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