Commercial Solar Structural Assessment & Engineering
Professional structural engineering for commercial rooftop solar panels
A commercial rooftop solar installation must work with the building that supports it
Solar panels, mounting systems and, where applicable, ballast introduce additional loads to the roof and supporting structure. Before a commercial solar PV system is installed, those loads need to be properly understood and the suitability of the existing structure considered.
At Green Squirrel, structural assessment forms an important part of our professional commercial solar PV design process.
We coordinate structural engineering alongside the solar design so that panel layouts, mounting arrangements and proposed loads can be assessed against the actual building rather than treating structural suitability as an afterthought.
We also offer our commercial solar structural assessment service independently to other companies, including solar PV installers, developers, consultants, roofing contractors, property professionals and building owners who require professional structural input for their own solar projects.
Our service can range from an initial structural feasibility desk study through to site inspection, detailed structural analysis and strengthening proposals where required.
Structural Assessment for Commercial Solar PV
Commercial roofs vary considerably in construction, age, condition and structural capacity. Two buildings that appear similar externally may have very different capabilities when additional rooftop loading is considered.
A structural assessment can consider the effects of the proposed solar installation on elements including:
- Roof construction
- Steel portal frames
- Columns
- Structural connections
- Proposed solar PV loading
- Ballast loading where applicable
- Snow loading
- Previous structural alterations
- Rafters and beams
- Purlins
- Bracing systems
- Existing roof loading
- Mounting-system loads
- Wind loading
- Existing strengthening
- Over-roofing and over-cladding
The appropriate level of assessment depends on the building, proposed PV system and quality of the structural information available. Not every project requires a full structural analysis.
Our objective is to establish a proportionate engineering approach for the individual building.
Part of Our In-House Commercial Solar Design Process
For Green Squirrel commercial solar projects, structural considerations can be incorporated directly into the PV design process. This is important because solar and structural design should not be treated as completely separate exercises. The proposed panel arrangement affects the loads being applied to the building, while the structural characteristics of the building may influence where panels can be positioned and which mounting arrangement is appropriate.
By considering the two together, we can coordinate information such as:
- Proposed solar panel layout
- Mounting-system information
- Ballast requirements where applicable
- Structural frame arrangement
- Potential loading constraints
- Module specifications
- Panel and mounting-system dead load
- Roof zones
- Existing roof construction
If structural limitations are identified, the solar design can potentially be adapted before the project reaches installation. This can help avoid situations where a solar PV system has been fully designed only for structural concerns to emerge later.
Structural Engineering Services for Solar Installers and Other Companies
Our structural assessment service is not limited to Green Squirrel solar installations. We can also provide structural engineering support for commercial solar PV projects designed or installed by other organisations.
This may be particularly useful for:
- Commercial solar PV installers
- Renewable-energy contractors
- EPC contractors
- Property consultants
- Architects and building consultants
- Property owners
- Electrical contractors
- Solar developers
- Roofing companies
- Facilities-management companies
- Commercial landlords
- Asset managers
You can provide us with your proposed PV layout and relevant mounting information, together with any available structural drawings or building information. We can then establish the appropriate level of structural assessment for the project.
This allows solar contractors and other professionals to access structural engineering support without needing Green Squirrel to undertake the complete solar installation.
Portal-Frame Buildings and Commercial Solar
Steel portal-frame buildings are common across industrial estates, warehouses, manufacturing facilities and agricultural premises. They are also among the most common building types considered for large commercial rooftop solar installations.
A structural assessment may need to consider not only the main portal frame but also:
- Secondary steelwork
- Rafters
- Haunches
- Bracing
- Existing modifications
- Columns
- Purlins
- Connections
Older portal-frame buildings can require particular care because their original design assumptions, structural information and subsequent alterations may differ considerably.
Where reliable structural information is available, specialist structural analysis can be used to investigate the effect of the proposed PV installation.
Our Commercial Solar Structural Assessment Process
Not every building requires the same level of structural investigation. A relatively modern building with comprehensive structural drawings may be capable of being assessed principally from existing information. An older, modified or poorly documented building may require considerably more investigation.
The assessment can therefore progress through a number of stages.
1. Structural Feasibility Desk Study
The first stage is often a desktop structural feasibility assessment. We review the proposed solar PV system alongside the structural information available for the building.
Information considered can include:
- Proposed solar PV layout
- Panel specifications
- Mounting-system details
- Panel and mounting-system weight
- Ballast calculations where applicable
- Roof construction
- Structural frame type
- Building dimensions
- Original structural drawings
- As-built information
- Structural calculations where available
- Building age
- Original design information
- Previous extensions or alterations
- Roof replacement
- Over-roofing or over-cladding
- Existing rooftop plant
Where sufficient reliable information is available, a desk study may be capable of establishing whether the proposed solar PV loading can be accommodated or whether additional investigation is required.
The outcome may also identify particular areas of the roof or structure requiring further consideration.
2. Structural Site Inspection
Where structural drawings are unavailable, incomplete or need verification, a site inspection may be recommended.
A structural engineer may need to inspect elements such as:
- Main structural frames
- Portal-frame rafters
- Roof beams
- Purlins
- Columns
- Bracing
- Structural connections
- Existing strengthening
- Previous structural alterations
- Roof construction
The purpose of the inspection is to obtain additional information about the building as it actually exists.
This can be particularly important on older buildings or properties that have undergone alterations since their original construction.
Some projects may require access equipment, opening-up works or assistance from roofing or building contractors to expose structural elements.
Where this is necessary, the required access can be identified before the inspection.
3. Detailed Structural Assessment
Where a feasibility assessment alone cannot demonstrate sufficient structural capacity, more detailed engineering analysis may be required.
The scope depends on the building and proposed solar installation but can include assessment of:
- Steel portal frames
- Rafters and roof beams
- Purlins
- Columns
- Bracing systems
- Connections
- Secondary steelwork
- Foundations where relevant
- Existing permanent loads
- Additional permanent solar PV loads
- Wind actions
- Snow loading
The proposed PV system can then be considered in relation to the existing structure.
The objective is to determine whether the building is suitable for the proposed installation and identify any structural constraints that need to be addressed.
4. Structural Strengthening Design
A building that cannot accommodate the proposed solar PV loads in its existing condition does not necessarily have to be ruled out. In some circumstances, relatively targeted strengthening can enable the project to proceed.
Depending on the structural issue identified, potential strengthening measures may include:
- Additional structural steelwork
- Strengthening of rafters or beams
- Additional purlins
- Additional bracing
- Strengthened connections
- Secondary steelwork
- Load redistribution
- Localised strengthening
- Alterations to the proposed PV layout
Where strengthening is appropriate, structural engineering proposals can be developed for the required works.
The solar design can then be coordinated with the structural solution.
Solar PV Loading Is More Than Panel Weight
One of the reasons professional structural assessment is important is that the structural implications of rooftop solar cannot always be determined simply by looking at the weight of an individual panel. The complete installation can introduce or influence a number of loading considerations.
These may include:
Permanent load
The weight of the panels, mounting system, ballast and associated equipment.
Wind actions
Solar arrays and mounting systems are exposed to wind forces that vary depending on building height, location, roof geometry and the position of the array on the roof.
Snow loading
The presence and arrangement of rooftop solar panels can influence snow distribution and accumulation.
Existing roof loads
The roof may already support plant, services, over-cladding or other permanent loads.
Existing structural capacity
The original building may have limited spare capacity, or previous modifications may have changed its structural behaviour.
For this reason, simply confirming the total weight of a solar array does not necessarily establish whether a commercial roof is suitable.
Over-Roofing and Previous Building Alterations
One issue that can easily be overlooked when assessing an existing commercial roof is previous alteration.
For example, a building may originally have had spare structural capacity, but subsequent over-roofing or over-cladding may already have consumed some of that allowance.
Other changes can include:
- Additional roofing systems
- HVAC equipment
- Roof-mounted plant
- Removed or modified bracing
- Suspended services
- Roof-mounted plant
- Structural alterations
- Changes in building use
Structural suitability should therefore be based on the building in its current configuration rather than simply assuming that its original design capacity remains available
Agricultural and Older Commercial Buildings
Older industrial and agricultural buildings can present particular structural considerations. Some may have limited original design information.
Others may have been designed to standards, loading assumptions or construction practices different from those used today. Agricultural buildings may also have changed use during their life.
Where an older agricultural structure has subsequently become a commercial or industrial building, additional investigation may therefore be appropriate before installing a substantial rooftop solar PV system. The correct approach depends on the individual structure and the information available.
Structural Engineering Can Influence the Solar Design
Structural assessment is not simply a pass-or-fail exercise.
The findings can sometimes be used to refine the solar PV design.
For example, engineering assessment may identify:
- Areas of greater structural capacity
- Areas where panel loading should be reduced
- Locations where ballast should be limited
- Sections requiring strengthening
- Alternative mounting arrangements
- Opportunities to redistribute loads
- Areas of the roof that should remain clea
This is one of the advantages of considering structural engineering during the design process rather than only immediately before installation.
The PV layout and structural assessment can inform one another.
What Information Do We Need?
To start a commercial solar structural assessment, we normally request as much relevant information as is available.
Solar PV Information
This can include:
- Proposed solar PV layout
- Number of modules
- Panel manufacturer and model
- Panel dimensions and weight
- Mounting-system specification
- Mounting-system weight
- Ballast calculations where applicable
- Proposed inverter or equipment locations
- Any known loading information
Building Information
Useful building information can include:
- Property address
- Building dimensions
- Building age
- Building use
- Roof construction
- Structural frame type
- Original structural drawings
- As-built drawings
- Existing structural calculations
- Details of extensions
- Previous structural alterations
- Over-roofing or roof replacement information
- Details of existing rooftop equipment
Do not be concerned if all of this information is unavailable. We can review what you have and establish whether further information, investigation or a site inspection is required.
Why Use Green Squirrel for Solar Structural Assessments?
Commercial solar structural engineering sits directly alongside our wider expertise in solar PV design. That means we understand that the structural assessment is not an isolated engineering exercise — it forms part of the successful design and delivery of the complete solar project.
Our approach is based around:
Solar-specific understanding
We understand the information required to assess commercial rooftop PV installations and how structural findings can affect system design.
Engineering-led assessment
We take a proportionate approach based on the building, available information and proposed installation.
Coordination with PV design
For our own installations, structural considerations form part of the wider commercial solar design process.
Independent structural support
We can also provide the service for solar PV systems being designed and installed by other companies.
Clear progression
Where a desk study is insufficient, the assessment can progress to inspection, detailed analysis and strengthening design where appropriate.
Practical solutions
Where structural constraints are identified, the objective is to understand whether the design can be adapted or strengthening can provide a practical route forward.
Structural Assessment for Your Own Solar PV Project
If Green Squirrel is designing your commercial solar PV installation, we can incorporate the structural assessment into the wider design and feasibility process. This allows the solar layout, mounting system and structural considerations to be coordinated as the project develops.
Our objective is to identify significant structural issues before installation and ensure that the proposed design is supported by an appropriate level of engineering assessment.
Structural Assessment for Solar Installers, Contractors and Developers
Already have your own solar design? We can provide the structural engineering assessment independently.
Send us the proposed PV layout, panel and mounting-system information together with any available drawings or structural information for the property.
We can review the project and establish the appropriate scope, from an initial feasibility desk study through to detailed assessment where required.
This service can support individual commercial installations as well as solar contractors requiring structural engineering input across multiple projects.
Request a Commercial Solar Structural Assessment
Whether you are a building owner considering commercial solar or a solar company requiring structural engineering support for a client project, Green Squirrel can help establish the structural feasibility of the proposed installation.
- Any available roof or structural drawings
- The property address
- Panel specifications
- Details of known alterations or over-roofing
- Proposed solar PV layout
- Mounting-system information
We can then review the available information and advise on the appropriate next stage.
