Solar GFDI to prevent fires

[gklott]

Am seeing more Escape trailers adding solar arrays beyond the 2-panel ETI option (two GP BF-190M, Voc=24.09, Isc=9.98A).

Specifically, I see many RV, not just ETI trailers, that add a third or fourth panel. We likely have seen Johnny Hung's system, with 8-panels on the roof.

RVIA and QAI (Canada) specify following the National Electric Code (NEC - NFPA 70) in all RVs. Most RV insurance companies require owners to comply with standards and industry best practice on modifications that effect RV safety. Yet, other than an OEM wanting RVIA or QAI certification, many installations to not follow these standards.

The 2017 National Electric Code (and 2020,2023 editions) has this requirement: "§690.41.(B). Ground-fault protection. PV DC circuits that exceed 30V or 8 amperes shall be provided with dc ground fault detection meeting the requirements of 690.41(B)(1) and (B)(2) to reduce fire hazards.
Solidly grounded PV source circuits with not more than two modules in parallel and not on or in buildings shall be permitted without ground fault protection."

The ETI system OEM configuration has two modules in parallel. The charge controller (GoPower and Victron) provide grounding between the - PV terminal, - battery terminal, and chassis. This meets the RVIA and QAI requirements.

In our E19 and in our daughter's E21NE, I added a 30A MaxiFuse and disconnect switch before the solar charge controller. I also added a 50A MaxiFuse between the charge controller and the + main bus. I upgraded the wiring accordingly.

Are companies that add a third or more panels to ETI trailers complying with the GFDI requirement? Have you added this GFDI if expanding beyond the two panel configuration?

73/gus

[Centex]

So Gus, as you read the referenced codes would a GFPD be required at all three 'levels' (L1, L2, L3) in the array with 3 or more paralleled PV Panels depicted in the the crude single-line diagram attached?

[gklott]

Originally Posted by Centex

So Gus, according to the referenced codes would a GFPD be required at all three 'levels' in the array with 3 or more PV Panels depicted in the the crude single-line diagram attached?

(1) Do the PV DC circuits exceed 30V or 8 amperes? Your labeling indicates yes.

(2) Does your PV bus combiner have overcurrent protection? See NEC §690.9. l'd recommend using a fused combiner box. I have also seen several RVers use the MC4 inline fuse holders.

Then turn to §690.41(B)(2): "The faulted circuits shall be controlled by one of the following methods:
(1) The current-carrying conductors of the faulted circuit shall be automatically disconnected.
(2)The device providing ground fault protection fed by the faulted circuit shall automatically cease to supply power to output circuits and interrupt the faulted PV system dc circuits from the ground reference in a functionally grounded system."

Without knowing all the details in your "crude single-line diagram", L2 seems the correct location. You need to determine the correct positioning given all your system details.

Victron, Midnite Solar, Morningstar, and others have excellent application notes on using PV GFPD. Recommend consulting them with your details.

73/gus

[John in Santa Cruz]

huh. my single 360W panel is around 10 amps at 36 volts, so ti exceeds both of those parameters.

OTOH, nothing PV is grounded. PV + and PV - both go directly to a Victron 100/30. The Battery - is grounded, of course.

[gklott]

Originally Posted by John in Santa Cruz

huh. my single 360W panel is around 10 amps at 36 volts, so ti exceeds both of those parameters.
OTOH, nothing PV is grounded. PV + and PV - both go directly to a Victron 100/30. The Battery - is grounded, of course.

You only have one panel, so the exception seems to apply as long as you have "solidly grounded PV source circuits".

My two solar panels are in parallel, and the combined conductors are also ungrounded until they reach the Victron controller. My solar disconnect switch is for both the + and - PV wires.

My Victron 100/50 MPPT controller has a negative (-) for solar input and negative (-) charger output. Checking these two with an ohm meter, these two are connected, solidly grounding the PV source circuits.

Our Victron MPPT 100/30 and 100/50 on-line manual §4.4 says: "Ground fault detection.
The solar charger does not have internal ground fault protection. The USA National Electrical Code (NEC) requires the use of an external ground fault protection device (GFPD). The system electrical negative should be bonded through a GFPD to earth ground at one (and only one) location."

All our trailers should have the negative battery, AC mains grounding conductor (green wire), and physical chassis all interconnected.

73/gus