EEVblog #1217 - My Home Solar Power System FAILED!

[EEVblog]

After 6 years my home solar power installation failed!
But *what* component failed? let's find out..

[maginnovision]

If you keep a switch I'd recommend something properly rated. I live in southern california and my junction box(also plastic), which is in the sun 14 hours a day, has never failed in 30 years. There is no discoloration, it isn't brittle, the seal is still good. That or take it out of the loop if you're allowed. If that switch was supposedly rated for that kind of exposure... 

[www2]

I not surprise that this is the reason for the recall.

[m12lrpv]

funny to think that even a simple bit of electrical tape around the seam would have saved it.

[Razor512]

For the switch, why not coat the box with a few layers of car paint and clear coat (they typically have UV protection)? Even on old card, I don't see issues with the plastic bumpers having issues with the sunlight.

[EEVblog]

For the switch, why not coat the box with a few layers of car paint and clear coat (they typically have UV protection)? Even on old card, I don't see issues with the plastic bumpers having issues with the sunlight.

Yep, didn't occur to me at the time, I assumed the box would be rated for long life UV

[Brumby]

I assumed the box would be rated for long life UV

As would any reasonable person.

To me, that choice of switch comes under the heading of "Not fit for purpose".

[Richard Crowley]

Just putting tape over the joint around the box may not do a lot of good.  It could even make it worse by trapping water between the tape and the box.  I would rather consider running a bead of RTV around the lip (in addition to that black rubber (?) seal.  RTV makes a good seal and is "re-enterable" by simply cutting it open with a knife if you need to get back into the box.

[Dundarave]

There looks like there may be room to mount the new switch under the panel array instead of on its edge?

That would both shield it from the sun as well as protect it from direct rainfall.

[coppercone2]

how much is that fault going to take to pay off? how many sunlight hours did that set you back?

bad chassis makes me sad

[eV1Te]

I would replace the isolator switch on the wall as well if it is of the same model. Clearly not made for outdoor use if the plastic degrades after only 6 years.

Considering that a switch is mechanical it must be difficult to guarantee good weathersealing around the knob itself. Better to use a box where the knob is under a sealed lid/door I guess.

[Whales]

Dave: I believe the second isolation switch on the roof is a common standard. 

In the AC distribution industry: it's common for lineworkers not to trust any pole-mounted disconnect (ie levers on the side of poles) or over-head-wire grounding clamps unless they can actually see them.  Too many situations where someone has fiddled with them whilst they are working, or thought they were done with the job.  I suspect it's the same when solar workers are on the roof: if you can't see the isolator, then it doesn't exist, and/or the customer has forgotten about you and is trying to get their aircon going again.

Exact scenarios where a DC disconnector up on the roof would help: not sure, other than perhaps back-feeding to the panels?  Otherwise it's just as dangerous up there with or without the isolator, given that the panels are the source?  Perhaps moving the feed from the roof to somewhere else in the house is expected, eg when people later change their systems to use big batteries.

[mikeselectricstuff]

I always use diecast aluminium IP68 boxes for anything outdoor. It's the only way to be sure.
And what's with "get it replaced" - why aren't you doing it yourself ?

[capt bullshot]

Both isolator switches look pretty pointless to me.
The Sunny Boy inverter has an internal DC isolator (the pull tab at the bottom left of it) - here in Germany this is considered safe enough, for sure it passed various certifications, so no extra switch gets installed.
And for isolating the AC side, the Sunny Boy also has a total for four N/O single pole internal relays (each two of them in series for Neutral and Live) to safely disconnect the Inverter and Panels from the AC in case of e.g. ground failure (yes, there's also an internal ground fault monitor).
So except for breaking local rules, you're totally safe if you bypass the DC isolator switches.

[mikeselectricstuff]

The only reason I can see for a switch up top is that it removes any ground reference, so assuming there aren't any shorts or leakage, you can safely touch any single point in the string, so for example if you discover some panel damage you can investigate without having to go down, or unplug any inter-panel connectors. 

[ogden]

I always use diecast aluminium IP68 boxes for anything outdoor. It's the only way to be sure.

In such case your equipment is protected not only against UV but micrometeorites as well 

[capt bullshot]

Exact scenarios where a DC disconnector up on the roof would help: not sure, other than perhaps back-feeding to the panels?  Otherwise it's just as dangerous up there with or without the isolator, given that the panels are the source?  Perhaps moving the feed from the roof to somewhere else in the house is expected, eg when people later change their systems to use big batteries.

In Europe, there were / are discussions about roof or below the roof mounted DC isolators for solar systems, required by the fire brigade caring about the safety of the firemen. But these weren't poorly encapsulated switches like the one that failed, rather more sophisticated ones that break the DC automatically when the firemen disconnect the house from the AC supply (this is routinely done, and this is why normally a fuse / breaker box is accessible from outside your house).

[madires]

I'd place a piece of aluminium sheet or roof type board a few cm above the switch box for protection against direct sun and rain.

[Brumby]

And what's with "get it replaced" - why aren't you doing it yourself ?

If Dave isn't a licenced electrician with the training for solar work, it will be illegal for him to touch it.  Opening the cover as he did was nudging the line.

[dcac]

And what's with "get it replaced" - why aren't you doing it yourself ?

If Dave isn't a licenced electrician with the training for solar work, it will be illegal for him to touch it.  Opening the cover as he did was nudging the line.

You’d think on the solar panel side of the installation you could troubleshoot and replace component as long as you know what you are doing. On the grid side though I can understand DIY work isn’t allowed.

[mikeselectricstuff]

And what's with "get it replaced" - why aren't you doing it yourself ?

If Dave isn't a licenced electrician with the training for solar work, it will be illegal for him to touch it.  Opening the cover as he did was nudging the line.

Who is ever going to find out ( assuming it's not on video)  ?

[maelli]

No extra DC disconnecter required in Switzerland, not on the roof, not near the inverter.
I do have a Fronius Symo.

I am not planning to walk on my roof for the next 25 years, would not be easy in my case.

What is required here is a connector box with heavy overvoltage protection MOVs, 1000V, guess this is for lightning protection.
This box is also in the basement, where the DC enters the house.

[HKJ]

If Dave isn't a licenced electrician with the training for solar work, it will be illegal for him to touch it.  Opening the cover as he did was nudging the line.

These rules are very country specific, with your being based in Australia I suppose you are post is based on the rules that apply to Dave.

[mikeselectricstuff]

If Dave isn't a licenced electrician with the training for solar work, it will be illegal for him to touch it.  Opening the cover as he did was nudging the line.

These rules are very country specific, with your being based in Australia I suppose you are post is based on the rules that apply to Dave.

Australia has some of the stupidest rules on electrical work, which even extend to plug-in appliances, AIUI they arose out of the unions wanting a closed shop and little to do with actual safety.
But for a simple like-for-like replacement such as this, who's gonna know if it was even done, let alone who did it?

[NivagSwerdna]

@5:22   

[Monkeh]

And what's with "get it replaced" - why aren't you doing it yourself ?

I've gathered over the years that Dave is not fond of playing with electricity at voltages capable of harm.

[free_electron]

who mounts that thing unprotected ? at least mount it UNDER the panels...

[thm_w]

Who is ever going to find out ( assuming it's not on video)  ?

Well thats the point right, say "I'll get someone to do it" then do it yourself.
If Dave said publicly at any point that he is performing electrical work it could theoretically be used against him. ie manufacturer could void the panel or inverter warranty, household insurance can be void if his house burns down and its found to be from solar wiring, etc.

[jnissen]

That is one crusty switch and enclosure. Surprised they allow plastic boxes or enclosures at all. I used micro-inverters so there is no DC disconnect switches. The DC to AC disconnect is built into the inverter (likely already built into yours as well). Since I have AC exiting the system then all boxes and switches are in metal code compliant boxes. No issue with UV and water in that case.

[CatalinaWOW]

I'm actually stunned by Dave's low expectations.  He seems to think it is normal for a "weatherproof" box to fail after a few years, and doesn't seem too hopeful that the rest of his system will survive much longer than a decade.

[floobydust]

The better outdoor electrical enclosures are fiberglass-reinforced polyester. But direct sun UV and heat will still degrade the material, they don't last forever.
Polycarbonate is cheap and terrible in the sun and cracks and yellows. Dave's enclosure failed on a thin web along the gasket cutout, so expansion and contraction there.

I think it's a really dangerous failure. Leakage currents to anything nearby due to moisture, rust, electrolysis. At least it didn't arc and carbon track.

Are these solar arrays floating going into the inverter?  Solar panel ground-fault detection would be useful.

[Brumby]

Australia has some of the stupidest rules on electrical work, which even extend to plug-in appliances

As far as I'm aware, the electrician licencing requirement relates to fixed wiring only.

[mikeselectricstuff]

Australia has some of the stupidest rules on electrical work, which even extend to plug-in appliances

As far as I'm aware, the electrician licencing requirement relates to fixed wiring only.

I think this varies by state - I saw a vid a while ago by an Aus YTer who said that portable devices were covered in some states. There was also recently a news story about an Aus electronics magazine getting hassle from the licensing authoraties for publishing mains-powered projects.

[EEVblog]

I'm actually stunned by Dave's low expectations.  He seems to think it is normal for a "weatherproof" box to fail after a few years, and doesn't seem too hopeful that the rest of his system will survive much longer than a decade.

I meant at least a decade out of it before trouble. With 12 panels the likelihood that one fails in some way after a decade is certainly non-zero. And throw in Murphy.
And it's not "a few years", it's 6 years under the notoriously harsh Australian sun.
Even this top quality aussie made one designed for our conditions comes standard with a protective cover:
http://www.cobaltsolar.com.au/COBALTBLACK_DC
So, no, not really surprising the UV killed an exposed plastic one, common as mud failure.

[ogden]

So, no, not really surprising the UV killed an exposed plastic one, common as mud failure.

Hopefully you will do something about it - make sure that switch is installed in metallic all weather enclosure perhaps? Failure mode of those disintegrating plastic boxes collecting water inside (w/o drain!) is real fire hazard. Luckily nothing happened    Perhaps many switch fire incidents reported were caused not by inferior switch but water ingress.

[EEVblog]

So, no, not really surprising the UV killed an exposed plastic one, common as mud failure.

Hopefully you will do something about it - make sure that switch is installed in metallic all weather enclosure perhaps? Failure mode of those disintegrating plastic boxes collecting water inside (w/o drain!) is real fire hazard. Luckily nothing happened    Perhaps many switch fire incidents reported were caused not by inferior switch but water ingress.

They come standard with a basic weather hood.

[floobydust]

That product has lovely marketing, but where are the product's agency safety approvals? The brochure has a TUV Rheinland logo, but nothing in their certification database. It's probably for the polycarbonate enclosure.

I though Australia would be strict about it, the reason for so many DC isolator recalls it seems is anybody can make and sell one. But they have a safety function.
They bitch against mains-powered projects in an electronics magazine but not this stuff?

DC isolator safety advice

[Andrew McNamara]

I though Australia would be strict about it, the reason for so many DC isolator recalls it seems is anybody can make and sell one. But they have a safety function.
They bitch against mains-powered projects in an electronics magazine but not this stuff?

Call me cynical, but most of the rules and regulations in Oz are about protecting vested interested, not the public.

[coppercone2]

that little hat is a stupid fucking idea, its like a bug house

lets make life easy for spiders and wasps

I hate high surface area not allowed to touch out door shit

[floobydust]

They don't seem to work, apparently the fire department's water nozzle hits at too high a pressure and water gets in the isolator anyway.
People hate climbing up there to switch them off to work on their inverters.
I saw a petition to get them off the roof, lost the url maybe SEIA sponsored it.

[madires]

Why not replacing the isolation switch on the roof with a contactor controlled from a location easy to reach? In case of a fire the PV system can be disabled quickly and safely. If the cable to the contactor is damaged everything will be disabled automatically (fail safe). The HV DC from PV panels is a real problem for firefighters. There are reports of buildings with PV panels being let burn down in a controlled manner because of the lack of a cut-off switch for the PV panels on the roof.

[Yansi]

funny to think that even a simple bit of electrical tape around the seam would have saved it.

It would not by any means.

[HackedFridgeMagnet]

As much as you guys like to bag Australian wiring rules.

The rules had it covered. (from ASNZS 5033:2014)

4.3.3 PV array and PV equipment
4.3.3.1 Environmental effects
All equipment exposed to the outdoor environment shall be at least IP 54 compliant in
accordance with AS 60529, and shall be UV resistant.
NOTE: Higher IP ratings should be considered for tropical regions.
All enclosures, including but not limited to junction, combiner and isolation devices that are
installed adjacent to the array and that could be affected by water jets associated with
cleaning of the array shall be a minimum of IP 55 compliant.
Any enclosure IP rating shall suit the environmental conditions. This IP rating shall apply
for the relevant mounting position.

I think the isolator box is probably ABS plastic. These apparently deteriorates more in UV light than poly-carbonate.
AFAIK the roof mounted isolator is so fire people can turn it off easily in an emergency. This rule came later and I guess after some incident where the fireys complained.
from the same standard:

4.4.1.5 PV switch-disconnector (Australia only) (NZ has a different rule here. )
In LV PV arrays in Australia, switch-disconnectors as specified in Table 4.3, shall be
installed adjacent to a PV array on the PV array cable or on multiple circuits according to
Clause 4.4.1.4, so as to provide safe disconnection of the array from the PCE (refer to
Figures 2.5, 2.6 and 4.4).
In cases where the PCE in LV systems is not in sight of the array or more than 3 m from the
array, switch-disconnectors shall also be installed adjacent to the PCE or within the PCE,
according to Clause 4.4.1.2. All PV switch-disconnectors shall be readily available.

PCE is power conversion equipment.

I think a small 3-4mm hole at the bottom is better than an imperfect seal. The seal in that situation can only be imperfect as the conduit is not sealed. Condensation can find it way in through the conduit.

Also I think a lot of the early recalled isolators were just AC isolators used for DC. The newer ones are actually approved for breaking DC. Maybe Dave can teardown the damaged DC isolator and see if it has some sort of arc suppression?

[Yansi]

Yes, I also second the box was cheap standard ABS.  I think polycarbonate is one of the more expensive plastics.

Well, looking into the disconnect in the Dave's video, I doubt it has any meaningful DC ratings, as it is even wired two contacts in series, which does not instill much confidence in me that it indeed was suited for DC. Such series wired contacts are commonplace where AC contactors/switches are repurposed for DC.  But it indeed might be... who knows.  I have never had any of these in hand to look at.

[SparkyFX]

Call me cynical, but most of the rules and regulations in Oz are about protecting vested interested, not the public.

Cynical! There is an associated topic, i guess the PV-arrays are galvanically isolated from ground (probably within the inverter), therefore regulations for mains operated equipment might not apply at all. It´s still high voltage DC.

They come standard with a basic weather hood.

Looks more promising, the black color at least indicates more soot (color) in the material, which blocks more UV and is more stable toward it. The hood prevents additional thermal stress on the housing vs. its screws (should they have a different thermal expansion coefficient than the plastics).

[Yansi]

Call me cynical, but most of the rules and regulations in Oz are about protecting vested interested, not the public.

Cynical! There is an associated topic, i guess the PV-arrays are galvanically isolated from ground (probably within the inverter), therefore regulations for mains operated equipment might not apply at all. It´s still high voltage DC.

50V is hardly high voltage. 

[SparkyFX]

But the panels are in series... read the system voltage on this plate.
.

Not "high voltage" as per definition (>1000VAC rms / >1500VDC), but hazardous, sorry should that have caused confusion.

[Yansi]

Sorry, I now see I wrote 50V instead of 500V. (Dave measured like 400something volts on the string in the video).
But  still, up to 1000V is considered low voltage.  I may seem picky, but really, its you Germans being picky

[EEVblog]

Yes, I also second the box was cheap standard ABS.  I think polycarbonate is one of the more expensive plastics.

Well, looking into the disconnect in the Dave's video, I doubt it has any meaningful DC ratings, as it is even wired two contacts in series, which does not instill much confidence in me that it indeed was suited for DC. Such series wired contacts are commonplace where AC contactors/switches are repurposed for DC.  But it indeed might be... who knows.  I have never had any of these in hand to look at.

For those interested, the isolator is a bendict LS25 PFLH4
http://www.celiss.com/products/files20177311641475463911978.pdf

[floobydust]

For those interested, the isolator is a bendict LS25 PFLH4
http://www.celiss.com/products/files20177311641475463911978.pdf

  Its got agency approvals UL/CSA! And temperature derating curves. It looks really good  - IF you can keep it dry.

edit: Is "NHP Benedict" some ripoff of the company's name?

[Poe]

how much is that fault going to take to pay off? how many sunlight hours did that set you back?

Exactly.

[SparkyFX]

500V/7A is not particulary hard for a switch - or two in series.

I wonder if they need to be mechanically timed (one advances the other) to improve the arc breaking or if slight dimensional differences alone are sufficient. I mean the spark gap doubles over two switches just because it is double the distance, but do resistance differences between arcs inhibit two arcs in series? As in one switch pulls an arc, therefore there is not enough breakdown voltage left for the other switch, or more current = more plasma/ionized gas = better conductivity = lower voltage drop per distance, like a current dependent resistor, should such a concept exist.

This might not be very relevant for a manual operated switch, but for contactors and such.

I think such breakers/isolators exist in in actual high voltage applications.
Although recently i´ve seen a fail with a standing arc for at least two minutes and grass fire from the molten metal.

[Krysole]

I stumbled on a strange piece by the ABC 7:30 report on solar systems in here in Australia. No idea why it got recommended to me, but no matter. It looked a little at panel failures, isolator switches and so on, although not in as much depth as they maybe could have. It was only for TV through, but still possibly worth a watch or read.

https://youtu.be/10Gnf-wvF7A
https://www.abc.net.au/news/2019-05-27/australias-obsession-with-cheap-solar-derailing-market-insiders/11139856

Apparently your not the only one having a bit of a problem with weather damage to the switches. Might have to have a quick look at the system on my roof at some point...hmm.

[wilfred]

There was an article on the ABC (Australia) news website about solar system fires today. It was about a DC Isolator on some lady's house.
https://www.abc.net.au/news/2023-09-14/solar-panel-fires-increase-dc-isolator-nt-worksafe-warning/102843552

We need Bigclive to do a video on why what appears to me to be a simple switch can fail so dramatically so often.

I looked at this video to see if Dave said anything relevant but he didn't see flames on his failure.

[EEVblog]

There was an article on the ABC (Australia) news website about solar system fires today. It was about a DC Isolator on some lady's house.
https://www.abc.net.au/news/2023-09-14/solar-panel-fires-increase-dc-isolator-nt-worksafe-warning/102843552
We need Bigclive to do a video on why what appears to me to be a simple switch can fail so dramatically so often.
I looked at this video to see if Dave said anything relevant but he didn't see flames on his failure.

It would have to be for not adequate arc quenching within the switch mechanism.
Might be fine under normal conditions, but get some water ingress and all bets are off.
IIRC there are like a dozen or so recalls of various models just in Australia.

[nctnico]

IMHO it is better to get an inverter with an internal DC switch and use (MC4) connectors to attach the wires to the inverter (I have such a model from Growatt). That way you don't need an external switch that is likely to be the cheapest rubbish the installer can buy.

[floobydust]

Australia removes much-criticized DC isolator mandate Nov. 2021 "Water entering DC isolators is identified as the greatest risk and the most common cause of PV system failures."

"Rooftop DC isolators and solar inverters were found to be the main causes in solar-related fires. From 2009 to 2015, between 38% and 50% of recorded solar-related fires in WA and NSW were caused by a DC isolator. Prior to 2015, the majority of solar-related fires in Queensland were associated with DC isolators."
https://renew.org.au/research/rooftop-dc-isolators-and-solar-system-fires/

Uh so without one... you're using a DC isolator located downstream (pun intended) somewhere dry instead?
I notice they have no safety certs or approvals, save a few bucks with the chinese specials but the heat+UV is brutal on fiberglass and plastics, they need a better housing arrangement. Maybe aluminum or SS box overtop?

[EEVblog]

Australia removes much-criticized DC isolator mandate Nov. 2021 "Water entering DC isolators is identified as the greatest risk and the most common cause of PV system failures."

"Rooftop DC isolators and solar inverters were found to be the main causes in solar-related fires. From 2009 to 2015, between 38% and 50% of recorded solar-related fires in WA and NSW were caused by a DC isolator. Prior to 2015, the majority of solar-related fires in Queensland were associated with DC isolators."
https://renew.org.au/research/rooftop-dc-isolators-and-solar-system-fires/

Uh so without one... you're using a DC isolator located downstream (pun intended) somewhere dry instead?

Yes, there is a 2nd one next to the inverter.
Still outside and subject to weather, but much less harsh than on the roof.
https://youtu.be/VGENVguQQmo?t=1252

[EEVblog]

Australia removes much-criticized DC isolator mandate Nov. 2021 "Water entering DC isolators is identified as the greatest risk and the most common cause of PV system failures."

I didn't know that, interesting.

[coppice]

Australia removes much-criticized DC isolator mandate Nov. 2021 "Water entering DC isolators is identified as the greatest risk and the most common cause of PV system failures."

"Rooftop DC isolators and solar inverters were found to be the main causes in solar-related fires. From 2009 to 2015, between 38% and 50% of recorded solar-related fires in WA and NSW were caused by a DC isolator. Prior to 2015, the majority of solar-related fires in Queensland were associated with DC isolators."
https://renew.org.au/research/rooftop-dc-isolators-and-solar-system-fires/

Uh so without one... you're using a DC isolator located downstream (pun intended) somewhere dry instead?
I notice they have no safety certs or approvals, save a few bucks with the chinese specials but the heat+UV is brutal on fiberglass and plastics, they need a better housing arrangement. Maybe aluminum or SS box overtop?

Interesting that they stopped requiring an isolator, rather than setting standards for something reliable.

[EEVblog]

Interesting that they stopped requiring an isolator, rather than setting standards for something reliable.

I'd like to see the actual standard. Perhaps they just mean the rooftop one?
My inverter also has an isolator tab atthe bottom of it, not sure if that's mandatory? I'd assume so, because NO isolator is at all is kinda nuts.
But in my case, three is too many.

[nctnico]

Having 3 switches is also nuts. It is just adding more points of failure. One of the pictures with the articles linked above showed a wall mounted DC switch (or what is left of it). So be sure to check your wall mounted switch as well.

And what does the code actually require? Over here there is much confusion over needing an AC safety switch next to the PV interter. The code actually says a seperator switch is required to disconnect the PV inverter from the grid without a specification where that switch needs to be mounted. A dual pole breaker in the fuse counts as a seperator switch. A safety switch is to switch off machinery with moving / rotating parts which doesn't apply to a PV inverter. Needless to say I didn't install the AC safety switch next to my PV inverter. As an extra AC switch is just another part that can go bad.

[floobydust]

I vaguely remember the rooftop isolator requirement was for fire crews wanting safety when fire fighting and pouring water on the roof.
Of the two energy sources (solar and mains), local disconnects at both. They'll let it burn until the isolator and mains disconnect have been switched off.

But I'm not confident with earth-grounded frames and rails and loads of water, that a fire fighter wouldn't get a several hundred V wallop through the water stream/fire hose, including that it can run to the (floating) pumper truck. This is with a series string. I imagine a ground-fault is possible with things burning up.
So far solar electrical standards seem a little torn between low cost and dealing with reality.

[nctnico]

Water sprayed from a fire hose doesn't conduct after a few meters.