Fire Safety Issues with Roof-Mounted PV Systems

6 replies [Last post]
meby's picture
Joined: 2012-04-17

A couple of high-profile fires at buildings equipped with roof-mounted PV systems has created serious concerns for firefighters. The concerns relate to limited access on the roof space and shock/electrocution hazards from the panels. Some states are considering enacting laws to help protect firefighters from these dangers. The 2014 NEC includes a provision for rapid shutdown of PV systems on buildings. Is this one rule enough or should additional requirements be adopted?

Rvincent's picture
Joined: 2014-03-10

Mass has adopted 2014 NEC. As inspector and PV installer, I am seeing a lot of confusion. Code does not address where this rapid shutdown disconnecting device needs to be. If put on the roof, how does the first responder know were the shutdown is. Some companies are installing these solar edge optimizers, claiming they meet this RSD requirement. The manufacture said it can take 3 to 5 min. to de-energize the inverter capacitor banks, which does not meet the NEC 690-12 10 sec. requirement.

journeymanjoe's picture
Joined: 2014-02-19

Section 690.12 Rapid Shutdown of PV Systems on Buildings only removes power from conductors entering the building, it will not remove power from the panels. The panels will only stop producing power when removed from the sun, so the best course of action would be to train the fire fighters in the dangers present from PV panels during daylight fires.

Rvincent's picture
Joined: 2014-03-10

These optimizers are similar to micro inverters, they don't change the voltage from DC to AC but do control the voltage that leaves the module. If each module gets an optimizer and the AC disconnect is turned off the DC voltage will stop at the optimizer, nominally mounted on each module. The voltage that will be present will be coming from the inverter's capacitor bank.

Kadeselfer's picture
Joined: 2014-03-20

I think this is enough. There is no solution to banning the solar panels from roofs since they are a useful source of energy. Firefighters should be very careful operating on this type of buildings.

davidmorris's picture
Joined: 2016-09-06

I think the auto power shutdown will be the best way to prevent this kind of hazard.

Tcr Builders's picture
Joined: 2016-10-27

Regardless of the materials used in the construction of a PV panel, the system will increase fire spread across a common roof assembly.

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