For facilities managers concerned with sustainability and rising energy prices, the benefits of installing solar panels or Photovoltaic arrays onto the roofs of their buildings are clear to see. But is the process as straightforward as you might think?
18 August 2015 | By Andrew Brewster
Whether the concern relates to restrictions, in terms of health and safety, or how the technology will impact the roofing system beneath and its associated guarantees, there are a number of issues which FMs need to be aware of when considering this technology.
The safety of every operative or site visitor has to be the number one priority for any facilities manager and at no time is this more critical than when managing the risks associated with undertaking work at height.
The installation of any roof-mounted PV array will naturally increase the future requirement for roof access - whether this be for routine inspection and cleaning of the PV modules, or maintenance and upkeep of the main roof and gutters. Managing the hazards connected with these works are just as important as managing any other hazard and it is essential that those involved with the planning and design of the roof and the PV installation meet the current requirements of CDM regulations.
Safety is paramount
Roofing systems that are subject to periodic access should be certified as fully walkable - to minimise the risk of damage from foot traffic. They must also be tested for non-fragility in accordance with the latest principles outlined by the Advisory Committee of Roofsafety (ACR[M]001:2014 'Test for Non-Fragility of Large Element Roofing Assemblies (fifth edition))'. If the complete roof assembly - inclusive of rooflights - has not met the requirements of this test, it must be assumed that the roof is fragile - unless the supplier of the roof assembly can provide test data to prove otherwise.
By specifying a non-fragile roofing system, which has met the requirements of the 'Orange Book' (ACR[CP]001:2014 Rev 4 Recommended Practice for Work on Profiled Sheeted Roofs'), the risk of falling through the roof is reduced.
With the significant uptake in roof-mounted PV installations - both new-build and retrofit - these tests for non-fragility are more important than ever to ensure the safety and wellbeing of roof operatives. This is not just a requirement during the installation of the PV array, but must last for the entirety of the asset. Roof system guarantees and non-fragility periods go hand-in-hand and therefore, if the roof system guarantee is compromised, the roof assembly must be regarded as fragile.
In conjunction with non-fragility certification, some modern roofing systems are also classified as 'solar ready' in their standard delivery. This means that, providing the primary and secondary steelwork has the capacity to cater for the additional loadings associated with the solar array, proprietary PV systems can be directly installed onto the roof without the need to enhance the roof system.
Consider the install
Care as to how the PV array is connected to the roof must also be taken, however, and the below list should serve as guidance for facilities managers:
- Encourage the appointed PV installer to liaise directly with the roof system manufacturer to ensure that the proposed method of system attachment does not invalidate any guarantees offered for the roofing system - this also covers non-fragility periods.
- Understand how the installation of the PV system may affect any guarantees for the external roof coating. Most guarantees that are offered for pre-finished steel are only applicable to freely exposed roof cladding. The small print of the coating guarantee should be scrutinised to ensure that any maintenance and inspection requirements are adhered to and roof system guarantees are not compromised, something which, again, may impact on non-fragility periods.
- Ensure that the method of PV attachment does not penetrate the complete roof assembly from outside to inside, which can compromise the weather-tightness of the roof and could lead to water ingress.
- When designing panel layouts, consider the proximity of PVs to rooflights and external sheet detailing in order to maintain routes of safe access for future maintenance and inspection requirements - seek advice from the roof system manufacturer.
- The increased activity on the roof around the PV array means that the roof cladding is more prone to damage. Specifying a roof cladding system that is classed as walkable can provide added protection, as well as ensuring that the PV installer is trained with work on profiled metal roofs and knows how to traverse them.
- Ensure that the extra dead load and wind loadings, created by the PV modules, can be accommodated by the roof system and the supporting frame.
- Clarify what guarantees are offered for the PV system. Does this cover workmanship and equipment (PV modules, inverters) and so on?
Andrew Brewster is project development engineer for building envelope company CA Group Limited