Solar panel fires!

[gimmi80]

kind of scary

[peakbagger]

In my area solar is still rare. When I installed my system, I supplied the local fire chief a link to an excellent presentation that was developed by solar expert that was a firefighter (unfortunately I cant locate it). I believe they went through the slide show during one of their monthly meetings.

[emartin00]

Does the code change mean all inverter manufacturers will implement optimizers?

More likely it will persuade module manufacturers to include circuitry in the modules like the Trina Smart panels.
At this point the 2017 NEC is still just a proposal, so it may not pass anyway. Personally, I think it would be overkill.

[max2k]

As a professional firefighter, I never cause or allow any unnecessary damage caused by uneducated or inexperienced firefighters. I have been a firefighter since 1978. Although solar is rare in Arkansas, measures are always taken to investigate and gather information on new products and ideas. Then we are prepared to accurately address the situation. One thing many forget, solar panels add a weight load to roofs. I am worried about a roof collapse more than an electrical issue from a properly installed solar array. More firefighters are killed/injured from structural collapse than from electrocution.

Many fires occur to improperly installed systems. Once a solar panel starts to burn, it is quickly consumed by flame. Wires overheat due to inadequate sizing, improper type for conditions, loose connections, broken insulation, nail/screw causing a short. Life is dangerous. Danger cannot be completely prevented.

Education will help those making decisions and discussions about solar installations, electrical safety, fire prevention, or anything else that they do not understand. After all, we are all born knowing very little. People not involved with firefighting or procedures used to fight fires do not understand why fires are not always extinguished. Safety of people is always number one. Material things can be replaced, but not the life. If anyone thinks they can do it better, try joining a fire department and try it out in person. I guarantee they will get a new perspective on fires.

Sorry for the rant. Now,,,back to our normally scheduled forum.

Thank you for bringing back some common sense into discussion. It actually crossed my mind that being on the roof in firefighter gear I'd probably be more worried about collapsing roof and getting killed inside the burning house below than some 400- 500V present nearby.

[Naptown]

Hard to say
2104 code says all conductors more than 10 feet from the array have to be below 30 volts within 10 seconds once the rapid shut down is initiated.
I haven't read the 2017 yet but am pretty sure in that version it is all conductors.

[donald]

Both Enphase and solar edge are currently compliant with the 2017 NEC.

Does the code change mean all inverter manufacturers will implement optimizers?

[Naptown]

Both Enphase and solar edge are currently compliant with the 2017 NEC.

[donald]

I came across an article saying NEC 2017 has a proposed module shutdown requirement. That would certainly improve firefighting safety.

[Spiffy Solar]

Education will help those making decisions and discussions about solar installations, electrical safety, fire prevention, or anything else that they do not understand.

Thanks for your input, as a professional in the field. From what I read, the need for education does seem to be the consensus on this subject. What's unique about solar is merely that it is new. There are many other dangers in the the firefighting profession, such as power lines, dangerous chemicals, and much more. These hazards have been integrated into the training regimen. The same will happen for solar. In time.

[firerescue712]

Really?

That is why electrical codes are getting tougher on Solar. Lots of fires.

First thing Firement do with a house fire with solar is get on the roof with a fire ax and smash all the panels with a fire ax. It is the only way to turn them off. That is why CA a electrical building codes requires setbacks on solar panels so fire fighters have enough room to walk around the roof and smash panels.

When Diets & Watson warehouse burned down in NJ, all the fire department could do is watch because the place was covered in solar panels. Not a complete loss, the Fire Fighters had free nice hot meals while they watched. Lots of BBQ on the house of course. .

As a professional firefighter, I never cause or allow any unnecessary damage caused by uneducated or inexperienced firefighters. I have been a firefighter since 1978. Although solar is rare in Arkansas, measures are always taken to investigate and gather information on new products and ideas. Then we are prepared to accurately address the situation. One thing many forget, solar panels add a weight load to roofs. I am worried about a roof collapse more than an electrical issue from a properly installed solar array. More firefighters are killed/injured from structural collapse than from electrocution.

Many fires occur to improperly installed systems. Once a solar panel starts to burn, it is quickly consumed by flame. Wires overheat due to inadequate sizing, improper type for conditions, loose connections, broken insulation, nail/screw causing a short. Life is dangerous. Danger cannot be completely prevented.

Education will help those making decisions and discussions about solar installations, electrical safety, fire prevention, or anything else that they do not understand. After all, we are all born knowing very little. People not involved with firefighting or procedures used to fight fires do not understand why fires are not always extinguished. Safety of people is always number one. Material things can be replaced, but not the life. If anyone thinks they can do it better, try joining a fire department and try it out in person. I guarantee they will get a new perspective on fires.

Sorry for the rant. Now,,,back to our normally scheduled forum.

[inetdog]

I was glad to hear that this thread finally converged to electrical connections being the primary problem and away from other esoteric things like static electricity.

Any connection which is based on an interference fit or smashing of a ductile material like copper is going to be susceptible to oxidation at the point where the current is supposed to go from one contact to the other. The more corrosion the more resistance. The heat generated will be based on P=I^2*R and as Temp goes up so does R increasing T so the whole thing is unstable. You have to keep the R below certain levels.

To a first order, higher voltages are going to be safer as the I^2 effect is reduced by a factor of 1/4 for a doubling in the voltage (AC or DC). But it seems like in a string the DC voltages are even higher than your typical AC.

My question is what is standard procedure in solar installs for electrical contacts (other than set screw torque specs)? Are there sprays (e.g. DeOXit) or greases (Dielectric) used on contacts?

I know house wiring typically has bare wire contacts unless (some water proof silicon filled screw nuts are used) and there are still high currents 10-20 amp. While I'm not an expert, but I'll guess anyway; the AC probably avoids as much corrosion build up at the contact as a DC current might.

The compression connectors are designed to produce what is called a gas tight connection, where there is no opportunity for moisture, oxygen, or anything else to infiltrate between the compressed and form fitting metal surfaces.
For switch and breaker contacts, there is more of a dependence on contact wiping action during the make to break through a thin oxide layer. Copper oxide also breaks down at a very low voltage (hence its early use in rectifier stacks). If the switch is not cycled occasionally the contacts may lose conductivity or weld into position.

[posplayr]

I was glad to hear that this thread finally converged to electrical connections being the primary problem and away from other esoteric things like static electricity.

Any connection which is based on an interference fit or smashing of a ductile material like copper is going to be susceptible to oxidation at the point where the current is supposed to go from one contact to the other. The more corrosion the more resistance. The heat generated will be based on P=I^2*R and as Temp goes up so does R increasing T so the whole thing is unstable. You have to keep the R below certain levels.

To a first order, higher voltages are going to be safer as the I^2 effect is reduced by a factor of 1/4 for a doubling in the voltage (AC or DC). But it seems like in a string the DC voltages are even higher than your typical AC.

My question is what is standard procedure in solar installs for electrical contacts (other than set screw torque specs)? Are there sprays (e.g. DeOXit) or greases (Dielectric) used on contacts?

I know house wiring typically has bare wire contacts unless (some water proof silicon filled screw nuts are used) and there are still high currents 10-20 amp. While I'm not an expert, but I'll guess anyway; the AC probably avoids as much corrosion build up at the contact as a DC current might.

[SunEagle]

Is high voltage DC from the roof in conduit in all states?

Pretty much that is the standard way of running the DC wiring once it is past the panel array and racking.

The wires can be attached using approved "tie wraps" or "clips" to the racking under the panels but you can't run loose wires along the roof so they need to be in some type of "raceway" or conduit.

[inetdog]

Is high voltage DC from the roof in conduit in all states?

On the roof it can be PV wire or other UV safe and mechanically protected cable types. Once it goes inside, especially in an attic, it has to be a metallic sheathed cable or in a conduit, at least until it gets to the first fused disconnect.

The details are in the National Electrical Code, which at least in this subject area is usually adopted without amendment by states or local jurisdictions.
What will vary will be the revision cycle (year) of the code that is adopted.
PV wire was not introduced until the 2011 cycle, for example. (See section 690.31 for a start.)

[donald]

Is high voltage DC from the roof in conduit in all states?