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INSTALLATION SEQUENCE
Integrated biosolar systems are designed so the solar mounting structure works in harmony with the green roof build-up. The green roof layers contribute to ballast, drainage, habitat creation and long-term system performance, while the PV components are installed without penetrating the waterproofing. The sequence below outlines how these systems are typically installed on UK projects in line with recognised best practice.
PREPARE THE ROOF AND INSTALL PROTECTION & DRAINAGE LAYERS
After the waterproofing has been fully signed off, the roof is cleaned and the layout grid is marked.
Protection layers and drainage components are installed first, forming the foundation for both the green roof and the biosolar mounting system.
Base plates and anchor boards are positioned according to the project layout. Their alignment is critical as these zones determine the final placement of the mounting frames.
Considerations:
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Ensure safe access to roof levels before works begin.
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Check all edges, upstands and penetrations for compliance with fall-protection requirements.
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Confirm waterproofing is undamaged before proceeding to the next stage.
LAY THE FILTER FLEECE ACROSS VEGETATED AREAS
A filter fleece is rolled out across all areas that will receive substrate.
It is lapped, neatly cut around mounting points and weighted temporarily to prevent movement.
The fleece prevents fines from entering the drainage layer and is a key component of green roof performance.
Considerations:
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Avoid creating wrinkles or folds that may trap water.
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Maintain fire breaks in line with RC62 recommendations (no fleece or substrate should bridge designated breaks).
INSERT MOUNTING SUPPORTS INTO THE BASE PLATE
Angled supports (or similar load-distributing components) are inserted into pre-designated openings within the anchor layer and secured into the base plate, according to the layout plan.
This stage establishes the structural alignment of the PV array.
Because integrated systems avoid roof penetrations, stability depends on:
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Correct positioning of supports
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Proper connection to the base plates
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Adequate ballast applied later through substrate
Considerations:
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Do not load or lean on the frames before ballast/substrate is installed.
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Ensure spacing allows for safe future access routes.
FIX THE MODULE CARRIER RAILS AND STRUCTUAL BRACING
Carrier rails are fitted to the supports and aligned across the array.
Diagonal bracing is added where required to resist lateral forces and wind uplift.
Longer runs may require connector sections to create continuous rails.
Considerations:
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All fixings must be tightened to the recommended torque values.
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Rails must be level to avoid stress on modules.
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Ensure no components obstruct fire breaks or drainage paths.
APPLY SUBSTRATE AROUND THE BENEATH THE MOUNTING SYSTEM
Substrate is placed around the mounting structure to the project-specific depth determined by wind load and ballast calculations.
In an integrated biosolar system, substrate is a critical ballast component. It provides the stabilising force that prevents uplift during high winds. For this reason:
PV modules must not be installed until the full ballast/substrate depth is achieved and verified. Uneven or insufficient substrate can compromise the structural stability of the system.
Considerations:
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Maintain drainage routes and avoid blocking outlets.
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Maintain RC62-compliant firebreaks.
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Keep substrate clear of clamps, mechanical fixings and cable pathways.
INSTALL PV MODULES AND COMPLETE ELECTRICAL WORKS
Once ballast is confirmed, PV modules are placed onto the carrier rails and secured with module clamps.
Clamps must be tightened using the correct torque for the specific module type.
Electrical installation follows national standards (e.g., BS 7671) and should occur without compressing vegetation or restricting plant growth beneath the array.
Considerations:
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Never install modules before ballast is in place.
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Avoid stepping on rails or supports once modules are mounted.
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Keep DC cabling tidy and elevated to avoid contact with moist substrate.
PLANTING AND VEGETATION INSTALLATION
Vegetation is installed last.
Different planting mixes may be used beneath panels compared with open areas, allowing species suited to shaded or semi-shaded conditions to establish.
Temporary irrigation may be needed during establishment.
Considerations:
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Do not disturb electrical cables while planting.
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Maintain clear perimeter and internal firebreak zones.
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Ensure vegetation does not obstruct access routes or module edges.
FINAL CHECKS, COMMISSIONING & HANDOVER
A final inspection confirms:
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PV alignment, fixings and torque settings
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Vegetation coverage and substrate distribution
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Compliance with drainage, access and firebreak requirements
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Safe cable routing and isolation points
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Clear access for ongoing maintenance
A coordinated maintenance plan covering both the solar installation and the green roof should be implemented to ensure long-term performance of the complete biosolar system.
INSTALLATION RESPONSIBILITIES: SPLIT VS SPECIALIST CONTRACTORS
On many projects:
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Roofing contractors install the anchor boards, protection layers, drainage components and the biosolar mounting supports.
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Solar contractors mount the PV modules and complete electrical works.
While possible, this can create split responsibility for ballast, alignment, stability and interface details — areas where errors are difficult and costly to correct.
Specialist biosolar installers, such as PV Plus, resolve this issue.
A specialist team can:
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Install the anchor boards and mounting system with full knowledge of requirements
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Coordinate with green roof contractors to ensure correct substrate depths
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Maintain clean accountability for stability and performance
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Reduce sequencing issues between trades
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Ensure warranties are not compromised by ambiguous responsibility
This approach typically results in a more reliable, accurate installation and simplifies future maintenance.
WHERE TO GO NEXT
To understand practical site needs, coordination risks and common mistakes to avoid, continue to Site Requirements & Common Issues.
For long-term roof performance and system care, visit Biosolar Maintenance Overview.
For design-stage parameter ranges and guidance on spacing, clearances and loads, see the BSH Design Parameters Summary in the Downloads section.
If you’re seeking a specialist contractor to deliver a biosolar roof system visit PV Plus
