By the PPA Funding team Last updated
A well-designed commercial solar array is low-risk, but it carries high-voltage DC wiring. Fire safety relies on DC isolators, rapid shutdown that de-energises rooftop cables for firefighters, arc-fault detection, correct cable protection and installation to BS 7671 and relevant standards.
Why does a solar array need special fire precautions?
Solar panels generate direct-current (DC) electricity whenever daylight hits them, so the cables running from the roof to the inverter can stay live even when the building's mains supply is switched off. A commercial rooftop array often runs at several hundred volts DC across its strings, which is why the wiring, connectors and isolation points need careful design rather than treatment as ordinary low-voltage cabling.
The panels themselves are not a common ignition source. Most solar-related incidents trace back to poor DC connections, damaged cables or substandard components, so the fire-safety focus sits on the electrical parts of the system rather than the glass and silicon on the roof.
What is rapid shutdown and a firefighter switch?
Rapid shutdown, sometimes wired to a clearly labelled firefighter's switch, de-energises the DC cabling on the roof so the fire service can work more safely. Instead of live conductors running the length of the building, the system drops to a safe voltage at the array within seconds of the switch being operated.
Placement and labelling matter. The isolation controls should be easy to find, clearly marked, and their location shared with the building's fire risk assessment. Your installer should confirm which arrangement suits your roof layout and what your local fire service expects.
How are arc faults and cabling risks controlled?
Arc-fault detection built into modern inverters watches for the electrical signature of a loose or degrading DC connection and can shut the system down before heat builds. Alongside this, cables should be mechanically protected, correctly rated, kept clear of sharp edges, and fitted with matching connectors to avoid the mismatched-plug faults that cause many rooftop problems.
Installation to BS 7671 (the IET Wiring Regulations) and relevant product standards, plus periodic inspection under a maintenance plan, keeps these protections working over the system's life. Confirm the specific standards and inspection intervals with a qualified electrician or your installer.
This guide is general information, not financial or tax advice. Your circumstances determine what applies — please confirm with your accountant or advisor. Get a tailored proposal →
Frequently asked questions
Do commercial solar panels increase the fire risk to my building?
A correctly designed and installed array adds very little risk. The main hazards come from poor DC connections or substandard parts, which is why accredited installation, arc-fault protection and regular inspection matter. Ask your installer how their design meets current wiring and product standards.
Can the fire service turn my solar system off?
Yes, if a rapid shutdown or firefighter's switch is fitted and clearly labelled. Operating it de-energises the rooftop DC cabling to a safe level. Share its location in your fire risk assessment so responders can find it quickly.
Related guides
- Does solar work in a power cut? Why grid-tied systems shut down, and what keeps you running
- Solar for multi-let commercial buildings: sharing generation between several tenanted units
- How to choose a commercial solar provider: accreditations, questions and red flags
See our funding options, commercial solar and solar by industry pages.