Grounding panel frames on a RV

[emerge411]

I have started my install on my RV and got hung up on grounding of the solar panel frames. Initially I was planning on grounding the frames and also using a DC SPD on the positive and negative connection from the panels. I have not seen these connections in any RV based installs I have seen online so I am second guessing myself. Should I remove the highlighted/brighter connections (panel ground and SPD) from my install?

The following doc indicates the frames should be grounded. https://diysolarforum.com/resources/grounding-made-simpler-part-4-mobile-systems.159/

There are only few threads specifically on this topic applied to RVs and they are unclear to me. There seems to be some argument about the need to ground the frames in a system that is grounded to the chassis but not to the actual earth/dirt via a grounding rod or the like. This would be the case when the RV is not connected to AC power which will be often.

I believe NEC would indicate I should ground the frames (Vmax 50v+) but professional solar installs on RVs seem to always skip it.

 

[FilterGuy]

I have started my install on my RV and got hung up on grounding of the solar panel frames. Initially I was planning on grounding the frames and also using a DC SPD on the positive and negative connection from the panels. I have not seen these connections in any RV based installs I have seen online so I am second guessing myself. Should I remove the highlighted/brighter connections (panel ground and SPD) from my install?

The following doc indicates the frames should be grounded. https://diysolarforum.com/resources/grounding-made-simpler-part-4-mobile-systems.159/

There are only few threads specifically on this topic applied to RVs and they are unclear to me. There seems to be some argument about the need to ground the frames in a system that is grounded to the chassis but not to the actual earth/dirt via a grounding rod or the like. This would be the case when the RV is not connected to AC power which will be often.

I believe NEC would indicate I should ground the frames (Vmax 50v+) but professional solar installs on RVs seem to always skip it.

View attachment 73677

I highly recommend you ground the frames to the chassis. When driving the airflow can create static charges that should be dissipated if at all possible.

There are a few options on grounding the frames.

If the mounting method is all metal and naturally connects the frames to the chassis, then make sure it is a good connection and call it good. Any additional grounding wires would almost certainly create ground loops. (Notice that with this, the frames are grounded to the chassis but there are no obvious grounding wires.)

If the mounting method does not electrically connect the frames to the chassis, then grounding should be added. The grounding can either go directly to the chassis or go to your common DC negative and then to the chassis. (Do not do both because it might create a ground loop).

 

[FilterGuy]

I highly recommend you ground the frames to the chassis. When driving the airflow can create static charges that should be dissipated if at all possible.

There are a few options on grounding the frames.

If the mounting method is all metal and naturally connects the frames to the chassis, then make sure it is a good connection and call it good. Any additional grounding wires would almost certainly create ground loops. (Notice that with this, the frames are grounded to the chassis but there are no obvious grounding wires.)

If the mounting method does not electrically connect the frames to the chassis, then grounding should be added. The grounding can either go directly to the chassis or go to your common DC negative and then to the chassis. (Do not do both because it might create a ground loop).

Just to be clear. The system may never have a problem if the frames are not grounded..... but I figure that it is easy enough to ground them so why take a chance.

 

[Kapow_Network]

@FilterGuy Apparently, here are pictures of systems that were NOT grounded, and did have a problem:

 

[wmgeorge]

@FilterGuy Apparently, here are pictures of systems that were NOT grounded, and did have a problem:

If it was ground or roof mounted but these are on a RV on rubber tires. The reason you can not get a reading with your meter on the aluminum has nothing to do with a ground, the aluminum in the video has a protective coating your meter leads points did not penetrate.

 

[Zil]

Is there any evidence of static build up from wind or air flow on panels mounted on a RV? Record of damage?

 

[Paul_R]

I'm not convinced that panels need to be grounded on an RV, but mine are because my aluminum mounts are screwed into the aluminum trailer frame.

 

[Kapow_Network]

I'm not convinced that panels need to be grounded on an RV, but mine are because my aluminum mounts are screwed into the aluminum trailer frame.

It may take awhile, but I think I'm going to err on the side of caution and ground. Otherwise my frame goes into PT wood framing I built on roof. Lightening could be an issue. Of course, I should win the lottery before my unit is struck by lightning, BUT sometimes mother nature doesn't follow my orders. I'm also trying to study the issue of ground looping (because it sounds like I don't want a ground loop).

 

[Paul_R]

If it was ground or roof mounted but these are on a RV on rubber tires. The reason you can not get a reading with your meter on the aluminum has nothing to do with a ground, the aluminum in the video has a protective coating your meter leads points did not penetrate.

Panel frames are anodized, which is non conductive.

It may take awhile, but I think I'm going to err on the side of caution and ground. Otherwise my frame goes into PT wood framing I built on roof. Lightening could be an issue. Of course, I should win the lottery before my unit is struck by lightning, BUT sometimes mother nature doesn't follow my orders. I'm also trying to study the issue of ground looping (because it sounds like I don't want a ground loop).

I wouldn't stress over it. And don't go thinking that being grounded is going to make any difference whatsoever if your panel is actually struck by lightning

 

[12VoltInstalls]

I'm going to err on the side of caution and ground

Maybe it’s from being around small boats where some issues are ‘amplified,’ but I’m of the opinion that won’t hurt anything and ‘may’ have a benefit. But not for lightning.

also trying to study the issue of ground looping (because it sounds like I don't want a ground loop)

Now THAT is an important thing to do.

If it was ground or roof mounted but these are on a RV on rubber tires

There seems to be some argument about the need to ground the frames in a system that is grounded to the chassis but not to the actual earth/dirt via a grounding rod

I think everything in a vehicle should be connected to a single point so that electrical potential doesn’t exist outside + and - conductors.

In an RV and in an independent off grid system with no grid connection to the dirt or structure the frame of the RV or the central neg/ground busbar is in principle The Ground the same as dirt is in grid connected systems- ‘code’ notwithstanding. (Once an RV is plugged in or an offgrid cabin gets grid power this is no longer exclusively true and grounding must be handled for the practical potential danger and electrical code to be safe)

So the RV if properly wired for shore power and plugged in to a properly wired grid power stanchion will be grounded through the stanchion, and the cabin if connected to grid would then have earth/dirt grounding established by a ground rod.

The point is grounding to the ‘frame’ doesn’t harm anything and has possible beneficial effects.

As far as lightning, if an RV is struck by lightning one of two things- or both- would happen. The Van De Graff effect would ‘maybe’ protect the camper if metal, or the roof mounted solar panels would become a conductor and lightning would arc from frame to ground. In both cases various free-willy electrical energy may and probably would travel every possible path of opposing potential and kill electronics. Resistive paths direct to dirt/earth would likely create high heat and potentially combustion of nearby materials would begin, and balls of electrons may even be seen rolling about the floor.
I could be incorrect but I’ve always believed the Van De Graff Effect would likely protect you in a vehicle more often than not, but electronics may not appreciate the experience. Grounding panel frames on an RV may have no positive effect but I don’t think it hurts anything.

 

[OneStudPuppy]

Interesting thread. I have been having similar thoughts in the grounding department. Know I still need to change my shore power plug as it has no ground pin. And it’s a fiberglass rig so another twist to throw in the conversation.
Shore power goes to a circuit box one outlet and there is two leads not used.
Solar will power house lights, a power port and 2 usb sockets. Biggest draw will be cpap to the power port. Max 80 watts at 12v but probably less using no humidity etc

 

[Zil]

Could someone explain how my 12 volt dc RV and vehicle wiring has a "ground loop" ?

 

[FilterGuy]

Grounding panel frames on an RV may have no positive effect but I don’t think it hurts anything.

Don't discount the static build-up that can occur with the wind blowing over the frames while driving. Tieing the frames to the chassis helps ensure the charge of the panel frames does not get way different than the charge of the vehicle.

I personally also like to tie the DC circuit to the chassis. This ensures the potential of the DC does not float to a voltage that is way different from the Chassis. Tying both the frames and the DC to the chassis ensures the potential between any two points in the system stays low.

 

[12VoltInstalls]

Don't discount the static build-up that can occur with the wind blowing over the frames while driving.

I probably do unintentionally discount static

Tieing the frames to the chassis helps ensure the charge of the panel frames does not get way different than the charge of the vehicle.

10-4

Tying both the frames and the DC to the chassis ensures the potential between any two points in the system stays low.

that’s how I see it.
Tied grounds in boats can stop fast anode erosion. Air isn’t water but it makes sense to me.

 

[Zil]

I can find no other information that wind causes a build up of static on solar panels on a vehicle.

 

[HRTKD]

I've seen static build up on my woodshop dust collector as well as my cordless leaf blower. But I think it's the dust particles that causes that, not the wind.

 

[12VoltInstalls]

I've seen static build up on my woodshop dust collector as well as my cordless leaf blower. But I think it's the dust particles that causes that, not the wind.

Neither.

Air + particles + movement creates static charges. I’m not sure but I don’t think you can get static without movement of particles.

If you get static on your dust collector that’s a fire/explosion hazard. You either need to remove and clean - or install- the bare copper grounding conductor in your ductwork. Static is why grain elevators and sawmills explode. Or rather- static discharge.

 

[Paul_R]

I'm sure static does build up on polar panels just like on the rest of your RV but I don't think it's enough to be concerned about. Ever touch a car and get zapped? I'm sure we all have.