Solar panel fires!

[SunEagle]

All my inside connections are inside steel boxes; not likely to ever flame. But some possible failures
could be difficult and expensive to fix, think inverter. All 15KW feeds through a couple split bolt taps,
which aren't so easy to check being taped up. But I can at least check for warmth by hand and with
my infrared thermometer. Bruce Roe

An IR thermometer or camera is the perfect tool to detect poor electrical connections that have been taped up. As long as you have the camera set up correctly and use the thermometer within the desired distance of your target.

[thejq]

You said the above...

Yes, I did.

And you don't see how the strength of an electric field is relevant? Yeah, there is no point to this at all. Mike's got it right.

Still no. The formula you quoted is for electric field of a current. It doesn't apply to what I said which is static electricity. Again Google is your friend if you don't know the difference. In static electricity, there's no current until the point of discharge. Only potential or voltage matters in attracting oppositely charged ions. Even at the point of discharge, people don't normally use current as figure of merit. Because 1M amps in 1us doesn't say very much. It's normally in joules.

[sensij]

Still no. The formula you quoted is for electric field of a current. It doesn't apply to what I said which is static electricity. Again Google is your friend if you don't know the difference. In static electricity, there's no current until the point of discharge. Only potential or voltage matters in attracting oppositely charged ions. Even at the point of discharge, people don't normally use current as figure of merit. Because 1M amps in 1us doesn't say very much. It's normally in joules.

The formula I originally supplied was for voltage drop, and was from a source that erroneously equated voltage drop with electric field. That was a bad mistake on my part, and I've replaced the equation with a paper that properly calculates the static electric field generated outside of a current carrying conductor. The equations are more complicated, but the cliff notes version is that for an ideal conductor, there is zero electric field outside of it, but in the real world, there is some charge density that builds up on the surface of the conductor that can create a weak field... in this case, orders of magnitude less than the charge generated on glass by wind.

Your use of the phrase "static electricity" is incorrect, and is leading to some mistaken ideas on your part, and some mistaken interpretations of your ideas by me and others. The true fire hazards of DC (or AC) conductors were explained by others much more clearly in the thread, and neither you nor I has contributed much of value to that discussion (except perhaps the article you linked).

[Sunking]

Me thinks someone in this thread needs to by everyone in their home one of these.

[inetdog]

Me thinks someone in this thread needs to by everyone in their home one of these.

I am tempted to censor that post on the grounds that it encourages cruelty to animals.

[bcroe]

Cat

I am tempted to censor that post on the grounds that it encourages cruelty to animals.

I think that is a very unhappy cat. Bruce Roe

[inetdog]

I think that is a very unhappy cat. Bruce Roe

He might just be mad at the cameraman. Or was that a selfie?

[vav925]

whoa!

[max2k]

Yes, I did.


Still no. The formula you quoted is for electric field of a current. It doesn't apply to what I said which is static electricity. Again Google is your friend if you don't know the difference. In static electricity, there's no current until the point of discharge. Only potential or voltage matters in attracting oppositely charged ions. Even at the point of discharge, people don't normally use current as figure of merit. Because 1M amps in 1us doesn't say very much. It's normally in joules.

1M amps in 1 uS says a lot- it means 1 coulomb of charge passed through that point. It doesn't say anything about energy, you're correct. If you knew the difference in el. potential which caused that amount of charge to move then you could find the energy involved.

Dry air arcs at electric field level of 30,000 V/cm AC or DC. You need very high voltage to start arching this way. Static electricity provides such voltages, tens of kV, depending on a cat . Electric charges of the same polarity repel so to get them somewhere you need external force (petting the same cat would do). Sharp electrodes arch easier because of their shape which increases intensity of electric field, not number of charges. Static electricity also doesn't have much energy so when someone get shocked by static he/she generally survives and it is impossible to set building on fire with just static. This all is not relevant to solar due to level of voltages involved.

Another kind of arching is caused by bad contact and high current trying to get through. This possibility is very relevant to solar and also to any other power line carrying current > 1 A. Due to local elevated resistance such spot becomes very hot very quickly as a lot of power get converted to heat due to voltage drop over bad contact. No magic electric or magnetic fields take part in this process. This 'arching' can start a fire if there's something to burn, like wire insulation, jug of gasoline, etc. Solar cells are made of silicon and it is hard chemical to burn- it ignites at temps around 1000 C, a lot of other materials will be burning before that point.

I don't think solar creates any extra fire hazard compare to your conventional power wiring: I had breaker burnt in my hose power panel due to bad contact, I had power wall outlet wire arching inside (very dangerous due to proximity of wood) but that's just life. Some posts in this thread provided very useful advices how to maintain these systems, at kW levels they deserve respect. Micro inverters if I understand this correctly somewhat mitigate the problem by decreasing current level in the common rail due to higher output voltage compare to raw DC output from the panels. Still, somewhere all that energy gets connected together and becomes dangerous.

[Sunking]

I don't think solar creates any extra fire hazard compare to your conventional power wiring:.

I would have to strongly disagree with that statement and any statistician would disagree. Anytime you you buy an appliance, add a circuit, plug anything in you just increased your chances you fire risk. Couple that with the Solar Industry having very low experience levels, little training, human error, and lax electrical licensing requirements all add up to higher risk. Add to that most of the equipment is outside and exposed to the elements and you get the picture.

[SunEagle]

I would have to strongly disagree with that statement and any statistician would disagree. Anytime you you buy an appliance, add a circuit, plug anything in you just increased your chances you fire risk. Couple that with the Solar Industry having very low experience levels, little training, human error, and lax electrical licensing requirements all add up to higher risk. Add to that most of the equipment is outside and exposed to the elements and you get the picture.

Your just being a pessimist.

But I have to agree with your logic.

Adding complexity to an electrical system using low experience workers raises the chances of electrical fires. Of course this is not limited to solar pv installation, it could involve an outdoor spa, water pumping systems or decorative lighting (Christmas) systems that can put a strain on the wiring.

[Sunking]

Your just being a pessimist.

Thank you someone has to do it and inject reality.

Of course this is not limited to solar pv installation, it could involve an outdoor spa, water pumping systems or decorative lighting (Christmas) systems that can put a strain on the wiring.

All you gotta do is watch TV or read the news. The Holidays is a busy time for FD's.

The reason for electrical codes getting stricter and more expensive each cycle is a result of fires. For every electrical code on the books, and all future codes are in response and paid for in blood and damages caused by fires.

I bet most members here think GFCI circuits in wet areas is old as dirt and think nothing of it. Care to guess how many people like babies had to die to get them written into the codes. How many kids got burned,electrocuted, and fatally injured by wall sockets each year? Do you even know in 2008 you are now required to use TR receptacles aka Child Proof sockets as a result.Can you say 2400 children per year or injured or killed playing with electrical sockets. That is almost 3 times as many people that police shoot each year.

[bcroe]

I don't think solar creates any extra fire hazard compare to your conventional power wiring

Unlike most consumer equipment, solar runs quite high power, using facilities not too far
from capacity, for long hours, cycling every day, with no one watching. I think that raises
the chances of a fault a huge amount, with more serious consequences.

I do run a welder, a car lift, some multi horse electric motors. But those have an extremely
light duty cycle, and I am generally right there at the time. The huge majority of my house
wiring is just sitting there for my convenience, doing next to nothing all the time. Bruce Roe

[SunEagle]

All you gotta do is watch TV or read the news. The Holidays is a busy time for FD's.

The reason for electrical codes getting stricter and more expensive each cycle is a result of fires. For every electrical code on the books, and all future codes are in response and paid for in blood and damages caused by fires.

I bet most members here think GFCI circuits in wet areas is old as dirt and think nothing of it. Care to guess how many people like babies had to die to get them written into the codes. How many kids got burned,electrocuted, and fatally injured by wall sockets each year? Do you even know in 2008 you are now required to use TR receptacles aka Child Proof sockets as a result.Can you say 2400 children per year or injured or killed playing with electrical sockets. That is almost 3 times as many people that police shoot each year.

I remember back in 1970 there were > 1000 deaths per year from accidental electrocutions. A lot of people who died were found in a wet crawl space when they grabbed a water pipe that had been accidentally electrified which help drive the NEC to include GFI circuits in more areas around the home.

Another change (which seems pretty straight forward now) was back before the sixties most homes had receptacles with 2 wires. The ground wire was not included.

[bcroe]

I remember back in 1970 there were > 1000 deaths per year from accidental electrocutions. A lot of people who died were found in a wet crawl space when they grabbed a water pipe that had been accidentally electrified which help drive the NEC to include GFI circuits in more areas around the home.

Another change (which seems pretty straight forward now) was back before the sixties most homes had receptacles with 2 wires. The ground wire was not included.

I can still remember, in the 50s asking an electrician what that new 3rd wire was for. Since
then I have changed out an awfully lot of outlets. My earlier experience with the 3rd wire, was
that it didn't make a reliable contact at all. Haven't checked for improvement lately. I much
prefer to rely on GFIs and double insulated appliances. Bruce Roe