Solar PV Electrical Safety

Solar PV systems generate DC electricity whenever exposed to light and cannot be switched off at the panel.
DC voltages in PV string circuits can exceed 1000V, posing a lethal electrocution risk to workers.
DC arcs are harder to extinguish than AC arcs and can sustain a fire at damaged connections.
The Electricity at Work Regulations 1989 apply to all solar PV installation and maintenance work.
Firefighters and emergency responders face electrocution risk from PV systems that remain energised in a fire.
BS 7671 Section 712 and IET guidance set the specific requirements for PV electrical installation.
Roof-mounted PV systems combine electrical hazards with working at height and fragile surface risks.
Inverters convert DC to AC and contain stored energy capacitors that remain charged after isolation.
Cable damage from rodents, weather, or poor installation creates hidden shock and fire hazards.
Only qualified electrical persons with PV-specific training should work on solar PV electrical systems.

Prevent electrocution	PV panels generate lethal DC voltages in daylight that cannot be switched off — isolation requires specific procedures.
Fire risk	DC arc faults at damaged connections sustain fires that are difficult to detect and extinguish on rooftops.
Legal compliance	The Electricity at Work Regulations 1989 and BS 7671 Section 712 require competent persons for all PV work.

Do

Don't

Treat all PV cables and connections as live whenever panels are exposed to any light
Use DC-rated isolation switches and follow PV-specific isolation procedures before any work
Wear insulated gloves rated for DC voltage and use insulated tools on PV electrical systems
Cover PV panels with opaque sheeting to reduce voltage before disconnecting string cables
Ensure only persons with PV-specific electrical training carry out installation and maintenance
Test for voltage at every point of work using a DC-rated voltage tester before touching
Allow inverter capacitors to discharge fully before opening enclosures for maintenance
Install DC isolator switches and emergency shutdown labels as required by BS 7671 Section 712
Inspect all cable routes, connectors, and junction boxes for damage during routine maintenance
Brief emergency responders on the PV system layout and isolation points for the building

DON'T assume PV circuits are dead because an isolator is off — panels still generate voltage
DON'T disconnect PV string connectors under load — this causes dangerous DC arcing
DON'T use AC-rated equipment for DC isolation — DC requires specific rated devices
DON'T work on PV electrical systems without PV-specific training and DC voltage awareness
DON'T open inverter enclosures without allowing capacitors to discharge for the specified time
DON'T route PV DC cables near combustible materials without fire-rated containment
DON'T leave damaged PV cable insulation unrepaired — it creates ongoing shock and fire risk
DON'T walk on PV panels to access cables — panels are fragile and may crack underfoot
DON'T carry out PV roof work without addressing working at height and fragile surface risks
DON'T install PV systems without clear emergency shutdown labelling at all isolation points

See also: DC Electrical Safety (Solar) | Rooftop Solar PV Installation

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