Rooftop solar system fires
Rooftop solar system fires
(OP)
Just noted this article about fires Amazon has been experiencing. They downplay the gravity of the problem, but have turned off the solar power at all their facilities in the US. Is the problem equipment or installation workmanship?
https://www.foxbusiness.com/technology/amazon-temp...
https://www.foxbusiness.com/technology/amazon-temp...
RE: Rooftop solar system fires
https://ieeexplore.ieee.org/document/9143083
RE: Rooftop solar system fires
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Rooftop solar system fires
https://www.eng-tips.com/viewthread.cfm?qid=492974
RE: Rooftop solar system fires
Turning them off doesn't really help if its the panels that are going on fire. You would have to cover them otherwise they will just sit at max Voltage and be able to produce max current @12 amps when a fault occurs. Wiring issues they can still produce and feed the flames.
RE: Rooftop solar system fires
The MC4 are crimped and not soldered apparently. And they are solid tube crimp. Not fold over crimp.
And we're fitted onsite by contracted installers.
Just checked my panels and they have german sprung loaded cable grips inside them over a s grip. Which I presume allows thermal moving of wire strands and no arc gaps being produced.
Did a search for similar fire events in Europe and there hasn't been any since the regulations about diodes came out.
RE: Rooftop solar system fires
In my experience, crimp connectors done properly don't fail.
Soldered connections can "fail" at the melt temperature of the solder. Proper crimp connections fail at the melt temperature of the metals.
Spring-loaded connectors can fail if the springs lose their temper. I've dealt with it a few times.
Hard to believe, I know; but some installers are incompetent.
spsalso
RE: Rooftop solar system fires
RE: Rooftop solar system fires
It looks like there's either a fabrication error of the product, or an installation error by the installers. Which it is, or both, doesn't seem to be showing up.
On the installer's side, it seems to me that if one of his connections failed, the failure is contained inside a junction box. And one or more panels shuts down. I don't see how a giant fire would ensue. That's why junction boxes were "invented".
spsalso
RE: Rooftop solar system fires
And now you put that into conduit so there is no air cooling.
And now you cycle this each day with a soak period.
Better be some pretty good wire insulation.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
RE: Rooftop solar system fires
And now you put that into conduit so there is no air cooling.
And now you cycle this each day with a soak period.
Better be some pretty good wire insulation."
Typical insulation is rated for 194F. There are higher temp available.
Temperatures of working environments must be included in calculations: various de-rating factors. For example, Table 310.15(B)(2)(a) of the NEC has corrections for ambient temperatures up to 437F.
There is also a correction factor for the number of conductors in the conduit: Table 310.15(B)(3)(a)
Should the insulation still fail, the conductor will be shorted to ground; and a breaker will trip. Any damage will be contained in the conduit.
spsalso
RE: Rooftop solar system fires
RE: Rooftop solar system fires
But start adding panels up, and....
I do agree that the designers of the system should pay attention to "failure to a short". It DOES seem likely that a ground fault system and/or an arc fault system gets appropriate pretty quickly.
spsalso
RE: Rooftop solar system fires
USA there seems to be major work and discussions about arcing industry wide and yet another code is likely to be issued for arc suppression systems and detection.
Solar in Europe and Australia it is hardly ever mentioned and seems to be a none issue. I can't work out why its a big problem in one area and absolutely nothing else where. In fact both those areas run much higher voltage strings than the US which is capped at 600V domestically, We are capped at 1000V domestically and the farms run 1500V strings. But already there is political lobbying that we should also change the codes to include it. I presume its linked to single market requirement economics and if the rest of the markets don't need it then it sticks out like sore thumb and increases costs/reduces choice in that market. Plus makes local suppliers uneconomic outside that region.
When I say sprung the wire is fed across a conductor edge and then the sprung part is another edge gripping the wire so it S through between the edges. So when it heats up and the strands move they are kept in contact. I think the main idea is that it can thermal contract and expand and rearrange itself and the contact area doesn't reduce over time. https://www.farnell.com/datasheets/sunclix.pdf
In this case it may not be the crimp but the quality of the male - female connection causing arcing as they seem to be saying it is the connectors from one supplier.
As for the tripping to ground. We don't have fused/breakered strings in Europe. The wire is protected by the max current able to be produced by the panels which is under 13 amps. You can connect a panel directly to ground and a 16 amp fuse/breaker will do absolutely nothing. German inverters have to have a grounding fault detection system. Which works by the grounding of the panels goes back to the inverter and it uses that to work out if all the electrons are going to where they should be. But all it can do is trigger dry switch which can be linked to a audio or visual warning and send you and email/ flag it in the monitoring system. You can't stop the panels producing power unless you block the sunlight.
I think they also reported that they found when they inspected the other installations they found quiet a few of them not grounded at all. So its more than likely revolves round installation errors across a broad range of topics. Tesla seem to have issues with the in roof domestic solar setups as well in the USA but I can't find any reports in Europe. And we don't have the conduit requirements. In fact my strings just go through flexible plastic tube rated at 1500v through the internal walls of my house down to the cellar. USA seems to require most installations to be piped down external walls.
Construction materials may also be a feature, With our consumer units being made out of plastic not metal along with most of our electrical boxes its pretty much normal to use none flammable plastics for components.
I might add this inability to kill power to solar is one of the political lobbying arguments that enphase are trying to use to restrict/ban DC string inverters and only use micro inverters. And of course they hold the bulk of the patents for micro inverter tech. Its a mess of codes and practises. But engineering wise the problems are varied and region specific. The ones that were global they have tackled eg the bypass diodes and panels going on fire.
RE: Rooftop solar system fires
RE: Rooftop solar system fires
If you have any links I would be interested.
The cowboy issue is rearing its head in the UK there is just so many people trying to get installs at the moment. And a colossal shortage of hardware. The popular brands are 6 months plus lead times. But the brands are restricted for grid tied due to them setting up a cartel qwango of installers/ suppliers which isn't required legally but they have managed to get all the grid DNO's to require it and also house insurance company's. If you have an approved cowboy installer who then walks after a rubbish install of course they will wash their hands of it and say its a civil matter. So 10% price hike for not a lot.
RE: Rooftop solar system fires
RE: Rooftop solar system fires
Media reports:
https://theconversation.com/solar-panel-fire-seaso...
https://www.9news.com.au/national/solar-panel-rela...
https://www.abc.net.au/news/2022-06-05/rainfall-an...
There are many more, but these are all domestic installations, not the big commercial fires reported in the US.
RE: Rooftop solar system fires
I've heard of the term "brazing", but never used it or heard anyone else apply the term. Up until now, my understanding has been that it refers to a joining of two metals using a brass alloy. I've never seen it done.
I have done work called "soldering" by all concerned with the task.
There was what I would call "soft soldering", typically using a lead-tin alloy that can be melted by a hot iron. This would be in the range of 600F-700F. I have typically used it in electronics.
And there was "hard soldering". Also called "silver soldering", since it uses an alloy with a high silver content. This required a torch, typically acetylene/air. Temperature range is 1200F-1500F.
You get a much better bond with solver soldering, if that's what you need. I did an experiment of laying a 12 gauge copper wire across another and soldering the two together with soft solder and another with silver solder. I then hammered them flat. The soft soldered wires separated. The solver soldered wires did not.
I do know there is a silver bearing soft solder, and have used it. In my case, I found no advantage.
spsalso
RE: Rooftop solar system fires
I am more than happy with the possibility that crimping a connector onto a solar wire is outside the skill set of causal labour trained in 5 mins how to use the tool.
RE: Rooftop solar system fires
Just found this for solar fires in the UK.
Not many of them in the grand scale of things.
Interesting that isolators are the main culprit.
The Germans prefer to have a DC disconnect on the actual inverter. Hence I don't have them. There is no fusing in the UK to my knowledge on series strings. But I presume an inline locally install fuse box has the same risk as an isolator. I don't have either.
Connectors next on the list must admit I used sunclix because that's the make on kostal inverter. And the panels came with two mc4 connectors for every 10 panels one male and one female which where also sunclix (panels assembly done in Estonia by NAPs)
My inverter is mount on a concrete cellar wall.And there is a linked fire alarm down there. Many installations you see in solar groups they are in people's attics mounted on fibre board and battery sitting under them on wooden flooring.
But me doing that is more luck than judgement.
Wonder if some of these roof fires are linked to the old school firemen's isolators which are just a remote isolator.
RE: Rooftop solar system fires
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"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
Add fires and I'm wondering if it's a solar storm or coronal mass ejection event. Some transformers got close to catching on fire during previous events in 1989. We are currently at a peak in the 11 year cycle of solar activity. The results of a solar storm just hit earth yesterday https://www.indiatoday.in/science/story/geomagneti...
On the original subject, my gut feel is workmanship / connections. I have been involved in infrared monitoring of electrical equipment for the past 20 years (at least on and off). The vast majority of electrical events (infrared findings, occasional smoke, and rare fires) reported at our power plant were related to connections. Combine that with the current solar environment where we have had high rate of installation over the past decade with demand for lots of new workers and the result is potential for a lot of installation workmanship events. Just my SWAG fwiw...
=====================================
(2B)+(2B)' ?
RE: Rooftop solar system fires
RE: Rooftop solar system fires
Most of the installations are done by cowboys unfortunately.
There were also different 'best practice' aspects that have since been reversed due to issues, such as use of polarised breakers and their subsequent withdrawal.
Having had to do utility mandated inspections on a few installations, there's plenty of opportunity for cowboy workmanship to creep in, and that's without the often seen incorrectly selected equipment that isn't suitable for duty, but still used as the installers don't know any better.
The interesting thing with solar panels is when a short occurs there's enough current flowing to get things really hot but not enough to melt conductors, blow clear or trip breaker magnetic elements. This results in the short sitting there for ages until the material around it gets hot enough to burn.
EDMS Australia
RE: Rooftop solar system fires
Its one of the reasons why I don't like and would avoid any of these modules that sit under the panels be it optimisers or rapid shut down isolators. You double up on the amount of connectors and they will be dissimilar makes between module and panel.
The cowboy stuff goes beyond electrical.
A workmate had a system fitted 2 months ago and ask me to go look at it. he has panel corners sticking high of the roof ridge line, And the wires under the panels are spaghetti with some of them dangling and touching the roof. Others are not touching but the connectors are the lowest point of the loop. Which is just asking for roof problems and water ingress into the connectors. The corners proud of the ridge line he can do nothing about and apparently is local permitted. but the big boss came to see the wires dangling and was extremely upset. The workers turned up on a Sunday unpaid to fix them.
Solar groups in UK are showing pictures of 100mm racking bracket screws which should be through into the trusses just sticking through the moisture board it was lucky the owner spotted the bumps in the insulation. court case now in progress for a new roof. MSC which is meant to be the trade oversight of standards and quality have washed their hands of it and say its a civil matter. Quite what you get for paying 15% more for a certified MSC installer I can't really work out.
RE: Rooftop solar system fires
Are "lack of drainage" and "DC arc in combiner box" not installation errors?
The other factors could also be exacerbated by poor workmanship during installation.
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
That which is done in one country may not be done in another.
For example: whatever a "combiner box" is, in the US they should not be a problem due to "a lot of amps running thru them".
If y'all want to talk about crap installations in far away places (which you may well inhabit), please note where those far away places ARE.
spalso
RE: Rooftop solar system fires
They are the place where multiple strings come through, that's where the fuses/breakers are located, Surge protection for the strings, string monitoring if it's not done and the rapid shut down isolators if required if it's in the attic and also the earthing bus bar and grounding protection stuff. Some also do the paralleling of strings up as well. If there is DC charging of batteries involved there is a whole load of other stuff in there as well.
They are used a lot in the USA due to a code regulation you have. Before about 10 years ago USA mainly used inverters with transformers and required a separate ground spike to the solar which was bonded across to the main house spike. That then went to the combiner box to be used for the surge protection, array grounding and to the inverter DC side.
The transformer less inverters get the ground from the AC side and as such don't require a dedicated earth spike of their own for the DC side. But the fusing, surge protection, Dc breakers, firemans isolator etc are still being put into combiner boxes. They developed over the years into quite an industry and heavily sold as major safety required items. Each box has colossal amounts of connection points between various components handling some very high currents and voltages. And they like to get them as small as possible which is one of the selling points.
The old transformer inverter setups with battery with all the trunking etc you could easily fill up 2m2 of wall with all the bits and bobs that are now included in the purpose made combiner boxes which come in at under 0.5m2.
German codes require all that external stuff to be included inside the transformer less inverter. Europe has never really used transformer isolating inverters. Plus, it's a different setup because we have 230V/400V 1/3 phases and USA has your split phase setup.
The above is what I know on the subject of combiner boxes and I will admit it may be incomplete or wrong in some parts especially surrounding the earth required onto isolating transformer setups.
Some solar setups are works of art with the wiring and various bits and pieces, You look at mine with 5 cables coming down a flexitube from the ceiling into the inverter and it feels very like you have turned up to a gun fight with a potato gun when everyone else has military assault rifles. The combiners can be 500$ plus. Some say but you need to be able to isolate the strings. Only time I have ever disconnected mine after installation in 4 years, was to boot up my second inverter and register it with the grid for the new barn. And due to that being delayed building it and paperwork deadlines, I did a Boeing and borrowed a string of the first inverter to power it up. Connected the AC to the house and internet registered it and then left it for 3 days until I got the confirmation from the grid that paperwork was now complete and then put it back the way it was and the new inverter under my bed.
RE: Rooftop solar system fires
Chinese crap combiner boxes installed in the USA.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
I am talking about an ex soviet state in the EU, with knowledge of how they do it in Germany, UK and a little bit about France mainly due to mates that have systems installed in those countries.
In fact, I should be getting sales bonuses of Kostal and BYD for the number of systems installed I have been involved with. And on a hit list for Enphase and Solar Edge.
RE: Rooftop solar system fires
Chinese crap combiner boxes installed in the USA."
Thanks. And what is the name on those "combiner boxes"? And the model number?
While the UL is not high on my list of integrity-first organizations, I do imagine that every "combiner box" would have to have UL approval to be installed in a solar system.
I can imagine that if an installer installed a non-UL approved item, and it started a fire, the insurance company involved would suddenly divorce themselves from the need to pay out to their insured.
spsalso
RE: Rooftop solar system fires
RE: Rooftop solar system fires
And there is a huge difference in temperature range specification. The 5$ each MC4 connectors are -40 to +85 C the 1.50$ are 0 to 60 degs C.
Not that most consumers would ever look at a tech sheets.
RE: Rooftop solar system fires
Not this again... Do you mean a photovoltaic system?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
An insurance company that had to pay because of a fire from a non-rated box, would likely go after the inspected, installer, and maybe even the finance company. Substandard crap is not allowed, according to code.
The homeowner would not know this, and a licenced installer/electrician/inspector would.
Hoffman boxes are a premium brand, and are not the cheapest, but it might be salt water that you are fighting. The steel boxes work well in the mostly dry country.
RE: Rooftop solar system fires
RE: Rooftop solar system fires
RE: Rooftop solar system fires
‘Photovoltaic’ is an example of sesquipedalianism. We are not all sparkies here.
RE: Rooftop solar system fires
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Rooftop solar system fires
You use "sesquipedalianism" to complain about photovoltaic??!!
These systems are generally referred to as "photovoltaic" or "PV system" or "solar" carefully, without the word 'system' attached.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
Solar thermal is the most efficient and uses vacuum tubes to heat water which is then used.
Photovoltaic produces usefull electrons.
There are a couple of other methods, the most scary one is again thermal which involves mirrors onto a ball heating water to utterly stupid temps and pressures which then gets expanded through a turbine. To produce electrons.
RE: Rooftop solar system fires
RE: Rooftop solar system fires
You mean like this solar thermal farm where mirrors reflect the sunlight onto a series of 'boilers' mounted on towers, creating steam which then turns a set of turbines down at ground level? The picture below shows the Ivanpah solar farm near Ivanpah, CA, just inside the border from Nevada, on the way to Las Vegas:
April 2019 (Sony a6000)
Here's an earlier shot of one of the towers taken while the facility was under construction:
May 2012 (Sony DSC-H2)
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Rooftop solar system fires
RE: Rooftop solar system fires
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
Imagine what offshore wind turbines are doing to birds where they aren't so easily counted when dead?
Animals are harmed by all types of power generation. That is fact. But a serious consideration we need look at is the sudden shift in light temperature from low energy sources such as LEDs. Suddenly we have moved from 1700k to 6000k when transitioning from incandescent to LED. In that same time period there has been a mass die off of insects and I believe artificial late night light is a contributing factor.
RE: Rooftop solar system fires
They have done plenty of studies about on and offshore windfarms in UK and birds. The populations don't show any drop in numbers and no vast numbers of fatalities around onshore ones.
RE: Rooftop solar system fires
RE: Rooftop solar system fires
They have put a lot of work in on minimising it in both Scotland and Norway.
I think one of the solutions was to paint one blade black.
Here is the sort of stuff we see on the subject in Scotland. And there is quite a large anti windfarm movement.
https://scotlandagainstspin.org/2020/10/the-wind-s...
Birds strikes and avoidance of wildlife has been part of my professional life for years.
Windfarms are actually a bit of a risk for aviation. They mess with radar mosaics and also can do nasty things to the lower wind profiles and turbulence. So we do get briefed on them and follow them.
Seems to depend on your definition of vast. Compared to the genocide that cats do to the bird populations its actually a very small amount. More of an excuse for NIMBYs to try and not have them nearby.
RE: Rooftop solar system fires
That's right! Thanks for that.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
https://www.google.com/url?sa=t&source=web&...
It wasn't so much an issue of the number of birds killed but the types of birds. The raptors and predatory birds were most likely to fall victim.
RE: Rooftop solar system fires
Just googled why they call them streamers. Poor birds getting roasted
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
RE: Rooftop solar system fires
We make the blades water-clear so birds can't see them.
I kid. But no black blades.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
--- Best regards, Morten Andersen
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
Aviation wise we hit relatively alot of birds of prey as well because they are not scared of us.
Have sat a few times in a thermal with a bird of prey with it eyeing us. Prey birds high tail it out of there.
This is different to the flocking birds who maximise their individual chances by keeping close together. Aka what sully had to deal with.
We never hit black crows way way to intelligent.
RE: Rooftop solar system fires
Power companies also have to keep track the birds that are killed. But building owners don't. Why?
Shiny buildings injor more birds per year.
There is another type of solar that uses mirrors to focus the sun light onto a pipe. But not so high temperatures.
RE: Rooftop solar system fires
That sounds more like a system for producing, or at least preheating, water for a domestic/commercial hot water system. There's a couple of homes near here who have both photovoltaic and what appears to be panels which have what looks like plumbing running to and from them. I've heard of people installing systems like that to heat their swimming pool.
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Rooftop solar system fires
My recollection was that one option was to build your own (hot water) "panels" from scratch. I don't think there was much out there commercially.
The class was quite interesting. There was discussion of placement of thermal mass and windows and roof overhang and........
spsalso
RE: Rooftop solar system fires
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Rooftop solar system fires
John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Rooftop solar system fires
I suspect it needs anti-freeze, but I don't want to climb on the roof to put it in. Besides what type?
RE: Rooftop solar system fires
RE: Rooftop solar system fires
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
People are also fitting Willis heaters to use with it for filling the full tank.
RE: Rooftop solar system fires
The freeze issues are easily managed with a bit or propylene glycol.
The corrosion issues are a bigger problem. They are easily managed but most lack fundamental understanding of corrosion prevention including those that sell the treatment products (there are steps required to prepare a system for protection).
RE: Rooftop solar system fires
All the better reason to use PV.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
I guess I could use it, and set up some PV to heat the water heating elements.
RE: Rooftop solar system fires
You might find this DIY Solar thread I started interesting reading. I'm surprised it's the largest thread on the entire forum by more than 2x if I'm not mistaken.
direct-to-water-heating
Keith Cress
kcress - http://www.flaminsystems.com
RE: Rooftop solar system fires
RE: Rooftop solar system fires
https://www.stevensonplumbing.co.uk/willis-externa...
https://heatingpartswarehouse.co.uk/product/willis...
They fit them in parallel to the cold input and the top of the cylinder. And it just cycles the water in the cylinder until the whole thing is at whatever temp you like no pump required.
You can get DC immersion heaters versions and they have a temp safety cut out.
Don't have one personally but everyone seems happy with them, usually linked to an Eddi solar diverter. Some have 2-3 in series, and they kick in and out depending on the solar output.
Some run them direct DC as well just limit the series string voltage so it doesn't bust 230V the current will be self limiting any way to under 12 amps 3 kW immersion max current is 13 amps. And they put them on the buffer cylinder, but you need to have mixer valves on every circuit if you do that.
RE: Rooftop solar system fires