Photovoltaics on a corrugated industrial roof. Load paths and maintenance access

Access may be much harder once the modules are in place. Establish what an older roof covering is made of if its composition is uncertain. Instructions for modern asbestos-free sheets cannot establish whether it is safe to drill into an unidentified roof during the survey.

If the project includes replacing the covering, an integrated solar roof is another option. Solar roofing manufacturers and brands include GAF Energy, Terrán, ML System, Electrotile, Wienerberger Wevolt, MDM NT (MyRoof), SunRoof, Tesla, SolRoof and LUMA Solar.

The mounting structure must carry the array’s weight and transmit wind and snow loads to the building structure through the specified connections. Asbestos-free fibre-cement sheets cannot serve as the sole support for a module frame. Avoid unintended pressure on the sheets or a support bearing on a sheet between purlins. Have the designer check the fasteners, purlins, primary structure and connections against the actual conditions, particularly on older buildings where the drawings may be out of date. A roof’s ability to carry past snow loads does not establish spare capacity for the array.

At each fixing, check the corrugation geometry, support position and seal. Details for sheet metal or another board profile cannot simply be transferred to fibre cement. The hole must suit the fixing and allow the movement specified for the joint. Take clearances and spacing from the selected system’s documentation. Excessive compression can damage the sheet, while insufficient compression can let water past the seal. Specify the fixing and sealing set before work starts. Substituting a washer or fastener can affect the performance of the entire penetration.

Lay out the array so that water can run off and accumulated leaves and dirt can be removed. Eaves and ridge details must remain functional, including ventilation openings at the ridge or elsewhere. Leave critical joints in the fibre-cement covering accessible for inspection. Consider where debris will collect beneath frames and how maintenance staff will reach it. Once the array covers areas previously visible from a distance, the roof inspection plan may need more specific access and inspection points.

Provide a safe route to the equipment and its connections for both routine inspections and roof repairs. Do not expect technicians to walk directly on the sheets. Fibre cement is sensitive to concentrated loads, and reinforcing strips cannot replace walkways and fall protection. Work out how to replace a damaged sheet beneath the array. If several modules would have to come off, establish the cost and sequence of work before approving the final layout.

Route and secure cables and equipment according to the electrical design. Loose cables in the troughs can damage the roof surface or interfere with runoff. Assess electrical and fire safety for the complete installation. The sheet’s reaction-to-fire class describes only the product. Coordinate the roofing and photovoltaic contractors, then inspect areas that carried loads during installation. Later trades can damage a roof that was sound when the roofers handed it over.

Give the owner drawings showing fixings, supports, penetrations and access routes. Mark the fibre-cement sheets under the panels and record the profile designation. Agree who is responsible for seals and how leaks will be investigated. Include the connections, corrosion of metal parts and clear drainage routes in routine inspections alongside the modules. High winds or other exceptional events may warrant a wider inspection. A coherent set of records helps locate a fault in the equipment, bracket or roof covering before parts are replaced.

Before ordering the array, confirm the roof’s condition, the load path and the fixing detail. Allow for safe maintenance and future repairs to the roof covering in the same design.