Author Topic: Solar panel fires in the news in the UK after an alleged 60% increase in 2025.  (Read 5318 times)

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Online paulcaTopic starter

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They are allowing the installers to attach the new inverter cabling between the meter and the main breaker, so the meter does see the solar output going to the grid. But the horror to me is the connection method being allowed which is an insulation displacement / piercing connector that is starting to make news here due to fires that it causes. This helps retrofit installations, but it is dangerous in my opinion as seasoned a power electronics guy.

It's quite different in the UK to the US.  We have NEVER had "net metering".  In fact "net metering" is 100% illegal with up to 5 years in prison.  "Backing, slowing, or rewinding a meter is a criminal offence."  That includes generating power on your consumer side with a generator or solar system.

In the US, as I understand it, until regulations have begun to tighten, "net billing" and even "meter back winding" and "negative" bills where the most common.  If you consumed 1MWh and generated 2MWh the electric retailer ended up paying you.  I believe the first punch in the fight came from retailers leveing "standard rate charges" on people.

In the UK to legally "push" to the grid you need a proper feed tariff meter that will record both incoming and outgoing separately.  So the solar power you use up locally is invisible to it, however if you start pushing current outward overall, it will record this on a separate register.

The bill is then assessed on what you consumed at the tariff rate and what you produced at the "feed in tariff rate".  The two are combined to get your net bill.  Standard chargers etc are then added. 

Without a fancy tarif and a lot of hunting a typical setup here might be that "I pay 23p per kwh consumed.",  "I am paid 7p per kwh I produce".

Some people rage over this.  I don't as I have worked on the layer between retailer and distribution where the "per kwh figure" is broken down into what it constitutes.  The actual cost of the electric and it's generation is a small fraction of that figure.  A large part is in "Distribution and transmission costs" and other fees and levies.  This makes sense if you consider from the generation, transmission, distribution point of view, once that is in place, the generator is running, the running costs of fuel per kwh is tiny.   Getting it up and running, keeping it running and keeping it responsive to the demand is the largest part of the cost.  Of course the retailer is paying 40% of what they are charging you, however, retail isn't a 'free to operate business'  call centres are expensive etc.

It should be fairly obvious that more financial tom foolery happens.  After I get paid 7p per kwh those kwh are aggregated by the retailer into what is known as a ROC, which IIRC is a MWh of renewable energy.  So when they collect enough generated kwh they can "sell" that ROC on the market.  Which market depends, but I believe the UK still has access to the wider european energy markets which ROCs are traded like comodities with Buy side and Sell side... and prospectors in the middle.  The thing that strikes me is that a "Buy side" company in this case might be another retailer who will then sell those kwh to customers are "Green energy" at a higher tarif rate.  What is odd about it is, the energy generated, has been generated and consumed LONG ago, days ago, maybe weeks before it's "sold" to someone else to use as if it were "Green".  Like a consumer with a smart meter might be told on a grey, damp, calm winter morning that it's "Big green tick"  "Green renewables available", while absolutely none are being generated.

EDIT.  A point that might be worth raising is that the UK originally had state operated power.  It was split up in the 90s I believe into layers with the generation, transmission, billing, retailing all being separated out to encourage competition and of course privatise most of it.

The downside for consumers is that now there is not one organisation trying to stick the arm in to get profit while cutting service, you have a chain of 3 or 4 all adding their own little part of the pie for themeslves  all paid for by the consumers.   A right little gravy train.  When I worked in the billing side I followed the money down to the "core wholesale cost per kwh" which was 0.12p.  Consumers were being charged 15p.
« Last Edit: November 13, 2025, 05:15:02 pm by paulca »
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Offline mikeselectricstuff

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I want a ground mount system away from my house but the local solar companies REFUSE to do any kind of installation other than on the roof of the home.
The nice thing about ground mount is you don't need to get into scaffolding, roof structral stuff building regulations etc., so very easy to do yourself & bypass all the red tape. 
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Offline mikeselectricstuff

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It's quite different in the UK to the US.  We have NEVER had "net metering".  In fact "net metering" is 100% illegal with up to 5 years in prison.  "Backing, slowing, or rewinding a meter is a criminal offence."  That includes generating power on your consumer side with a generator or solar system.
How is "Slowing" any different from using a grid-tied inverter set up for zero export ?
Did you mean to add ".. without G98/G99 approval"?
I have G98 on my DIY installed setup, set up for zero export.  if I wanted to get paid for export I'd need to pay an application fee and have all the Part P bullshit so not worth the bother.
 
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Offline richard.cs

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The meter is just visible at the centre left, and the two grey cables marked "3N" and "4L" are the metered outputs. These cables go up to the isolator with the red switch and then to the two consumer units so both consumer units are metered.

I was assuming the isolator of the right with the massive black cable was the "presentation point".  Is it the solar incomer?
To be clear this is a random photo I pulled off the internet to show how a second small CU is often connected via Henley blocks in the UK. In this photo incoming is on the left, you can just see the right hand edge of the service head in the bottom left hand corner of the photo (the bit with the exposed earth terminals) and the new CU is top right, with armored cable going from it to whatever it was added for. It may or may not be feeding solar, but this would be a very common way of doing things. As its a fuse and isolator it is more likely a submain to some outbuilding or extension than solar.

Here's another, this one is definitely solar: https://www.positech.co.uk/cliffsblog/wp-content/webp-express/webp-images/doc-root/cliffsblog/wp-content/uploads/2022/02/image-1.png.webp
And here's an example of a small modern consumer unit added in to a legacy install: https://i.sstatic.net/vssQL.jpg
None use IDC connectors. I am not especially against IDC, the DNOs (UK electricity network operators) use them and they're reliable for them so clearly are OK if done well.

Net metering was never officially a thing in the UK though it did happen that sometimes meters weren't changed when solar was added and some types go backwards. Generally when discovered people just got large back bills. Older installs tend to have an import meter (normal meter just one that won't run backwards) and either a generation meter or an export meter, newer ones often don't have separate solar metering at all and rely on in and out being separately recorded by a modern smart meter.
 

Offline mikeselectricstuff

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None use IDC connectors. I am not especially against IDC, the DNOs (UK electricity network operators) use them and they're reliable for them so clearly are OK if done well.
AIUI the main objections to IDC are that they are  normally used for tapping off overhead wires, so not well enough insulated if used inside a meter box, and are not designed/approved for use with the typical double-insulated meter tail wire types.
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Online Marco

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    A friend of mine is installing a large home solar collection system in central Florida and the county is putting him through Permitting Hell.

Florida being that much worse than say Australia is flabbergasting ... and I think Australia is too restrictive to begin with.

How did the US end up with all this code/inspector insanity?
 

Offline Gyro

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...
Here's another, this one is definitely solar: https://www.positech.co.uk/cliffsblog/wp-content/webp-express/webp-images/doc-root/cliffsblog/wp-content/uploads/2022/02/image-1.png.webp

Ouch, a slight diversion but that's a nasty kink in the black DNO service cable going to the service head (bottom right). If it's the standard BS7870 concentric, it has a thick solid Aluminium core surrounded by stranded Copper Neutral. Minimum bend radius 8 x diameter (13mm), so 104mm minimum according to Eland Cables.

I wouldn't be surprised if that goes up before any solar installation, and it's before the service fuse too - straight out to the street main. I'm surprised the DNO didn't fail it when they fitted the meter.

« Last Edit: November 13, 2025, 07:16:24 pm by Gyro »
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Online nfmax

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Shouldn’t the wiring from the Henley blocks to the two distribution units be double-insulated? It’s basically an extension of the meter tails
 

Offline Monkeh

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Shouldn’t the wiring from the Henley blocks to the two distribution units be double-insulated? It’s basically an extension of the meter tails

It is. Many modern tails have coloured sheaths.
 

Offline Stray Electron

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   Thanks for the update. Yes, you definitely have to worry about the induced currents in house hold wiring due to lightning strikes. My friend that is installing the large solar system is the same guy that I posted about a while back that had a lightning strike to his house when he lived in Kansas City. Not only did the lightning blow a hole in his roof and start a fire but it also induced enough current in a nearby copper water pipe that it burned a hole in the pipe that caused the house to flood!  They caught the fire pretty quickly and put it out before it did any significant damage but it took longer to notice the flooding and it caused significant water damage.  He is installing his solar system in a separate building (on a separate piece of property) than his house and that's what lead to the county now telling him that they want him to legally combine the properties before they will allow him to connect to the grid.

 About 35 years ago lightning struck a tree in my neighbor's front yard and went down the tree and somehow reached the sewer line to his house and it followed that into his house and blew out every electrical receptacle and every electrical device in his house! I don't know how it got from the sewer line to the electrical system but it need. They know that it followed the sewer line because where it went under his concrete front porch it broke the concrete and left a clear evidence of the path of where it entered the house.

  Around the same time I had a nearby lighting strike. I don't know what it hit but the horn in my old 1970 car started going off. The car was locked and no one was around and the only way that I could stop the horn was to unplug the relay. Somehow the lightning had magnetized the relay.
 

Offline chasnc

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    A friend of mine is installing a large home solar collection system in central Florida and the county is putting him through Permitting Hell.

Florida being that much worse than say Australia is flabbergasting ... and I think Australia is too restrictive to begin with.

How did the US end up with all this code/inspector insanity?

Florida has had so many house fires and even some deaths due to solar installations, so I believe they are getting overly cautious now. The solar industry is happy making money the way things are right now, so they would prefer not changing things. And we have too many lobbyists here to sway politicians to vote their way.
 

Offline brucehoult

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My friend here that added solar to his home, he just directly asked his insurance company about his solar system. He wishes he asked prior, because the added insurance cost almost ruined the financial investment.

This is another argument for ground mounted panels and a non-"installed" main battery/inverter/MPPT unit that you can simply pick up and throw outside if it starts smouldering.

My Pecron E3600LFP (3kWh battery built in) weighs 36kg, which I can carry for a short distance (and it has good handles). It would take all of five seconds to pull out the shore power cable, the two XT60 cables from the solar panel arrays, and a couple of 3-pin plugs for the things it is powering.

Something with a single 5kWh battery would probably be too much for me to toss outside.
 

Offline Stray Electron

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    A friend of mine is installing a large home solar collection system in central Florida and the county is putting him through Permitting Hell.

Florida being that much worse than say Australia is flabbergasting ... and I think Australia is too restrictive to begin with.

How did the US end up with all this code/inspector insanity?

   I don't really know but the amount of growth around here is absolutely insane and the building codes and the number of ridiculous demands by the local governments are going through the roof.  It all seems to have started after hurricane Andrew and the massive amount of damage that it caused to the piss-poor construction that was then the norm in south Florida.  Now it's almost impossible to get home or building insurance in Florida and the building departments, et al seem to be over compensating by making absurd demands.

    Just last week the local city complained about the sign in front of our building being too close to the road. That sign has been there since 1946 but about a year ago they widened the road and moved it three feet closer so the sign is now three feet too close (17 feet instead of 20) to the road. But the city is demanding that we tear down the sign and move it but there is a 35 foot flag pole next to to it so both the sign and the flag pole and the main water line and an electrical line and two very large concrete anchors would have to be removed and relocated in order to move the sign 3 feet.  And no, it's not "grandfathered in" according to the city. 

   One very good small local restaurant just pulled up stakes and left town after the city demanded $18,000 just to hold a hearing about weather he should be allowed to put a picnic table out in front of his takeout only restaurant.  This is on a lot that three years ago was a over over grown trash filled piece of property that was an eye sore. The new owner cleaned it up and had a very good take out BBQ restaurant located there but now it's gone.

   The city hired a city manager some years ago and he has brought in a staff of Young Urban Professionals and they're completely in charge now and they are running amuck and the mayor and the elected officials are completely powerless (or may be just too lazy) to stop any of the idiocy.
 

Offline 5U4GB

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We have been seeing a similar 70% increase since 2024 in domestic solar installations but micro inverters are not very popular. I guess it's because they cost more, but also for domestic settings they don't make much sense. Large wall mounted inverters dominate here, the 10kW ones are massive.

The one case where they are necessary is when your roof geometry dictates use of more than two strings.  We went with Enphase (ugh) because of this, first choice would have been SMA, for which our inverter of choice had 63kg of metal dealing with the heat.  Compare this to something like AlphaESS with 100g of aluminium trying to do the same job.  But everyone buys the AlphaESS-type because they're much cheaper, and then gets surprised when they overheat.
 

Offline 5U4GB

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In Aus the biggest problem we had was with water ingress into DC isolators mounted on the roof  & shoddy workmanship.
Now that these isolators are no longer required and the regs around instillation and equipment have been tightened up its not so much of a problem.
Your gov will read our reg book and update your reg book in due cores.

Was going to ask the same thing, what are the UK regs like, and can you do cowboy installs to avoid them?  The requirements and post-install inspection here is pretty rigorous (annoyingly so in some cases, having been written for NMC LiIon rather than LFP which makes it almost impossible to install batteries indoors), but then if you're rural it's much more relaxed, so you can buy no-name Chinese panels with Aliexpress inverters hooked up with CCA cable by your mate from up the road who knows a bit about wiring.
 

Offline 5U4GB

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https://roofingtoday.co.uk/uk-fire-service-tackles-solar-fire-every-two-days/

This seems a fair article.  There are lots of "Anti-Renewable" lobbyists reporting it too of course.

Presumably none of whom understand statistics.  1.7M solar panels (is that actual physical panels or complete installs?), 170 fires, that's a 0.001% chance of a fire per year per panel, and much lower if it's per install.  Now compare this to the fire chance for almost anything else electrical in your house, and then the fire chance for anything at all in your house.
 

Online paulcaTopic starter

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https://roofingtoday.co.uk/uk-fire-service-tackles-solar-fire-every-two-days/

This seems a fair article.  There are lots of "Anti-Renewable" lobbyists reporting it too of course.

Presumably none of whom understand statistics.  1.7M solar panels (is that actual physical panels or complete installs?), 170 fires, that's a 0.001% chance of a fire per year per panel, and much lower if it's per install.  Now compare this to the fire chance for almost anything else electrical in your house, and then the fire chance for anything at all in your house.

Yea.  Now go and search for other publishers of the story and you will find a large number of them are far worse and have an anti-renewable agenda.  To them this is a perfect excuse to ban them and double down on oil.
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Offline johansen

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He could have even used a separate transformer there in the outbuilding and provide a separately derived ground right at the building to help attenuate the common mode voltage a lightning strike. Another plan is to use lightning rods, but the H fields during a strike then become an interesting problem. Keep the rods and ground cables away from the house or the electronics in the house can be damaged by induced voltages (parallel wiring to the lightning ground wiring).

the transformer will only help with a ground strike located some distance from the solar array.

it takes a lot of ground rods (most people don't have near enough) to get a 1 ohm resistance and when you have 20,000 amps you've got 20,000 volts which will arc across most any average transformer.

the wire insulation will survive 20kv (but not 100) so its going to conduct it into the house, where, a second set of MOV's can hold it to ground, but ground is still going to be in the several thousand volt range plus the 350volts for the MOVS's clamp voltage, if you only have 2 standard ground rods.

so, you still have current flowing out through the other connections, like say, your cable modem.
in my parents case, the cable connection the isp provided was 1/9th the resistance of the neutral line the utility provided. so it also carried some of the neutral current all the time out of the main panel, being grounded at both ends.

in another case, a utility line broke (7200 volts) and it fried a phone line buried 18 inches in gravel under our driveway. my sister got within a few feet taking a video of the broken line jumping around as the magnetic current moved it. (this would have been 2007 ish time frame). unfortunatly the video has been lost lol. but she is lucky to be alive.

anyhow point being, 7200 volts killing a phone line 18 inches away in the dirt. its not un common for a direct lightning hit to destroy all of the electronics in your house.
« Last Edit: November 14, 2025, 10:09:07 pm by johansen »
 
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Offline Gyro

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The linked issue of Wireless World documents a lightning strike being able to jump 2 metres to internal building wiring from a lightning conductor with an 8 Ohm ground resistance...

https://worldradiohistory.com/UK/Wireless-World/80s/Wireless-World-1984-10.pdf
Best Regards, Chris
 
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Offline 5U4GB

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Random comment on the writeup, they don't disclose the location "for security purposes" but mention that it's been featured on numerous TV programs.  "Here's a church that the entire country has seen on TV numerous times, but we don't tell you which one it is for security purposes".  And it's definitely not in Chorleywood, Hertforshire, so don't even think of looking for it there.
 

Offline Gyro

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Remember that it was written in 1984, when the church's identity would only have been to the locals and respectful enthusiasts, the internet was a mere twinkle, and successful TV program locations weren't descended on by hoards of American tourists.
Best Regards, Chris
 

Offline johansen

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The linked issue of Wireless World documents a lightning strike being able to jump 2 metres to internal building wiring from a lightning conductor with an 8 Ohm ground resistance...

https://worldradiohistory.com/UK/Wireless-World/80s/Wireless-World-1984-10.pdf

Before jw became mentally ill and killed the fieldlines forum, there was photos and detailed account of what was likely a rare positive strike, direct hit to someones wind turbine (which by nature has heavy copper into the house. The strike vaporized the #8 copper buried in the ground and went side ways through the house indirectly hitting the person inside, and continued on, leaving its arc path etched into the walls and floor and ceiling as it found its exit path into the ground on the otherside of the house.

The person survived. The vaporized copper blew the dirt out of the ground on top of it, so no need to dig a new trench. This was about 12 years ago wish i saved the account and photos.

I had intended to edit my prior post

The dc ground resistance does not apply to the first 10 milliseconds of a lightning strike!
« Last Edit: November 16, 2025, 01:35:02 am by johansen »
 

Offline Stray Electron

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The dc ground resistance does not apply to the first 10 milliseconds of a lightning strike!

  I can believe that!  I had a pine tree that lightning hit and it run down the tree and then jumped about three and a half feet through the air to the 4x4 inch wooden post that my mail box was mounted on. It literally blew the hell out of the post!  It exploded into hundreds of wooden splinters anywhere from about two inches to eighteen inches long and it threw them about 25 feet in every direction.  The post had been about five and a half feet long with about one and half feet in the ground. The part in the ground survived but only about eight inches of the top of the post survived, the rest of it was reduced to splinters. The pine tree survived as well except for a very obvious scar about two inches wide all of the way down the tree. One of the odd things that I noticed was that there were no burn marks on the tree or any of the post's debris that I looked at. It simply blew the bark off of the tree in a strip about two inches wide all of the way up the tree. And FYI there was no damage to the metal mail box and no signs on the grass of what had happened.

  I can only imagine what a strike like that would do to somebody's solar system. Or their house too if it happened to be mounted on their roof!

  The only thing that I can come up with is that the rise time of a lightning pulse is so fast and the voltage and current are so high that capacitance and it's effects dominate instead of resistance.
 

Offline brucehoult

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I can only imagine what a strike like that would do to somebody's solar system. Or their house too if it happened to be mounted on their roof!

My take from that is it's not even worth trying to protect against lighting, because it's not going to work anyway.

My house roof is lower than a hilltop about 200m away, with fences and troughs and water pipes on it. There is also a 50m long bamboo hedge about 4x taller than the house, 15m from the house. And my solar panels are on the ground (20 cm high on one side 40 cm on the other).
 


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