[RE-wrenches] Just saw this and thought it worth sharing

[Jason Szumlanski]

Here is Enphase's answer (or maybe Fronius was answering Enphase):

https://enphase.com/en-us/support/arc-fault-demonstration

Also, their literature suggests that the risk of a DC arc fault occuring is
far lower due to there being much less DC cabling exposed on the roof. With
no long DC home runs, that would obviously lower the probability of an
occurrence. I see where they are coming from, but we're talking about
severity here, not probability.

I have seen a few melted MC4 connectors at the panel to microinverter
connection. The results seem to support Enphase's video where the arc is
small and possibly intermittent, melting a hole in the connector housing,
but falling short of an exposed flame.

I think there is a twofold response that a microinverter manufacturer would
make. The probability of DC Arc fault is reduced and severity is lower.
That's a strong argument.

Is anyone aware of a significant fire in a microinverter system caused by a
DC arc fault? I assume there are anecdotes out there, but I haven't heard
of any. On the flip side, I've seen some pretty gnarled DC conductor
bundles melted together on string inverter systems with burned modules
above them.

That said, I would probably support more safety on the DC side of
microinverters. If AC modules weren't so darn expensive, I'd probably go
that direction. If PV DC leads were shorter I'd probably mount
microinverters to module frames. If integrated AFCI was available on
microinverters at a reasonable cost, that would be great.

Jason Szumlanski
Florida Solar Design Group


On Fri, Feb 5, 2021, 5:40 PM Jeremy Coxon <jcoxon at sunwindpowerinc.com>
wrote:

> Very interesting video, now I know Fronius is pointing fingers at Micro
> manufacturers but the demo seems to back up their proposal to scrap the 80V
> limit.  This is yet another reason we haven’t used many Micro’s on our
> systems.
>
> https://m.youtube.com/watch?v=H3c9GbLhQhY&t=4s
>
>
> Jeremy Coxon NABCEP
> Certified MWBE
>
> Sent from my iPhone
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