32 CONTEXT 185 : SEPTEMBER 2025 guards are an important part of the specification, and it is critical to consider the need for cleaning and care of the installation. Solar installations can also have an impact on bats, particularly by changing temperatures for roosting and blocking access points. There is currently a knowledge gap around the wider impact of installations on bats, but with increasing summer temperatures and extreme weather events, both positive and negative impacts are likely. Along with ensuring that the building remains wind and watertight, ensuring energy efficiency and care of historic fabric, maintenance is an important part of managing the fire risk of PV installations. No system is maintenance-free, although this has been a common statement about PV. Insurance companies are becoming increasingly concerned with the incidence of fire, citing improper installation and lack of maintenance as the primary causes. Roof-top installations, like any electrical system, need regular inspection, but given their location, they can be more vulnerable to storm damage, damage from birds, leaves and other debris collecting on the surface and cabling. It is also important to undertake regular maintenance of the building fabric around the installation. In the case of listed buildings, the potential loss of culturally important fabric should be taken into consideration. The team at York Minster, for example, worked very closely at the planning pre-app stage with North Yorkshire Fire and Rescue and their insurers, EIG, to explore and implement the latest fire safety measures, and to develop an emergency response plan in the event of fire breaking out. In 2022, the Grade II-listed museum We the Curious in central Bristol suffered a significant fire originating from the rooftop PV array, causing millions of pounds worth of damage. The following statement was given on the museum’s website: ‘The evidence indicates that damage to the photovoltaic solar panels was most likely caused by birds, which caused a fault in the electrical system. This then resulted in a fire spreading to the roof… We’ve sustained some significant fire and water damage to the roof, our second floor and our building systems.’ The museum was closed for two years, reopening in 2024. Historic England recommends that a fire-risk assessment be undertaken for PV installations on listed buildings early in the design phases. It suggests that the following are identified: potential fire hazards; people and property at risk; existing fire safety measures; appropriate mitigation measures; firefighting strategy; and main isolation switch to cut off the supply from the system and local isolation, where required. Cleaning solar panels is an essential maintenance task that should be undertaken every 12–18 months. Dirt and dust reduce the amount of sunlight that can hit the panels, so cleaning is essential to maximise generation and efficiency. Many panels claim to be self-cleaning, but this is not really the case, as with any roof surface dust, dirt, lichens and pollen build up over time, especially in drier locations. If access to the array is restricted or expensive, this should be taken into consideration and seen as a potential risk. York Minster has installed an access safe system and implemented a quarterly cleaning regimen for the 180 panels on the minster. This level of care may not be possible to achieve in many cases, especially where budgets are limited or access is complex. Listed buildings and historic sites can and should evolve to accommodate modern requirements and adapt for positive climate action, but success lies in understanding the individual detail of these sites. Taking a holistic approach, considering positive and negative impacts, and ensuring the long-term costs and maintenance requirements of new installations are fully understood and scoped, will ensure that consent is achieved, risk is managed, and our heritage continues to benefit future generations. A fire at the We the Curious museum in Bristol originated from the rooftop PV array. (Photo: Aretta Vesere) Morwenna Slade is a building surveyor and visiting professor at the University of the West of England. She specialises in historic building conservation, defect diagnosis, climatechange resilience and adaptation.
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