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LEARNING HUB
Installation
Sequence
Understand the typical biosolar roof installation sequence from waterproofing and drainage through mounting, green roof build-up, solar PV installation, inspection and handover.
How a Biosolar Installation Works
A biosolar installation brings the roof, green roof and solar PV system together as one coordinated build-up.
The exact sequence varies between manufacturers and system types, but each stage should protect the waterproofing, preserve drainage and allow the mounting, planting and PV systems to be completed without conflict.
Good coordination helps create a stable, maintainable roof where every part of the biosolar system can perform properly over the long term.
Important: Always follow the selected manufacturer’s approved build-up, installation sequence and warranty requirements.
In Simple Terms:
Prepare the roof and set out the system
Start with a completed roof and confirm the mounting, drainage and access positions.
Build the mounting and green roof
Install the supporting components and complete the surrounding green roof build-up.
Complete the solar PV and planting
Fit the PV system, finish the vegetation and inspect the completed biosolar roof.
Important: Follow the approved manufacturer sequence for the selected system.
Installation Sequence at a Glance
01
Roof Ready
Waterproofing completed, inspected and ready to receive the specified biosolar build-up.
04
Complete the Green Roof
Drainage layers, substrate and planting areas completed around the mounting system.
02
Set Out
Mounting positions, drainage routes, access zones and roof constraints clearly established.
05
Install Solar PV
Modules, cabling and associated electrical equipment installed and tested.
03
Build the Support System
Mounting supports, rails and required structural components installed and aligned.
06
Inspect & Handover
The completed roof is checked, documented and prepared for ongoing maintenance.
Phase One
Prepare the Roof & Establish the Interfaces
This phase prepares the finished roof to receive the biosolar system and confirms where all key components will sit.
Prepare the Roof
Confirm the waterproofing is complete, signed off and ready to be covered. Clean the roof and protect the working area before installation begins.
Set Out the Layout
Transfer the approved design onto the roof and mark the mounting, drainage and access zones. Confirm positions against outlets, penetrations and roof edges.
Install Protection & Drainage Layers
Install the specified protection and drainage components in the correct sequence. These layers form the foundation for the green roof and mounting system above.
Key Point at This Stage
Protect the waterproofing, keep drainage routes clear and confirm the layout accurately before later layers make changes more difficult.
Phase Two
Build the Mounting & Green Roof System
This phase forms the structural and growing base of the biosolar roof and sets up the system for both stability and planting performance.
Install the Mounting Components
Position the support elements, rails and required structural components in line with the approved design. Check alignment, spacing and fixing points before continuing.
Complete the Green Roof Build-Up
Install the specified green roof layers around the mounting system. Maintain the correct sequence, build-up depths and clear drainage paths throughout the roof.
Confirm Stability Requirements
Where the design relies on ballast, substrate depth or specific distribution, these requirements must be fully achieved. The mounting system should not be treated as complete until this is confirmed.
Key Point at This Stage
The mounting system and green roof build-up must be completed together so stability, drainage and long-term performance are not compromised.
Phase Three
Complete Solar PV & Vegetation
This phase completes the active solar system, establishes the planting and prepares the finished roof for inspection and handover.
Install the Solar PV
Fit the PV modules onto the completed mounting system and secure them in line with the approved solar design. Complete cable routing and electrical works without obstructing access or drainage.
Complete the Planting
Install the specified vegetation in accordance with the green roof design. Planting should suit the light, shade and moisture conditions created by the PV layout.
Carry Out Final Inspection
Check that the completed roof meets the required standards for safety, drainage, access, planting and PV installation. Record any final information needed for handover and maintenance.
Key Point at This Stage
The completed roof should be treated as one coordinated biosolar system, not as separate roofing, green roof and solar packages.
Critical Hold Points
01
Waterproofing Complete
Before progressing: Confirm the membrane has been inspected, required testing completed and critical roof details accepted.
02
Before Interfaces Are Covered
Before progressing: Check mounting positions, lower components and drainage routes while they remain visible and accessible.
03
Before PV Modules Are Fitted
Before progressing: Confirm the mounting structure is complete, correctly aligned and ready to receive the modules.
04
Before Handover
Before progressing: Verify the completed PV, vegetation, drainage, access and safety requirements before final sign-off.
Who Is Responsible for What?
Responsibility varies between contracts and manufacturers, so these should be treated as typical roles rather than fixed rules.
Typically responsible for:
-
Waterproofing installation
-
Critical roof detailing
-
Relevant roof inspections
-
Waterproofing warranty requirements
Roofing Contractor
Typically responsible for:
-
Green roof build-up
-
Growing substrate
-
Vegetation installation
-
Establishment requirements
Green Roof Contractor
Typically responsible for:
-
PV mounting within their package
-
Solar PV modules
-
Electrical installation
-
PV testing and commissioning
Solar / Biosolar Installer
The Important Part:
Responsibility at the interfaces must be clearly agreed.
Mounting components, waterproofing, drainage, substrate levels and installation sequencing can involve more than one trade. Clear ownership should therefore be established before work starts rather than resolved on site.
Final Inspection & Handover
Physical Inspection
Project Information
Maintenance Handover
-
PV modules and mounting are complete
-
Vegetation and substrate are correctly distributed
-
Drainage outlets and routes remain accessible
-
Required fire and separation zones remain clear
-
Safe maintenance access has been retained
-
As-built drawings and layouts
-
PV testing and commissioning information
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Product information and warranties
-
Green roof maintenance requirements
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Inspection and handover records
-
The building owner or facilities team should receive coordinated maintenance information covering both the solar installation and green roof so the complete biosolar system can be managed safely over its service life.
WHERE TO GO NEXT
To understand how biosolar compares with other combined roof systems, continue to Biosolar vs Green Roof Solar.
If you’d like to explore what a biosolar roof can achieve in terms of energy performance, biodiversity value, and planning outcomes, visit Key Benefits.
For policy drivers and regulatory context, the Biosolar and Planning / Policy page provides a concise overview of current UK guidance.
If you’re seeking a specialist contractor to deliver a biosolar roof system visit PV Plus
