Trailer Electrical Ground/Frame and Solar

[brulaz]

The negative terminal of the battery goes to the frame via 6ga wire.
And I think the AC ground goes to the frame when we're not off-grid.

I'll wire the MPPT controller with two 6ga wires going to the battery, or maybe the negative wire will stop at the frame as that's closer.

But the MPPT controller also has a "ground" terminal. Should I do something with that? I haven't run a ground wire from my solar frames either.

Rogue says to run a separate 10ga from the MPPT grd terminal to "a common location in the DC load center, and through a Ground Fault Protection Device (GFPD), to comply with NEC requirements".

What sort of GFPD are people using if anything? Could I just connect the grd to the neg wire in the load center? Or should i just ignore the Mppt grd terminal?

[dbertheau]

I think that installing a GFPD should be considered... Ground-fault protection is not just for residential roofs anymore. The 2008 NEC, for example, requires ground-fault protection for all “grounded dc photovoltaic arrays.” The seminal event that prompted this change was a ground fault that melted through the side of metal conduit on a medium sized commercial system. Even if one interprets that the code does not apply to our campers, $50 dollars for additional fire safety seems like good sense.

[westend]

BoonHauler wrote:
Here's what the manual states:

Rogue Manual wrote:
11.3 Grounding
The enclosure of the MPT-3048 is floating with respect to all circuit voltages and may be used with either negatively or positively grounded systems. It may also be used with systems in which neither negative nor positive are grounded, as allowed by NEC 690-41 for systems of less than 50 volts. Most systems are negatively grounded, or utilize an isolated ground to which neither negative nor positive conductors are grounded.
F Do not ground any positive or negative conductor within the enclosure of the MPT-3048. Always do so at a common location in the DC load center, and through a Ground Fault Protection Device (GFPD), to comply with NEC requirements. The equipment grounding conductor attached to the MPT-3048’s grounding lug should be an insulated wire with a minimum size of 10 gauge copper.
! The voltage between ground and the positive and negative connections to the controller must never exceed 100 volts.
For code compliance, basic electrical safety, and enhanced EMI shielding, one copper ground wire must be securely fastened to the enclosure. A lug and bolt are included with the unit and may be fastened to the 1/4” threaded hole in left side of the unit (Figure 11.3.1). The other end of the ground wire is connected to the grounded bus bar within your load center.

So, after all that I take it as a standard #10 ground wire from the CC enclosure to a Ground Buss, this states D/C Load Center meaning a ground buss in the panel enclosure. The assumption is that the "D/C Load Center" ground has been 'earthened' or connected to a ground rod.

Now how many of you out there connects your R/V's electrical systems "ground buss", if you even have one, to a ground rod, with a #6 wire between the rod and the buss?

Like I said, this is stick & brick code language.

I would agree on your interpretation. How would Rogue know where or how their CC's were going to be installed so probably err on the side of caution.

[Almot]

Ground rod? I wonder if anybody is using it unless they are stationary for more than a month.

Btw, browsing Rogue site, have noticed they will be making battery monitor based on their remote display. Prototype is being tested now.

[BoonHauler]

Here's what the manual states:

Rogue Manual wrote:
11.3 Grounding
The enclosure of the MPT-3048 is floating with respect to all circuit voltages and may be used with either negatively or positively grounded systems. It may also be used with systems in which neither negative nor positive are grounded, as allowed by NEC 690-41 for systems of less than 50 volts. Most systems are negatively grounded, or utilize an isolated ground to which neither negative nor positive conductors are grounded.
F Do not ground any positive or negative conductor within the enclosure of the MPT-3048. Always do so at a common location in the DC load center, and through a Ground Fault Protection Device (GFPD), to comply with NEC requirements. The equipment grounding conductor attached to the MPT-3048’s grounding lug should be an insulated wire with a minimum size of 10 gauge copper.
! The voltage between ground and the positive and negative connections to the controller must never exceed 100 volts.
For code compliance, basic electrical safety, and enhanced EMI shielding, one copper ground wire must be securely fastened to the enclosure. A lug and bolt are included with the unit and may be fastened to the 1/4” threaded hole in left side of the unit (Figure 11.3.1). The other end of the ground wire is connected to the grounded bus bar within your load center.

So, after all that I take it as a standard #10 ground wire from the CC enclosure to a Ground Buss, this states D/C Load Center meaning a ground buss in the panel enclosure. The assumption is that the "D/C Load Center" ground has been 'earthened' or connected to a ground rod.

Now how many of you out there connects your R/V's electrical systems "ground buss", if you even have one, to a ground rod, with a #6 wire between the rod and the buss?

Like I said, this is stick & brick code language.

[westend]

Sounds like a nice match up of panels and controller.

I was looking more at the GFPD for solar and Morningstar now makes a couple of them, they both mate logistically, with other Morningstar controllers. They basically serve as interruption similar to other GFI devices with the current differential being 300ma at interruption. Morningstar also notes that all PV devices also be grounded to earth ground. In the OP's case, he would not be making the connection from PV devices to frame ground any easier by using a dedicated GFPD.

I'm sort of old school about grounding, I don't like to connect grounds together at an intermediate junction point or multiple points, choosing to establish a direct path to the most direct point to earth. In my rig, that means that all of the 12V system connects to one point on the frame. The AC load center is also grounded at that same point. This isn't the Gospel, it's just the way I like to do it.

[Almot]

On the second thought - if you don't use GFP, there is no need in a common Ground bus. Just make sure ground wires are short. Common Neg bus can be skipped if this makes design easier.

[Almot]

Marc-the-rogue is incredibly thorough when it comes to engineering and instructions. I would trust Rogue manual and run controller ground to common Neg bus, unless this complicates the design too much. With GFP or not - not sure.

Rogue 20 wouldn't handle 400W. Rogue 30 can do ~500W at sea level.
Yes, Rogue display on model 30 is nice and very handy, it saved me a lot of money on not buying a battery monitor. But my situation is different, rig is in Mexico and batteries are full 9 days out of 10. If you will or already have a separate battery monitor, you won't really need Rogue display with model 20 but you would have to buy a data converter for more accurate initial tune-up.

brulaz wrote:
there's other MPPT controllers out there are cheaper and probably would have been good enough. But I'm a sucker for quality electronics, especially when they're designed and made in the Oregon woods.

I was unable to find any 30A MPPT that was cheaper than Rouge AND had same features and options. Living there for months with solar being the only source, I can't afford a controller that is just "good enough". Don't want it to screw up my batteries because of poor features.

Panels - I tend to think there is very little difference between manufacturers though it's better to choose a known brand, wherever it's made. Buying panels in Canada sucks, there is not much choice of brands, or you pay fortune in shipping costs.

[brulaz]

pianotuna wrote:
Hi,

I'd be most interested to know what panels you chose to go with the Rogue!

Whatever I could pickup locally that were max ~32" wide and reasonably high voltage (>40V) and reasonably priced.

Ended up with two of these 195W panels (Can$175 ea)) in parallel: SPM195 which are the "Sunny Power" brand (from China obviously).

The folks at 2Solar in Markham ON were great to work with. Fed us candy while the panels were packed in my car. Also got my 10ga MC4 cables there.

The Rogue could handle more watts, but my trailer couldn't take anything wider than 32", and I didn't want anything heavier anyway. I've heard of Canadian Solar 205W, 32" wide panels but was told they aren't available in Ontario, so 195W was the best I could come up with.

We'll see how the "Sunny Power" ones hold up ...

Was thinking about getting the 20A Rogue, but really wanted the fancier display. If you add the remote display to the 20A, it's getting close in price to the 30A, so went that way. To be honest, there's other MPPT controllers out there are cheaper and probably would have been good enough. But I'm a sucker for quality electronics, especially when they're designed and made in the Oregon woods.

[pianotuna]

Hi,

I'd be most interested to know what panels you chose to go with the Rogue!

[brulaz]

Good. I'll just forget the GFP.
Now I just have to wait for all the stuff to arrive and get wiring.
Currently plan a ground wire from the mppt to the breaker box, then to the PD9260 then to the frame, all separate from the neg wire going to the battery.
Thanks again folks.

[BoonHauler]

brulaz wrote:

BoonHauler wrote:

brulaz wrote:

Rogue says to run a separate 10ga from the MPPT grd terminal to "a common location in the DC load center, and through a Ground Fault Protection Device (GFPD), to comply with NEC requirements".

What sort of GFPD are people using if anything? Could I just connect the grd to the neg wire in the load center? Or should i just ignore the Mppt grd terminal?

What model controller do you have? I'd like to see what context they're refering to.

As for Ground Fault Breakers, here's a Link

Here's what that link says for the MNDC-GFP63:
"The 2011 NEC requires a GFP now on all systems. It used to be that they were required only when PV panels were installed on the roof of a dwelling. Now even if you Solarize your doghouse, a ground fault protector is required in order to pass inspection."

Sort of agrees with the quote from Rogue above. It's a Rogue 3048.

I presume you would put this between the mppt grd and the frame? Maybe if I ever place another order to NAWS I'll get one.

EDIT: Maybe not.

They seem to be high amperage 63A,80A and designed for grnd faults between grounded solar panels and battery neg. Half the MNDC-GFP63 is a 63A breaker between the solar panel + and the mppt + in (with another regular 63A breaker in series) and the other half breaker of the MNDC-GFP63 is from the solar panel grnd to battery neg.

My system is only 15A max with un-grounded solar panels.

brulaz:

I have yet to read the Rogue info but what a can say is the "NEC" code is for stick & brick structures and for the most part do not apply to RV's.

I'm with Westend on this one, just can't seem to understand why the GFP ....... :h

[brulaz]

BoonHauler wrote:

brulaz wrote:

Rogue says to run a separate 10ga from the MPPT grd terminal to "a common location in the DC load center, and through a Ground Fault Protection Device (GFPD), to comply with NEC requirements".

What sort of GFPD are people using if anything? Could I just connect the grd to the neg wire in the load center? Or should i just ignore the Mppt grd terminal?

What model controller do you have? I'd like to see what context they're refering to.

As for Ground Fault Breakers, here's a Link

Here's what that link says for the MNDC-GFP63:
"The 2011 NEC requires a GFP now on all systems. It used to be that they were required only when PV panels were installed on the roof of a dwelling. Now even if you Solarize your doghouse, a ground fault protector is required in order to pass inspection."

Sort of agrees with the quote from Rogue above. It's a Rogue 3048.

I presume you would put this between the mppt grd and the frame? Maybe if I ever place another order to NAWS I'll get one.

EDIT: Maybe not.

They seem to be high amperage 63A,80A and designed for grnd faults between grounded solar panels and battery neg. Half the MNDC-GFP63 is a 63A breaker between the solar panel + and the mppt + in (with another regular 63A breaker in series) and the other half breaker of the MNDC-GFP63 is from the solar panel grnd to battery neg.

My system is only 15A max with un-grounded solar panels.

[brulaz]

Thanks for the suggestions and info. Very helpful.

I'll keep the Mppt grnd separate from the Neg and run it to the breaker box grnd and then to the frame.

The Neg will go to the battery, not to the frame.

[westend]

As smkettner posted, ground the controller box to the frame with an individual ground. Run your (-) and (+) from the module-> controller and controller-> battery with two separate wires.

I can't understand the need for a GFI on the controller chassis ground.