SWP - Solar PV and Energy Storage Systems

Operating at a fire or emergency in a building, on a site or on a roof that has a solar photovoltaic (PV) array, a stationary energy storage system (ESS), or both. ESS ranges from a wall-mounted residential battery to a container at a utility site or a battery room in a commercial building. Vehicle and portable batteries are in SWP - EV and Lithium Battery Fire. Guidance in this area changes often; the Hazardous Materials team checks this procedure against the current guidance at least annually (MLITSD, n.d., GN 6-34; MLITSD, n.d., GN 6-53).

• PV: modules are energized whenever there is light, including scene lighting; the DC conductors between the array and the inverter stay live even when the utility disconnects the building, unless a rapid shutdown operates; DC arcs; shock through water streams, cut conduit and tools; roof loading, slippery surfaces and the loss of ventilation area under the array; falling modules (MLITSD, n.d., GN 6-34).
• ESS: thermal runaway and reignition; flammable and toxic gas accumulating in a room, a closet, a garage or a container with the deflagration risk that follows; high-voltage DC; stranded energy; confined space inside containers; fire suppression systems that may discharge (IAFF et al., 2023; MLITSD, n.d., GN 6-53).
• Off-gas treated as IDLH (MLITSD, n.d., GN 6-50).

Full structural PPE and SCBA; thermal imager; four-gas instrument; the site pre-plan and the owner’s emergency response plan; the utility’s emergency number; fog nozzles; a water supply plan; insulated tools and dielectric gloves where carried and tested; fall protection for any roof work per Working at Heights and Fall Protection Program.

A company officer and crew trained in the annual energy-hazards session; the ISO at any ESS incident and any fire in a building with an array where roof work is contemplated; a utility representative requested at every PV or ESS incident; a hazmat officer or the ISO with hazmat operations training for an ESS fire; the site’s technical contact from the pre-plan.

1. Dispatch flags from CAD: array, ESS, EV charging, chemistry and capacity where known. On the 360, look for modules, conduit, inverters, battery cabinets, container units, warning labels, rapid shutdown switches and disconnects. Say it on the radio.
2. Request the utility and the site’s technical contact. Pull the pre-plan.
3. Full PPE and SCBA for every member who approaches a battery or works near energized equipment.

4. Operate the rapid shutdown where installed and labelled, and understand what it does: it de-energizes the conductors from the array to the inverter; the modules themselves remain live (MLITSD, n.d., GN 6-34).
5. The utility isolates the AC service. A building disconnect or a pulled meter does not de-energize the array or the DC conductors.
6. Treat every module, conduit and connector as live for the whole incident.

7. Do not cut, walk on, break, cover with tarps to “turn off”, or remove modules; do not cut conduit; do not pull wiring from an inverter.
8. Water on or near energized equipment only as a fog stream from at least 10 m, never a straight stream.
9. Decision point: is roof work needed? Vertical ventilation on a roof carrying an array is avoided; where unavoidable, cut only in clear areas the array does not cover, with the ISO’s agreement, fall protection in place, and the array treated as live. The array adds load and hides the roof’s condition; the rules in SWP - Roof and Vertical Ventilation Operations apply.
10. Ladders and aerials near conductors observe the limits of approach in SWP - Downed Power Lines and Utility Emergencies.
11. Overhaul around an array is done with the array live; damaged modules on the ground are live in daylight and are handled only with insulated tools and gloves or left for the installer.

12. Identify the system: chemistry (lithium-ion NMC, LFP, flow battery, other), capacity, location (room, closet, garage, exterior wall, container), the emergency stop and disconnects, the suppression and gas detection fitted, from the labels, the owner’s emergency response plan and the pre-plan (NFPA 855, 2026).
13. Shut down: operate the emergency stop and the disconnects where labelled and accessible from outside the hazard; isolate associated PV and charging; the utility isolates the AC side. A shut-down ESS still holds stranded energy and can still run away.
14. Decision point: is the enclosure gas-filled or could it be? Smoke, haze, hissing, a gas detection alarm, a reading at the door, or a fire inside a closed room or container all mean yes. Nobody enters. The ventilation decision is made by command with the ISO on the deflagration risk and the layout, not by habit: opening a door on a gas-filled room can trigger the deflagration, as full-scale testing has shown (IAFF et al., 2023).
15. Defensive unless there is a known, specific life hazard: evacuate the affected area and exposures, protect exposures, cool the enclosure from the exterior from a distance if cooling will help, or let it burn out under watch (MLITSD, n.d., GN 6-53).
16. Thermal imager on the enclosure and air monitoring at the perimeter continuously; the watch period runs hours to days; handover to the owner’s qualified party in writing with the readings, and a return visit arrangement.
17. No overhaul of a damaged ESS. Nobody opens cabinets, cuts, lifts or moves modules (MLITSD, n.d., GN 6-53).
18. A residential ESS in a garage with an EV present is handled under both this procedure and SWP - EV and Lithium Battery Fire; the garage is treated as gas-filled until proven otherwise.

19. Readings and imager observations logged; handover record; exposure reports for every member near the battery or the array; gross decon and post-call station decon; hot debrief; triage under Incident Investigation and Learning Program; the pre-plan updated with what was learned.

• Deflagration: emergency traffic; withdraw; PAR; EHS for burns and blast injury; reassess from a greater distance.
• Member shocked: isolate the source or pull the member clear with a non-conductive tool; cardiac emergency; EHS.
• Suppression system discharge in a battery room: nobody enters; treat the room as oxygen-deficient and gas-filled; ventilation decision as above.
• Module fall or roof failure under the array: mayday procedure; RIT; collapse zone below the array.

Air monitoring log; thermal imager observations with times; handover record; exposure reports; the ESS pre-incident plan (Hazardous Materials, CBRN and Energy Hazards Program toolkit item 6) updated; near-miss reports; triage (Tier 1 every PV or ESS incident; Tier 2 any deflagration, shock, entry to a gas-filled enclosure, or reignition after handover).

Every suppression member: the annual energy-hazards session, with the guidance version recorded; officers: the ventilation and entry decision points in the annual command simulation; pre-plan walk-throughs of ESS sites with the owners annually. The Hazardous Materials team checks this procedure against new guidance at least annually. Sign-off: the program manager; consulted: the JOHSC.

• Program: Hazardous Materials, CBRN and Energy Hazards Program sections 5.9 and 5.10.
• Policy: Policy - Hazardous Materials and WHMIS.
• Procedures: SWP - EV and Lithium Battery Fire; SWP - Downed Power Lines and Utility Emergencies; SWP - Roof and Vertical Ventilation Operations; SWP - Hazmat Entry and Decontamination.
• Forms: Form - Hazmat Entry Log and Air Monitoring Record.

This chapter relies on the following legal requirements, which differ by province and territory. Check your jurisdiction’s section on each topic page before adopting it.

Ontario Ministry of Labour, Immigration, Training and Skills Development [MLITSD]. (n.d.). Firefighter guidance notes (Section 21 Advisory Committee; individual notes revised to 2026). https://www.ontario.ca/document/firefighter-guidance-notes