EEVblog #1217 - My Home Solar Power System FAILED!

[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.