eevBLAB #64 - Tesla Solar Panels Are CATCHING ON FIRE!

[orion242]

Another stupid question, why don't solar panels come standard with a peel off cover? Given how frequent high voltage strings are used it would seem a convenient protection.

What does this really accomplish, protecting the installing crew from HV?  With the inverter disconnected, everything dry, shouldn't be a huge hazard. They could just leave the panels in a string disconnected till that string is ready and stab these connectors together under no load.  Walk down the string and stab together in 5min or piss around pulling this off every panel and disposing.  Labor cost vs safety improvement, non-starter I assume.

How the hell you shut it off later in life without disconnects per panel, seems a bit more fiddly.  Its high noon, your crap is arching / on fire single or few panels and need to stop everything in that string...now what?

I can't wait to check out a commercial install.  Want to see how they deal with these strings, the connectors, wiring, disconnects / combiners, etc, etc.  Do they put the connectors up high under the panels with drip loops or lay them on roof?  Where is the fusing and disconnects? What are the ratings on the fusing / disconnects.  Ground fault protection?  Grounding of the install in general?  And on and on and on.  Not grounded, fine...but if the village idiot can open 1kv 30A connector by hand, your body could be completing that circuit when the arc starts grounded or not.  That mistake likely only happens once.

I might break down and ask for tour and take a vaca day if I don't end up back there soon.  Will be snapping plenty of photos and unless its a total horror show, will share.

[tautech]

I can't wait to check out a commercial install.  Want to see how they deal with these strings, the connectors, wiring, disconnects / combiners, etc, etc.  Do they put the connectors up high under the panels with drip loops or lay them on roof?  Where is the fusing and disconnects? What are the ratings on the fusing / disconnects.  Ground fault protection?  Grounding of the install in general?  And on and on and on.

I might break down and ask for tour and take a vaca day if I don't end up back there soon.

I think for the competent handyman a PV installation is not too difficult or challenging especially if the PV string voltage is not too high.
A small array I've done recently using just three 300W panels we looked at different panel orientations to enhance weather tightness but the panel lead boxes though rated IP68 looked like they'd be best at the top of the panel so their leads exit lower down....common sense.
Explicitly their interconnects are labeled as NOT to disconnect or connect under load and each panel had several points marked as suitable for earths or strapping points.
As for the interconnects on these panels I think they were some copy of ones described earlier in this thread however common sense would have one cable tying them out of the weather and out of harms way like puddles should they be installed flat.
One thing I have picked up from this thread is the heat issue under the panels that might impact on connector reliability so we strapped them onto the inside of the alloy frame where they might be better.
Drip loops should always be considered and where we could we incorporated them....again, common sense.

I too would like to inspect a commercial installation so when next at our sons place in Perth I'll have a look at his new 21 panel installation with the view to learning something....or not ! 

[orion242]

A lot of mechanical engineering seems to have gone into the panel's mounting struts and extrusions, with no thought about the wiring, just use low cost tie-wraps that age and easily break. A simple cable-tray might be better and could be part of the extrusions as a U-channel, to keep the connectors and wiring from laying on the roof.

I suspect this is a big part of the problem when you expect to use low skilled labor to slap them in.  The panel racking should have provisions for this that make it harder to do a piss poor job.  Sure you cannot prevent total hacks, but you can make things easy enough it only the bottom feeders that do otherwise.

You have the panels themselves which are waterproof and block UV.  Ice, UV and a lot of BS should be easily avoided if these connectors have a convenient spot behind the center of the panel to attach them such that they are the highest point the in cabling.  The rest of the racking should have wire chases in mind for interconnection between panels and whatever combiner / disconnect requirements there are.

[orion242]

I think for the competent handyman a PV installation is not too difficult or challenging especially if the PV string voltage is not too high.

Ditto.  My shed is solar and at that and even modest home, the power levels are a nothing burger.  I'm thinking commercial installs,  well in excess of 100 panels.  Wallyworld isn't putting a few kwh of panels on their roof.

Explicitly their interconnects are labeled as NOT to disconnect or connect under load and each panel had several points marked as suitable for earths or strapping points.

For starters, its almost designed to be easily disconnected by hand.  An idiot would likely just find it natural to pull them apart by hand.  That alone is a design fail for something rated at this power level IMO.

Second, if you do not have a way for someone above the village idiot to use properly rated disconnects to make this safe in all conditions, another fail.

If the general install practice is to leave these connectors on the roof or in low points...not really a connector specific issue but another likely fail.

[tautech]

Explicitly their interconnects are labeled as NOT to disconnect or connect under load and each panel had several points marked as suitable for earths or strapping points.

For starters, its almost designed to be easily disconnected by hand.  An idiot would likely just find it natural to pull them apart by hand.  That alone is a design fail for something rated at this power level IMO.

Not so much as you might think.
The interconnects on the panels we used clip together and won't just pull apart so when inspecting them closely to find how they might disconnect the warnings are plainly visible.

[orion242]

The panels I have and the connectors under this thread I ordered sample of....

Village idiot would naturally walk up and disconnect by hand.  It seems ergonomically designed for simple hand disconnect.

For that matter, inspecting these connectors if being used at anything near their ratings seems questionable.  Let the village idiot pull them from a pool of water and inspect?

[tautech]

The panels I have and the connectors under this thread I ordered sample of....

Village idiot would naturally walk up and disconnect by hand.  It seems ergonomically designed for simple hand disconnect.

Ones here are different and you need a tool or say long nose pliers to squeeze the retaining clips in to allow separation.

[orion242]

We will have to differ on that point.  Maybe your area uses something completely different.

I have a sample of the connectors and will post a video on how hard it is.  These things look no different than the "MC4" crap I have on my own panels.  Tool required my arse.  Its a perfect setup.  One hand to depress the tabs with another hand to pull the opposite end out.  Insert body to circuit here...

[orion242]

Correction, I have a sample of the push on wire connectors for solar.  These are not UL listed so doubt they are even legal to use here.  Its the same format still.

I have little doubt they will mate with my panels just as easy to hand disconnect.  Will check and report back.

[orion242]

Made it up to the roof of a local solar install.  Been drizzle for the last two days, so everything is soaking wet.  Didn't spend a lot of time and sure wasn't going to be poking around in that weather.

Looks like a pretty clean install.  I couldn't find any major faults.  The panels are just above the roof, bolted to metal racking.  There is a slight tilt to them, but 3-5" off the roofing material.  All the wiring is under the panels, didn't spot any of it laying on the roof.  Where its connecting between rows, the wiring is in a split loom and neatly tied to the racking.



Where there is an interconnection between panels of any distance, its in EMT conduit.  Looked like the ends of all these runs have a bonding bushing with a 12AWG wire tied to the racking.




There must be a fair number of panels grouped together with a single disconnect.  Didn't count them all, but there was probably half dozen of these disconnects connecting these groups to the main wiring feeding to the inverters.  This main wiring is in a metal trough winding through the install.  Sun doesn't look to be doing that plastic disconnect handle much good.  Install is ~6yr old.



Only real damage I could see was some of the covers on the wiring trough was bent up.  Not sure how that happened.  Hard to imagine water getting trapped in and freezing causing that.



The number of disconnects seems pretty sparse for this many panels.  Guessing if a group of panels decide to go up, your letting the fire department deal with it.  Access isn't that great with all the panels, wiring and gas lines running all over.

If its dry next time I'm out there will have to see if I can see how things are ran under the panels.  Suspect its pretty neat and tidy.

[nctnico]

Only real damage I could see was some of the covers on the wiring trough was bent up.  Not sure how that happened.  Hard to imagine water getting trapped in and freezing causing that.

Probably thermal cycling. I've seen that before on similar cable ducts which run in a long section without room for shrinking/extending.

[orion242]

Almost has to be.  Strange thing is that's the shortest run of the main feeds.  You can see a 90deg turn in the photo.  Just off the opposite end of the photo is where it transferred in to what look like at 3x conduits 2" or greater into the building.  The trough was not physically connected to the conduit.  There are runs 3-4x that length without any damage.

Whatever, its minor.  This install isn't anything that wally world describes.

What voltages and power levels its running at, TBD.  What I call disconnects seem to also be the combiners.  Going to try and find the installers as-builts if they exist.  Will be digging deeper to see if I can see how the panels are connected and how everything is connected.  The install looks pretty clean.   Servicing panels looks like a nightmare.  Not sure the owner has any documentation on how to make anything safe.  There are only a few narrow paths to the back of the roof full of trip hazards, least unless your solar city and walk on the panels.

Only complaint, WFT does anyone do to eliminate or seriously reduce the hazard in the event of an emergency?  Its hopeless to have any idea what your disconnecting up there.  Bit of searching on those disconnects didn't produce warm and fuzzies.  That company seems to have removed all pages related to that arm of their company.

[floobydust]

It looks nice but then I cringed. Are these loose wires?
I would let the camera look underneath the panels, where the drama is. How the wiring gets into the conduit is likely to be... interesting because these installations are a mix of commercial building electrical code, and low voltage DC practices.

[orion242]

It looks nice but then I cringed. Are these loose wires?
I would let the camera look underneath the panels, where the drama is. How the wiring gets into the conduit is likely to be... interesting because these installations are a mix of commercial building electrical code, and low voltage DC practices.

As I said everything was soaking wet.  At my age, I'm not touching anything that could put me at a disadvantage.  Dripping and standing in water = avoiding hazardous voltages even practicing safety 3rd.  Could not see much under panels unless I wanted to lay on the wet roof.  What I did see, looked well installed.  Will be back when the weather is more reasonable to get pictures under the panels, inside the disconnects along with some voltage measurements of the feed in and main wiring.  Just not going that deep soaking wet   Disconnects seem to be rated 1kv 400A.  Things get pretty exciting at that level and they just feed the main wiring.

[floobydust]

I would not go near that disconnect enclosure as it very likely has water getting in because the one conduit hub/fitting is a bodge, and the handle may not be sealing after all that UV and heat. This means HV boots and gloves, and if you do open it, let it air out and dry before poking around. Condensation can also get inside.

A big problem with rigid conduit is the popular fittings don't seal and are not waterproof. Proper weatherproof fittings cost a lot more money and most electricians forget a gasket or bodge together something that doesn't really seal over the long term.
Second big problem with rigid conduit is Code considers it a ground conductor, so no dedicated ground wire is needed. I wonder how that was dealt with in the fiberglass enclosure... ground bushings are needed there. Maybe it was done right but I trust nothing until I've seen how it was done.

[SilverSolder]

[...]  Maybe it was done right but I trust nothing until I've seen how it was done.

Distrust, but verify!

[orion242]

I would not go near that disconnect enclosure as it very likely has water getting in because the one conduit hub/fitting is a bodge, and the handle may not be sealing after all that UV and heat.

That conduit fitting meets code.  Granted I share you opinion its not water proof, but there is nothing I see that wouldn't pass inspection.   PCV conduit solvent welded in the dessert will have water in it.  That enclosure should have holes in the back to drain water.  Its inches off the roof so that's still something to think about.  If it is collecting water to a point its in contact with anything live, its going to die in short order.  That could be the moment the cover is opened.

Checking they bonded the ground thru that plastic enclosure is a quick test, really not the main issue I would have opening it.  The contact hazard is nill unless you want to hold the conduit while poking around inside.

Opening the disconnect and it fails..arching over in your face.

Bypassing the door latch and the metal connection between the plastic handle & disconnect falling in the wrong spot.

Biggest hazards IMO.

Normally an AC guy and these issues are present when working with high fault current devices.  Shock hazard minor vs things blowing up in your face if your not aware of what can go wrong.  These days you need a space suit to do this kind of work OSHA compliant.  IMO that's only trying to prevent fools from hurting themselves while making it nearly impossible to preform the work required.

[SilverSolder]

[...] These days you need a space suit to do this kind of work OSHA compliant.  IMO that's only trying to prevent fools from hurting themselves while making it nearly impossible to preform the work required.

The rules are there for a reason!

[Brumby]

^^^   Luke Skywalker I   ^^^

[orion242]

The rules are there for a reason!

Agree.  Its to prevent any problems 100% without any consideration on the impact of actually preforming the work or the IQ/training of the people performing said work.  Loss of dexterity causing more cases that require that level of protection, not part of equation.  Its got to be safe enough for anyone capable of holding a screwdriver.

Let just look at this install.  Where is the fault current rating listed on this disconnect?  Can't touch it without a full system evaluation by PE if its not listed unless it can be powered down.  Open the disconnect...everything is still powered in most all cases.  In this case, the handle could likely break off due to UV before the disconnect opens.  Even opening the disconnect doesn't improve the safety factor with in this enclosure.  This is part of where I think the code hasn't caught up with reality.

Have the space suit in the car.  Expires more often than I use it typically.  I rarely see other sparkies wearing it either unless they suspect the equipment is total junk or the site is willing to swallow the costs without question.  The number of sites with arc flash ratings listed everywhere is almost nill.  Even new construction this is rare from what I see.

Would watch modern hi-rise, hasn't changed all that much IMO.  Sure the steel guys wear a harness for effect.  Note the 100% tie off use and 15-20' below platform/netting they are supposed to land on if they do fall.  From what I see, the fines have become a cost of doing business coupled with the fact they seem to know prior when OSHA is coming.