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motorhomer asked

DC ground fault protection

Hi guys. I am starting my new off grid solar setup and wanting to discuss safety with respect to DC grounding the array and MPPT.

I am using all Victron MPPT and separate inverter. I understand the requirements for DC grounding but within the USA there is a requirement for a ground fault fuse on the DC ground loop within the inverter.

Now I do not believe Victron has this built in as it will have to disconnect inputs and outputs if a current was detected on the DC ground loop.

So, I am wondering if its something I will install. I am not in USA so not needing to worry about the regulations there, but I do see a good reason for this GFP fuse as we do the same on out DC systems at work, disconnect ground if there is a DC current detected on the ground.

I was thinking a 1A DC MCB would be good but if a fault occurred, I would need to find a way to disconnect the PV from the MPPT. I could use a DC current detector and use a contactor to disconnect if greater than 1A was present.

This seems to be a good protection against a DC ground fault which could potentially cause a solar overheat and fire

What do you think, diagram of the US system attachedgfp.png

Grounding
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1 Answer
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motorhomer answered ·

After reading this artical it would be very easy to use a 1A DC MCB which is physically connected to two DC MCBs so they all trip out if a DC current was detected on the ground loop. The two additional MCB's will disconnect the array from the MPPT, only issue is will a 1A MCB be strong enough to operate several other MCB's on a large system?

http://www.solarabcs.org/about/publications/meeting_presentations_minutes/2011/02/pdfs/Arc-Code_History_PV_GFCIs.pdf

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