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GFPD confusion

rhino

Solar Wizard
Joined
Jun 6, 2020
Messages
2,553
Location
Minnesota
There seems to be a lot of confusion (at least by me :) ) when a ground fault protection device is needed in a grounded PV installation in North America. I "thought" that all PV arrays in stationary/residential installation must have a GFPD connected to it in order to detect when a ground fault occurs. Some charge controllers have this built-in such as the Midnite Solar Classic. If this is required for all PV arrays then why isn't all charge controllers sold in North America have them built-in? Are manufacturers that don't have this built-in assuming the installer just tacks on the additional cost of adding one?

I know of two readily available external GFPD. The Outback Power Ground Fault detection devices or the Morningstar Ground Fault protection device. The Outback is anywhere from $70 - $130 depending on number of arrays you need to cover whereas the Morningstar is over $300 for their 600V version per array. The Outback one seems a bit troubling since you are required to route all grounding connections including the battery ground through this device so that if a fault occurs your entire system becomes ungrounded. The Morningstar one does not do this and keeps your DC bus grounded.

My basic question is is this even required if your array is top of pole mounted and 100ft+ away from your residence?

Are inspectors requiring people to install these even if the array it not on your roof and your charge controller doesn't have this built-in?

I realize a lot (most?) of the "all-in-one" systems have the GFPD built-in as well.. so advantage to them for not having to think about this.
 
Well lots of variables let's start with:
(I believe)
There is an exception within NEC 690.41(B) to dc ground-fault protection:

Exception: PV arrays with not more than two PV source circuits and with all PV system dc circuits not on or in buildings shall be permitted without ground-fault protection where solidly grounded.

Does this help; does this answer your basic question?
 
@mopat I think that does help! I would have an array with 10 panels, 5 in series and parallel the two strings in combiner box with single set of cables going back to the charge controller. So that would fall under that exception rule, correct?
 
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