TecTopics: Recommendations for Roof Mounted Solar Panel Installations
Low-slope rooftops provide excellent opportunities for photovoltaic (PV) installations due to their relatively flat, unused space that is often out of sight. Consequently, there is a growing demand for roof-mounted PV systems to enhance sustainability by reducing energy consumption while generating a tangible return on investment (ROI). However, amidst the growing demand and the fast-paced nature of the PV industry, it’s crucial not to overlook the roof system itself. Key considerations regarding the roof system include:
Here are some design recommendations to ensure that the roof and PV system work harmoniously for optimal performance.
Warranty Consultation: PV installations can significantly affect roof warranties. Therefore, it is advisable to consult with the roofing manufacturer before proceeding with the PV installation. This ensures that the installation does not interfere with the issuance of a new warranty or alter the terms of any existing warranties.
Pre-Installation Inspection: For installations over an existing warrantied roof, notify the manufacturer and arrange for a Field Service Representative to conduct a thorough inspection before solar installation. Any necessary repairs or upgrades should be completed and reinspected prior to the PV system installation.
Protect Heavy Traffic Areas: Protect areas heavily traveled during PV array installation and maintenance with walkway pads and/or pavers.
Rack-Supported PV Arrays: Use rack-supported PV arrays that provide proper clearance to access the roof membrane for future inspections and repairs.
Mechanically Fastened Solar Mounts: Consider using mechanically fastened solar mounts with elevated stanchions and racking. These mounts offer a more secure installation, greater access to the membrane for future maintenance, inspection, and repairs, and do not impede drainage. Carlisle recommends the use of the following mechanically fastened solar anchors and will include the flashing in the Total System Warranty:
- Solar Skyrack Mounts
- Anchor Products U-Anchor 1400
- Anchor Products U-Anchor 2400
- OMG PowerGrip Plus
- OMG PowerGrip Universal 7 with CCM Flashing Disc (provided by OMG)
Ballasted PV Systems: If choosing a ballasted PV system, install a protection layer such as Carlisle’s Pressure-Sensitive Molded Walkway Pads or similar under the racking. Choose ballast blocks suitable for roof applications that perform for the system's life.
Sacrificial Sheets for PV Laminates: If PV laminates are chosen, they should not be adhered directly to the primary roof membrane. Instead, use a sacrificial sheet.
Non-Penetrating Attachment Methods: Using only adhesive or heat welding for attaching systems directly to Carlisle membranes is not recommended. Depending solely on the roof membrane to secure the PV system can lead to premature failure of the roof.
Sufficient Clearance for Maintenance: Ensure that solar panels provide sufficient clearance around all roof areas, including mechanical units and drains, to allow for necessary maintenance and future repairs.
Post-Installation Inspection: Following the solar panel installation, have the roof reinspected by a Field Service Representative to check for any damage and ensure proper installation of any new details.
Additional Recommendations for Existing Roofs (More Than One Year After Warranty Issuance)
Consider Installing a New Roof: Installing a new roof that lasts as long or longer than the expected service life of the solar array is usually the most prudent decision. Installing solar panels on an older roof is not recommended, as it will likely need to be replaced before the PV system.
Additional Recommendations for New Roofs
Use Thicker Membranes: Utilize thicker membranes such as 80-mil and 90-mil materials or FleeceBACK® membrane for a more durable, longer-lasting roof system. Consider PVC material and gypsum cover boards for enhanced fire resistance.
Rigid Cover Board Installation: Attach a rigid cover board with urethane adhesive.
Reflective Membrane for Bi-Facial Panels: If installing bi-facial solar panels, use a highly reflective white TPO or PVC membrane.
For more information on Carlisle’s Solar Ready Roof Recommendations, visit the links below:
Rooftop Solar Installation Guide
PV Letter of Compliance
Solar Ready Roof Brochure
- Expected service life of the roof versus the solar array.
- Roof warranties and the ability to access the membrane for future repairs.
- Roof reflectivity and fire resistance.
- Roof access, increased foot traffic, and maintenance requirements.
- Solar panel attachment and racking system.
Here are some design recommendations to ensure that the roof and PV system work harmoniously for optimal performance.
Warranty Consultation: PV installations can significantly affect roof warranties. Therefore, it is advisable to consult with the roofing manufacturer before proceeding with the PV installation. This ensures that the installation does not interfere with the issuance of a new warranty or alter the terms of any existing warranties.
Pre-Installation Inspection: For installations over an existing warrantied roof, notify the manufacturer and arrange for a Field Service Representative to conduct a thorough inspection before solar installation. Any necessary repairs or upgrades should be completed and reinspected prior to the PV system installation.
Protect Heavy Traffic Areas: Protect areas heavily traveled during PV array installation and maintenance with walkway pads and/or pavers.
Rack-Supported PV Arrays: Use rack-supported PV arrays that provide proper clearance to access the roof membrane for future inspections and repairs.
Mechanically Fastened Solar Mounts: Consider using mechanically fastened solar mounts with elevated stanchions and racking. These mounts offer a more secure installation, greater access to the membrane for future maintenance, inspection, and repairs, and do not impede drainage. Carlisle recommends the use of the following mechanically fastened solar anchors and will include the flashing in the Total System Warranty:
- Solar Skyrack Mounts
- Anchor Products U-Anchor 1400
- Anchor Products U-Anchor 2400
- OMG PowerGrip Plus
- OMG PowerGrip Universal 7 with CCM Flashing Disc (provided by OMG)
Ballasted PV Systems: If choosing a ballasted PV system, install a protection layer such as Carlisle’s Pressure-Sensitive Molded Walkway Pads or similar under the racking. Choose ballast blocks suitable for roof applications that perform for the system's life.
Sacrificial Sheets for PV Laminates: If PV laminates are chosen, they should not be adhered directly to the primary roof membrane. Instead, use a sacrificial sheet.
Non-Penetrating Attachment Methods: Using only adhesive or heat welding for attaching systems directly to Carlisle membranes is not recommended. Depending solely on the roof membrane to secure the PV system can lead to premature failure of the roof.
Sufficient Clearance for Maintenance: Ensure that solar panels provide sufficient clearance around all roof areas, including mechanical units and drains, to allow for necessary maintenance and future repairs.
Post-Installation Inspection: Following the solar panel installation, have the roof reinspected by a Field Service Representative to check for any damage and ensure proper installation of any new details.
Additional Recommendations for Existing Roofs (More Than One Year After Warranty Issuance)
Consider Installing a New Roof: Installing a new roof that lasts as long or longer than the expected service life of the solar array is usually the most prudent decision. Installing solar panels on an older roof is not recommended, as it will likely need to be replaced before the PV system.
Additional Recommendations for New Roofs
Use Thicker Membranes: Utilize thicker membranes such as 80-mil and 90-mil materials or FleeceBACK® membrane for a more durable, longer-lasting roof system. Consider PVC material and gypsum cover boards for enhanced fire resistance.
Rigid Cover Board Installation: Attach a rigid cover board with urethane adhesive.
Reflective Membrane for Bi-Facial Panels: If installing bi-facial solar panels, use a highly reflective white TPO or PVC membrane.
For more information on Carlisle’s Solar Ready Roof Recommendations, visit the links below:
Rooftop Solar Installation Guide
PV Letter of Compliance
Solar Ready Roof Brochure
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