In-Roof PV Panels and Fire Safety

[LnP]

I'm starting a new thread after seeing comments in this one about the risk of fire from PV panels. I'm planning an in-roof system on timber frame. There were some interesting concerns raised in that thread and I'm interested to learn more.

 

I shared a link in that post to guidance from the Fire Protection Association on fire safety with PV installations. It's mostly aimed at commercial installations and doesn't give much specific guidance. There's also a guidance from the IEC but it's quite expensive and I haven't bought it.

 

One of the things the FPA guidance says is that PV panels should be mounted on a non-combustible surface. On-roof would be better in that respect as it's on top of tiles or slates, but would there be any benefit in putting cement fibre board under the panels for an in-roof installation?

 

Any other suggestions to manage this risk?

[Kelvin]

The issue our friends had was the cabling that went into the roof. Theirs was on roof. There was a fault in the cabling which set alight to the roof within the void. The fire damage wasn’t extensive as it was mostly within the roof but the smoke and water damage was extensive which effectively meant the house was rebuilt albeit the walls were deemed to be safe.

 

PV isn’t fit and forget. The cabling and connections should be regularly inspected as a minimum when it’s on the roof it’s harder to do and therefore few folk do it. We have other friends who bought a house with an old PV system on the roof and when he checked the cabling it had become very brittle. 
 

The guide you posted was good enough to consider best practice. 
 

All of that said, as pointed out, it’s very rare and there are other items in your house that pose a greater risk. 

[Dillsue]

44 minutes ago, LnP said:

Any other suggestions to manage this risk?

From the doc linked to- "The incidence of fires involving PV systems is very low" so probably worth keeping things in perspective relative to other hazardous things in your house/life.

 

AFAIK the majority of PV related fires are down to cable connections where cables haven't been terminated correctly so make sure things are tightened up and crimped correctly. Make sure MC4 connectors are crimped with the right size crimper for the cable size but that's down to whoever is doing the crimping. If there's cage clamp terminals in your inverter don't use crimps on the ends of stranded cable as cage clamps are intended to flatten the strands to get the biggest contact area.

 

 

[sharpener]

9 hours ago, LnP said:

Any other suggestions to manage this risk?

 

I put smoke alarm in roof void linked to main house alarm system with remote phone dialling etc as an obvious one. Cables are sized for voltage drop so they are oversized for the current they carry.