Fire safety and PV

jagec

Hi,

I came across an interesting article recently concerning the issues with (roof-mounted) solar systems in the case of a house fire.

Link

The upshot of the article is that firefighters are somewhat nervous about having hundreds of volts of live DC up on the roof (upstream of the DC disconnect) when they are going to be hacking holes in things and spraying water around. The article might be a little overblown (no, solar panels are NOT energized at night), but it is a valid point.

What are your thoughts on the matter? Is this just another example of the myriad ways in which common household items which can pose a threat in a fire, or would it be a good idea for solar installations to attempt to address the issue?

It does come to my mind that this is an unsung advantage of the Enphase system...with per-panel grid-tied inverters, when the grid is down, there is NO high voltage anywhere, sun or no. If only they were more cost-effective!

BB.

Re: Fire safety and PV

Yes, there are issues with solar panels on roofs... And there have been fires caused by (apparently) correctly installed solar panels (failed wiring can cause a sustained arc which can cause a fire).

However, towards the second 1/2 of the article about:

Even if it’s nighttime and the solar panels have not been exposed to direct sunlight for several days, they still are energized and can kill you. It is estimated that the panels would need to be covered with an opaque tarp for 7-10 days before the panels will “de-energized” down to minuscule levels. (although the handouts specify that this as an option for safety steps - it is not accurate per the presenter)

Gets a little ridiculous... Then they might as well let house burn that have old style picture tube TV's, motor start capacitors, and any devices with DC capacitors or batteries.

Forget the stored energy in a UPS, laptop computer, off-grid/emergency backup, stored fuel for gensets, natural gas lines, propane tanks, cars and trucks on property, electric/hybrid vehicles, air bags, that ~1/2 the homes in the US have guns (must be gun powder and ammunition), etc... Wonder about insecticide/hobby chemicals/cleaning chemicals, paints stored in the garage, etc...

My guess is that fire fighters on roofs/going through burning/burned buildings is still more hazardous than solar arrays.

Does Enphase/micro inverters offer some possibly safety advantages... Yes. Has any fire fighter been injured in New Jersey by solar arrays--from the article no. I don't remember anything in California about injury to fire fighters either--but I have seen articles about a handful of fires started by solar arrays with central grid tied inverters. And we had one thread here were a small house fire was started by an illegal (not to code) solar array (basically appeared to a DIY array or some weird mfg. array).

The final question which was asked really put things in prospective - someone asked that since Califorina is number one when it comes to Solar Panel Syatem installations, “…what do their Firefighters do when a structure fire involves these systems?” Answer was “… they let it burn!”

Would I outlaw/let homes burn because of high voltage solar arrays and central inverters/backup/off-grid power systems? No...

Otherwise, we might as well ban fire stations... Google shows 395,000 hits for "fire station burns".

Some of these articles boarder on the unbelievable:

Fire station burns down for the second time

An early morning Sunday fire on January 11th at a fire station caused 2 million dollars in damage and destroyed all six of it’s fire engines.

This isn’t the first time the German fire department has burned down, in 1994 another fire destroyed the building and all of it’s fire engines.

250 fireman from nearby cities had to drive to the Syke fire station to control the blaze.

Due to the quick response of other fire stations only the vehicle bay and all of the fire fighting equipment was destroyed. The kitchen, offices, and lounges were saved.

One local complained that a fire station that can’t even save it’s own fire engines doesn’t exactly inspire confidence.

Police are investigating the blaze to determine the source of the fire at the fire department.

In our state, we have had a number of huge (and small) fires caused by power lines and brush... One poster here said that their local utility is so lawsuit adverse that they shut down their power lines during heavy winds (and the poster now needs an off-grid backup power system to have power during these multi-hour to possible multi-day outages).

So one solution (turn off utility transmission lines starting fires in high winds) spawns more of what others are trying to prevent (roof mounted solar panels and off-grid/backup power systems which endanger firefighters).

Life is risks...

-Bill

Cariboocoot

Re: Fire safety and PV

On the whole, firefighters are in greater danger from the stored chemicals found in most homes than from a solar array - or any other electrical source. Their gear does a very good job of insulating them from electrical hazards, but there's little protection from an exploding can of propane stored with the camping equipment in the closet.

russ

Re: Fire safety and PV

Enphase - Myphase - Yourphase - none have anything whatsoever to do with any of this.

This type of stuff goes viral and all the boys and girls get excited about it - until the next tempest in a tea cup comes along.

I remember a buddy who is a fireman telling me that firemen do not like home shops at all - they have no idea of what kind of chemical or gases are stored there - he said that was 'scary'.

niel

Re: Fire safety and PV

sounds like a bit of paranoia to me. there are hazards galore in any house that are far more dangerous including, but not limited to, all of the spray cans one has, be it paint, deodorant, etc. i also believe there is a bigger hazard of firemen being on a roof that may have developed a small leak that can weaken that portion of the roof and can allow that fireman to fall into the structure. at least with pvs there he could possibly have something to grab on to. i'll take my chances in places with pvs installed any day of the week even if the smoke didn't block the sunlight from reaching them to produce power during a daylight fire.:roll:

to those that read this and don't know, pvs do not store power. if they did we wouldn't need batteries now would we?

call it deja vu, but i seem to recall reading that article before.

xiphias

Re: Fire safety and PV

FWIW, Tigo systems have a "PV Safe" feature that allows the array to be deenergized from a big red button on their management unit or remotely via web interface. To make either really useful, though, it would need to be made known to the responders where the functionality is located on the premises. Preferably before the event....

jagec

Re: Fire safety and PV

niel wrote: »

i also believe there is a bigger hazard of firemen being on a roof that may have developed a small leak that can weaken that portion of the roof and can allow that fireman to fall into the structure. at least with pvs there he could possibly have something to grab on to. i'll take my chances in places with pvs installed any day of the week even if the smoke didn't block the sunlight from reaching them to produce power during a daylight fire.:roll:

That's a good point: roofs with PVs installed are probably more sound, on average, than roofs without, since part of the installation process is an engineering analysis to ensure that your roof is new and well-built enough to take the extra weight of the panels!

XRinger

Re: Fire safety and PV

"Even if it’s nighttime and the solar panels have not been exposed to direct sunlight for several days,
they still are energized and can kill you."

LOL!! Where do they get this stuff??

Are fire departments looking for more money? So they can fight fires
at homes with solar panels?


Being killed by a lightning strike seems much more likely..
When I was a fireman, I never liked climbing aluminum ladders during rain storms..
But, it was part of the job. Which comes with all sorts of risks.
Which is the main reason I never really considered a career in fire fighting.

peakbagger

Re: Fire safety and PV

I have a small fire deparment in town with a paid chief, with on call volunteers. There are a couple of solar systems in the area of various types. I found a slideshow on one of the solar websites that were developed by a professional firefighter and sent the link to the local chief who used it for part of their monthly training. I cant find the link but I suspect that if someone searches for it, it would be worth sending to the local fire cheif. Alternatively it may be worth having the chief come visit and reivew the basics.

BB.

Re: Fire safety and PV

The same article was going around fire fighter forums too... Here is one thread. Note that this guy has a pretty good summary and that he mentions to not forget that some solar panels are thermal/hot water with its own issues:

I wanted to offer some clarity to this discussion. It is an area we all need to know about, but as is often the case; a few misconceptions can spin some VERY tall tales!

I will address the issues one by one:
1. Panels are only energized in daylight. Overcast days too, but NEVER at night. Scene lights will NOT energize the panels.

2. If the panels, or the roof are on fire you will not get shocked by spraying water on them. Put the fire out.

3. The voltages of panels are are anywhere from 24-48 volts each and generate from 125 to 200 watts in optimal conditions.

These panels are "strung" together in series to increase the voltages to 120 vdc to 400 vdc. While 600 vdc is possible, it is pushing the UL ratings of the enclosures, wire, etc.. The current of these strings is usually from 5-9 amps. And that is only when there is a load (or put more simply, the inverter is sending the power back into the grid). If the inverter is off, there is no current only voltage, i.e. open circuit.

4. The inverters that change the power from DC to AC, are powered by AC. If you shut off the main service breakers, the inverter is OFF and there is NO AC power being sent into the structure. There are capacitors in the inverters that can hold a charge for about 5 min, but in the daytime the panels are producing power anyway. When the sun goes down. Everything is de-energized.

Here is the danger: There is ALWAYS energized DC power in the conduit from the panels to the inverter IN THE DAYTIME. So, secure all utilities (per SOP's) and stay away from the panels, and the conduit in the daytime.

5. Do not break a panel with your axe! Each panel in the string could be carrying the FULL VOLTAGE of that string (120-400 VDC), so if you put an axe through it, you will very likely be getting the rest of the shift off! Don't do it....There is no need to do it, vent somewhere else, and kill the utilities at the main panel.

6. There are often junction boxes on the roofs (residential systems), but these do not always have fuses. If you do pull a fuse under load, you can cause a fire. Don't do it...Bad idea.

7. In California, we will not let a house burn because it has PV Panels on the roof. I may not be able to put my hole in the best place, but I will put one in where I can.

As to the comments on water heating systems, they are pressurized to 15 psi if they have antifreeze (food-grade glycol) and up to 60 psi with water only, so while the water can be as high as 180 degrees F, there is not high pressure involved.

A little about how I know this:
I teach classes on FF Safety on PV Systems, have a degree in Solar Technology, and I have PV and Solar water heating systems myself. I am also a member of the California State Fire Marshals PV Task Force.

I hope that helps. The article that started this has caused many people in both the fire service and the solar industry a lot of stress. It makes us look uneducated.

Stay Safe Brothers!

FE Matt Paiss, Truck 13B
SJFD

The only thing he does not type about--that I think always needs to be addressed--is that some solar systems may have a battery bank too (i.e., the Off Grid / Hybrid system)... A battery bank full of hydrogen, sulfuric acid, and a tremendous amount of potential energy (high current) is, in my humble opinion, a larger risk that low or high voltage solar panels on the roof.

If I was going to have labeling requirements--I would forget the "stupid" generic warning labels they slap on Grid Tied systems and, instead, require placarding Battery Backed systems with more than 100 AH of 12 volt battery banks (i.e., just above what you find in the typical car parked in a garage).

Another article does highlight the secondary issues that can bite a firefighter:

I had been working with the Arizona Public Service (APS) and the Salt River Project (SRP) on a program to identify high-voltage electrical vaults and substations within Phoenix. About a year ago, Phoenix Fire responded to a reported fire in the basement of a residential high-rise building in downtown Phoenix. After arriving on-scene, firefighters forced entry into an “unmarked basement” and began extinguishing a small fire involving what appeared to be electrical equipment. When the electrical company arrived, it was discovered that the “basement” our fire crews were working in was actually an electrical vault. In addition, the equipment involved was a high-voltage transformer. Fortunately, a lighting strike had damaged the transformers, and they were not energized. Had they been energized, discharging a dry chemical extinguisher on this equipment most certainly would have led to electrical injuries to our firefighters, at the very least.
...
In 2002, a firefighter in Switzerland was injured as the result of an electrical shock he received from a PV; fortunately, the injuries were not serious. In 2007, a firefighter in Sedona, Arizona, received an indirect electrical shock while fighting a house fire. In this case, the home electricity was secured at the utility box. The firefighters operating at this incident were unaware that the PV system was still energized.
...
It’s also important to remember that environmental factors can affect a PV system’s performance. Cloud cover, smog, and temperature are just a few things that can reduce the amount of electrical energy created by a PV system. Although the time of day and the weather can affect PV performance, firefighters should always treat the system as if it were energized electrical equipment.
Whenever the sun is shining, a PV system is creating electrical energy, and it can’t be turned off. A fire department in California attempted to black out a PV system by using a salvage cover to block out sunlight. The energy created by the system was reduced, but it did not completely block out the sun, and the system still produced enough electricity to shock a potential victim. Firefighters in Germany attempted to cover solar panels with foam to block out the sunlight, with a similar result. Sunlight was able to penetrate through the foam, and the PV system continued to create electrical energy. In this case, the foam kept sliding off the panels. The bottom line for the fire service is to treat the system as any other electrical equipment and assume it’s energized.
...
Also, the “hot stick” many fire departments carry on their engines and ladders detects only alternating current; using a hot stick to determine if a PV system is energized will mislead firefighters into a false sense of security because everything between the solar cells and the inverter is direct current. Some PV systems include batteries that store the solar-generated electricity. Do not cut into these batteries, and keep in mind that if they are exposed to fire, they will release corrosive fumes and gases. Additionally, if these corrosive fumes come into contact with certain metals, they will produce explosive gases and toxic fumes. When responding to emergencies involving batteries, always wear full protective turnouts and SCBA.

The article also mentions weight (not a problem, panels are only a few pounds per square foot--an AC unit on the roof is more dangerous). And that burning solar panels can release toxic smoke too...

-Bill

solarix

Re: Fire safety and PV

We had an incident 3 years ago in our area where a fireman was electrocuted (injured only) from an off-grid system when he was on the roof fighting a fire there.
The local fire departments have not held it against solar - thankfully. No additional regulations at least. This wasn't one of our installs fortunately. And we now use the SolarEdge system so isn't an issue with us anymore.
We have been proactive though by approaching the local fire district and offer to put on a sales - no, I mean safety seminar to acquaint them with solar.

Cariboocoot

Re: Fire safety and PV

"Electrocuted" means killed by electric shock. It's important to use the right terms so that people aren't confused/mislead.

I can't imagine any type of off-grid array capable of doing this, as they tend to be low Voltage (under 100) and low current. A grid-tie array running at several hundred Volts might be dangerous in this manner.

Considering the huge number of risks that exist with any burning structure, a photovoltaic system is hardly the worst of them. Wouldn't even make the top 10 in my book.

niel

Re: Fire safety and PV

good articles bill. it still boils down to somebody who is an alarmist that either has paranoid dilusions or has some kind of vendetta going for some reason. bad installer or one of the many solar rip-off artists around maybe burned him? pun intended:p worst case may be the guy who originally wrote that piece against solar is just a plain idiot. who knows?

russ

Re: Fire safety and PV

niel wrote: »

worst case may be the guy who originally wrote that piece against solar is just a plain idiot. who knows?

Look at so many things in life everyday that people buy into without a second thought. We have plenty of idiots who love to go off on rants like this.

Russ

BB.

Re: Fire safety and PV

I have fixed my previous post--I had a cut and paste error and forgot this part--Which I think is very important to highlight the fact that DC voltages cannot be detected with the typical AC sensing Hot Stick used by fire departments:

Also, the “hot stick” many fire departments carry on their engines and ladders detects only alternating current; using a hot stick to determine if a PV system is energized will mislead firefighters into a false sense of security because everything between the solar cells and the inverter is direct current. Some PV systems include batteries that store the solar-generated electricity. Do not cut into these batteries, and keep in mind that if they are exposed to fire, they will release corrosive fumes and gases. Additionally, if these corrosive fumes come into contact with certain metals, they will produce explosive gases and toxic fumes. When responding to emergencies involving batteries, always wear full protective turnouts and SCBA.

-Bill

niel

Re: Fire safety and PV

the bottom line is they need educated on solar at least for the basics.

jagec

Re: Fire safety and PV

niel wrote: »

the bottom line is they need educated on solar at least for the basics.

True, but when it comes down to someone responding to an emergency situation like a fire, I think that we also owe it to the firefighters to make it as easy as possible to figure out what's dangerous and what's not.

I wonder if something simple, like using red-painted conduits for circuits that retain power when the grid is off, might help to keep them from accidentally putting an axe through a high-voltage wire.

It's great to live in an era when we can detect dangers like live current from a distance (referring to the "Hot Stick"), but the quality of instrumentation does make some people complacent, and it seems like the world today has higher expectations when it comes to things being "fool-proof".

niel

Re: Fire safety and PV

sorry, but that's a bad idea for i doubt they will see the red paint in the smoke filled room. it is pretty straight forward in that straight gt systems have no batteries and as soon as power is cut so is the output from an inverter. they can stay away from the pvs in any case just as they might many other things. batteries they may need to watch for, but they aren't as threatening as they are lower voltage dc.

they need a basic education on them and it won't be as simple as painting something red.

Ralph Day

Re: Fire safety and PV

Around here the local fire chief came and diagramed out the off grid systems (mine and others). The volunteer first to the truck would have this book on the truck seat which outlined where/how/what to disconnect and how to do so. Made me feel more comfortable knowing that they were informed about unusual hazards. Usually they'd pop out the utility meter to kill power to a structure on fire. Just hope they could speed read:roll:

Ralph

niel

Re: Fire safety and PV

popping the utility meter would shut down a gt system, so that works. i guess the biggest problem they may face is knowing the type of solar setup it is as that isn't always obvious. they may not know if there are batteries involved or if it's even tied to the grid or not.

Ralph Day

Re: Fire safety and PV

So, assume the worst, hope for the best.

Any house fire may have ammunition cooking off, propane camping cylinders ready to blow, any number of hazards. At least the first responders now have a protocol for isolating the power systems.

This might not appeal to many who are somewhat isolationist/survivalist in their thinking.

Ralph

jagec

Re: Fire safety and PV

niel wrote: »

sorry, but that's a bad idea for i doubt they will see the red paint in the smoke filled room. it is pretty straight forward in that straight gt systems have no batteries and as soon as power is cut so is the output from an inverter. they can stay away from the pvs in any case just as they might many other things. batteries they may need to watch for, but they aren't as threatening as they are lower voltage dc.

they need a basic education on them and it won't be as simple as painting something red.

I was referring to conduit on the outside of the house, especially on the roof. Not that they should be slicing into ANY conduit when they're hacking ventilation holes, but the idea was that if they're waving that Hot Stick at a bit of conduit and it isn't going off, the red color would serve as an indicator that the line was still hot.

I agree that inside the house it would be pretty useless, and that hazard signs and colors are certainly no substitute for education.

Jburgess

Re: Fire safety and PV

jagec wrote: »

I was referring to conduit on the outside of the house, especially on the roof. Not that they should be slicing into ANY conduit when they're hacking ventilation holes....

In the 2011 NEC they added this requirement and explanation for inside DC wiring:

690.31 (E) (1) Beneath Roofs. Wiring methods shall not be installed
within 25 cm (10 in.) of the roof decking or sheathing
except where directly below the roof surface covered by
PV modules and associated equipment. Circuits shall be
run perpendicular to the roof penetration point to supports a
minimum of 25 cm (10 in.) below the roof decking.

Informational Note: The 25 cm (10 in.) requirement is to
prevent accidental damage from saws used by fire fighters
for roof ventilation during a structure fire.

niel

Re: Fire safety and PV

from saws? or do they mean to saws? i guess any other wiring that may be there is ok to mount closer and cut through. if they could they'd outlaw nails on a roof too as it might jab a fireman, but that's not in the electrical department, yet.:roll: