PV installations — fire service switch and DC marking (§712)

The PV solar guide describes the installation requirements for solar panel systems, including the disconnection relay against islanding. A separate point of attention is the accessibility of the installation for emergency services in the event of an incident — a PV system, after all, continues to generate voltage as long as light falls on the panels, even when the mains supply has been switched off.

Mandatory warning stickers

Since NEN 1010:2020 (in effect since April 2021) it has been mandatory to apply warning stickers at PV installations and battery storage systems:

• A marking at the supply point of the electrical installation and at the electricity meter, indicating that a PV installation and/or energy storage is present.
• A permanently applied indication at every access point to live parts on the DC side of the system.

The purpose: everyone who approaches the installation — from a technician to a firefighter during an incident — must be able to see immediately that a PV installation is present, and that the DC side can remain energized even after the mains supply has been switched off.

Fire service switch for larger rooftop systems

For larger rooftop installations (in practice recommended from > 5 kVA), a readily accessible fire service switch at ground level is recommended, with which (part of) the PV system can be switched off. This switch must carry the same marking as prescribed in NEN 1010.

Note: the recommendation for a fire service switch comes from the risk-management guidance of the fire service (NIPV) and is a recommendation, not literal NEN 1010 text — the mandatory warning stickers do follow directly from NEN 1010:2020. The exact threshold value and implementation requirements are partly determined by the local fire service/safety region.

Practical relevance

For a horticultural business or company hall with a large PV roof, the presence of a clearly marked, accessible fire service switch and correct DC marking is directly relevant both to one's own safety in the event of a fault or fire, and to the speed and safety with which emergency services can intervene — a DC side that remains unrecognizably energized poses a real risk to firefighters.

Common mistakes

1. Applying no or incomplete DC marking at access points to live parts — a technician or emergency responder is then unable to see that a component remains energized after the mains has been switched off.
2. Placing a fire service switch that is not accessible from ground level — in the event of an incident, the switch must be reachable without having to access the roof.
3. Assuming that switching off the mains supply de-energizes the entire PV installation — the DC side between panels and inverter remains energized as long as light falls on the panels.

Related

• PV / solar panels (§712)
• Home batteries & energy storage systems