent person’s schemes only operate for electrical requirements of the regulations and then need the local authority to check other relevant aspects such as Parts A and C of the building regulations.

Roof loads

Issues of loading on existing roofs whether wind or snow or dead therefore come under control. Clearly there is a need to assess whether an existing roof structure can carry the extra load and that applies globally and locally (at fixing points). But there are additional concerns.

In the past CROSS has reported on many cases of danger following parts becoming detached from roofs. It is essential that panels are properly fixed down against the very high suction loads that might occur. In areas of higher snow load sudden thaws can cause snow slides with significant impact and danger if the slides fall on people or adjacent lower lying roofs.

It is essential that panels are properly fixed down against the very high suction loads that might occur

Are concerns likely to increase?

The potential for large slides might exist given the nature of panel surface material. The concerns are likely to increase as pressure to reduce energy consumption grows. Insufficient attention being paid to structural integrity is not new on small works. The examples quoted above all relate to competence and so far, the solar panel industry is unregulated.

Notwithstanding this the installation of solar panels is covered by the CDM Regulations and hence all those involved have statutory duties to safeguard others. It may be that a code of practice could be a good starting point. The Scottish Government has published a report: Risk assessment of structural impacts on buildings of solar hot water collectors and photovoltaic tiles and panel – final report.

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