But I also see carbon tracking on a panel's back sheet. The cells must get overloaded during a mid-array ground fault and melt the back sheet?
I meant to say there are pictures of connectors that look like MC4. I can't (yet) tell the difference between the real MC4 and something similar. Before this thread started I thought any connector of that style was a MC4 and could just plug in to any mating connector. This thread has been a real eye opener about solar specific connectors, proper installation, and fires.
... lets not forget the arc is just the effect of something breaking that was not supposed to break.
Amphenol is very heavily into their RADSOK (RADial SOcKet) spring-contact technology, to get 52A ratings on H4.
I wonder if it actually ages well or if manufacturing QC is good enough for the "hyperbolic mesh"? It does not look easy to make/assemble in a pin. No mention of the metals used and I would suspect the connection between the two sleeves does not last.
Another overlooked aspect for DC connections is ion migration at the connection, the connection's metallurgy changes with age, it does oxidize/corrode more than AC. I would guess tin migrates away. That would be seen as a polarity issue for the failures, they might favour a cathode end.
I've got MC4 panels and MC4 inverters that were produced before H4 and alternatives became popular. However, if I had gotten one or the other in H4 and the spec sheet said "MC4 compatible" I would have plugged them in without a second thought--but I'd be thinking about it now! Everyone with a DC system and mixed or unknown connectors ought to be taking a look at this point.
If these installations worked flawlessly several years before failure they most likely had been under peak load several times, but something changed/wore out and made it fail catastrophically.
I could find no data from other PV connector manufacturers on deratings.
Why can't they just make these connectors a bit bigger and give them true current ratings?
Weidmuller has PV-Stick push in (no crimp) the bare wire type of connector, rated 30A. I wonder what magic is inside.
PV-Stick push in (no crimp) the bare wire type of connector, rated 30A. I wonder what magic is inside.
Wow, these MC4 connectors have a serious thermal de-rating! Thanks to Stäubli for giving us some data, and saying "don't mix and match" with other connectors.
I'm not sure what typical rooftop temperatures are, but the rated amperage is to 30C and I would cut it in half. Bet people aren't doing that and then add a Y to double input current.
I could find no data from other PV connector manufacturers on deratings.
...
Why can't they just make these connectors a bit bigger and give them true current ratings?
each string is connected to a combiner box by a real electrician using real wiring and then that electrician does the balance of the wiring, again with real, enclosed-in-conduit wiring. I guess I'm hopelessly out of touch.
each string is connected to a combiner box by a real electrician using real wiring and then that electrician does the balance of the wiring, again with real, enclosed-in-conduit wiring. I guess I'm hopelessly out of touch.
I wonder what magic is inside.
each string is connected to a combiner box by a real electrician using real wiring and then that electrician does the balance of the wiring, again with real, enclosed-in-conduit wiring. I guess I'm hopelessly out of touch.
It's a good point, commercial buildings require all (mains) wiring must be enclosed in conduit. Rooftop air conditioners are wired this way.
I wonder why the NFPA allows loose wires and zip ties for solar systems.
With all the BS OSHA safety crap is around arc flash hazards today, I'm bewildered how a connector like this can be rated for 1KV @ 30A without requiring permanently embossed warnings, high viz colors and LOTO provisions. 1kv AC has an absolute $hitload of safety requirements at any moderate power level. Internally in a building, your going to have to accommodate that with special construction in most cases.
Opening that live is going to be exciting I expect.
I'm bewildered how a connector like this can be rated for 1KV @ 30A without requiring permanently embossed warnings, high viz colors and LOTO provisions
Been a while since I was up on NEC code here. When I was...
Class 2 is 50v & 100va and under, no conduit required in most cases. Above that is class 1 and requires "conduit" of some fashion generally.
They are built to snap in and "require a tool" to be opened again. No idea if that actually makes them safer, but at least someone thought of that.
LOTO probably starts on the DC isolator switch. The thing to remember is... danger is highest when the sun shines, it´s a generator after all.