EEVblog #1217 - My Home Solar Power System FAILED!

[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?