How do you safely disconnect Solar PV power in the event of a premise fire

Due to the significant uptake in Solar PV being installed on Residential installations one problem we have incurred is how to safely isolate supply when there is a house fire.

When supply was just via the network any electrical risk could be eliminated by disconnection from the electricity distribution network, now that premises have their own roof top generation system this action does not eliminate the risk to fire services or persons at the installations. We have already had cases where, after fires that occurred at night have been controlled by the fire services, testing has found voltages up to 110 DC on the installation roofs the next day when the sun was out, due to damage that had occurred to the Solar PV array wiring by the fire.

At this stage whose responsibility it is to safely isolate the solar PV system in the event of a serious fault or fire and what is the safest way to do it is something we are still struggling to identify.

We have also had several fires caused by incorrectly wired polarized DC circuit breakers and defective DC isolators. How to safely access and isolate the Solar generation to prevent shock and isolate the faulty DC components is something we urgently need to identify best practice for.

Relay systems can be used to remotely disconnect power from PV systems to shut down power feed from solar arrays in the event of a fire. Some jurisdictions already require manual disconnects mounted near arrays or on roof tops to shut down power. Ground fault detection and proper grounding should also be applied to all solar systems for fire and homeowner protection. As for the faulty wiring and installation issues building inspectors should be on the look out for that problem from the start of the installation.