Grounding solar panels on a RV or trailer.

[69GP]

Hi,

This is my first post here. I was curious if there have been any guidelines set up for grounding panels on a RV or a trailer. I only ask because another web site that I follow people are installing 400watt panels with no type of grounding of the panels. IMHO I find this to be pretty dangerous if the panel should become energized and somehow someone got between the panel and some metal object on the roof.

does anyone have an opinion.

[Sunking]

If they are typical 12 volt battery panels there is no requirement to ground the panels and no real benefit from doing so. As long as the output leads are fused they are safe from any faults. Besides if the mounting hardware is steel or some kind of conductive mateial fastened to the sheet metal of the RV it is grounded anyway.

[69GP]

If they are typical 12 volt battery panels there is no requirement to ground the panels and no real benefit from doing so. As long as the output leads are fused they are safe from any faults. Besides if the mounting hardware is steel or some kind of conductive mateial fastened to the sheet metal of the RV it is grounded anyway.

Hi,

Some of these systems are 24 and 36 volts and up to 1000 watts. As for the grounding a lot of these systems are on racks with hinges to tip the panels toward the sun therefore not making for a solid ground. As for the the type of steel or hardware being used I was under the impression that any type of connection for ground needed to approved for that use, such as a pass thru lug.

Just seems to me that the same rules that apply to a permentate type mounting should apply to a rv or trailer,since they do use inverters to run 110 volt onboard systems. Also these rv and trailers do plug into 30 and 50amp 110 volt receptacles.

Not trying to stir the pot just seems to me that it could cause a problem under the right conditions.

Steve B

[Mike90250]

Hi,

Some of these systems are 24 and 36 volts and up to 1000 watts. As for the grounding a lot of these systems are on racks with hinges to tip the panels toward the sun therefore not making for a solid ground. As for the the type of steel or hardware being used I was under the impression that any type of connection for ground needed to approved for that use, such as a pass thru lug.

Just seems to me that the same rules that apply to a permentate type mounting should apply to a rv or trailer,since they do use inverters to run 110 volt onboard systems. Also these rv and trailers do plug into 30 and 50amp 110 volt receptacles.

Not trying to stir the pot just seems to me that it could cause a problem under the right conditions.

Steve B

24 & 36 V RV systems are quite rare. I know of no RV roof large enough to hold 1,000 w worth of panels. Maybe a giant converted tour bus is large enough.

The RV hook-up at the trailer park, is supposed to provide any required grounding, it takes about 20 seconds to see the folly of 200 RV's pulling into a park, and trying to drive their ground rods, and finding the water or septic lines. And then pulling the rods out a week later.

Many "mod sine/square" wave inverters will instantly smoke on a grounded system.

[epsgunner]

On the type that swing up.. the simple fix is a ground strap long enough to do the job..

What people do to there RV unfortunately really regulated from what I've been reading..

Unless DOT regulates them.. then all bets are off to individual installs.. I would think RV install places though would ground everything as best they could..

[69GP]

24 & 36 V RV systems are quite rare. I know of no RV roof large enough to hold 1,000 w worth of panels. Maybe a giant converted tour bus is large enough.

The RV hook-up at the trailer park, is supposed to provide any required grounding, it takes about 20 seconds to see the folly of 200 RV's pulling into a park, and trying to drive their ground rods, and finding the water or septic lines. And then pulling the rods out a week later.

Many "mod sine/square" wave inverters will instantly smoke on a grounded system.

Hi Mike,
Thanks for replying.

Couple of things. I have a 28' class A motor home and could easily fit 4 sharp 235 watt panels on the roof and still be able to move around, so getting that many watts or more on a motorhome or trailer is not a problem.

The only reason I brought this up is because I have seen photos of at least 20 systems on trailers and rvs that did not have any grounding to the panels.

I am a master electrician and have owned my own business for 20 years. I do commercial and industrial work only. I have done 500 megawatt power plant with less hassle then installing solar panels on my own house. In order to even get an electrical permit to install the system on my house I had to provide more information then any project that I have ever done, including ground lugs ground clips for attaching the panels to the rails, mounting hardware and every piece of information that came with the inverter, meter, optimizers and on top of that I had to listen to some 25 year old electrical inspector tell me about the dangers with a solar system. I would not mind listening to someone if they knew what they were talking about but he did not even know what a supplementary ground was.

My friend is a state investigator for the board of professional liscencesure for electricians. He has told me that there have been several fires in residential dwellings artributed to grounding issues. I really do not see the difference between a. Rv and a house when it comes to the panels.

Should these panels at least be grounded to the frame of the vehicle?



Steve B

[Sunking]

I am a master electrician and have owned my own business for 20 years. I do commercial and industrial work only.

OK Steve I am a PE with 30 years of experience. First comment is RV or any automobile boat, ship etc.. are not under jurisdiction of the NEC.

So let me ask you this. What purpose would it serve to ground the panels? If you want to apply the rules of the NEC , the NEC does not require the Solar systems under 50 volts to be grounded. I would never ground one because it makes them unreliable and more dangerous. Al the NEC requires for systems under 50 volts is over current protection and I can do that quite well without grounding anything.

You can also find this question over on Mike Holt Code Forum for which I am a moderator.

[69GP]

On the type that swing up.. the simple fix is a ground strap long enough to do the job..

What people do to there RV unfortunately really regulated from what I've been reading..

Unless DOT regulates them.. then all bets are off to individual installs.. I would think RV install places though would ground everything as best they could..

Thanks for the reply. I agree with you that a grounding strap be used.

Just cannot figure out why nobody who mounts them on there rv or trailer is grounding them.


Steve b

[Sunking]

Just cannot figure out why nobody who mounts them on there rv or trailer is grounding them.

Because it serves no purpose what so ever. It is just wasted material and money that does nothing.

[69GP]

OK Steve I am a PE with 30 years of experience. First comment is RV or any automobile boat, ship etc.. are not under jurisdiction of the NEC.

So let me ask you this. What purpose would it serve to ground the panels? If you want to apply the rules of the NEC , the NEC does not require the Solar systems under 50 volts to be grounded. I would never ground one because it makes them unreliable and more dangerous. Al the NEC requires for systems under 50 volts is over current protection and I can do that quite well without grounding anything.

You can also find this question over on Mike Holt Code Forum for which I am a moderator.

Hi Dereck,

The only thing that I can see that could pose a issues is if the frame on the panel became energized and someone was on the roof. If the frame was hot and a person touched the energized frame and say a roof mounted ac unit or a roof top antena you could get a pretty good jolt. most rv roofs are PVC composite material and the systems are mounted on sleepers that are glued down to the roof and the PVC rubber is the glued over the sleepers to make a watertight seal. By doing this the racking is not grounded.

Like I said just trying to find out if it's a safe way to install

Thanks again for your reply

Steve b

I did not look on Mike Holts site

[Sunking]

Steve stop and think for a minute. You know what isolation an transformers are right? You know what a grounded system is right?

Let's say I take a 120 VAC standard residential circuit to an outside isolation transformer and connect it to the primary. On the secondary I choose not to ground L2 terminal and float the secondary. I fire the transformer up. I reach in and touch the secondary L1 terminal. What happens to me?

Nothing happens to me.

Now lets ground the secondary L2 terminal. Now I reach in and touch L1. What happens to me? I get the chit shocked out of me if I am grounded.

[69GP]

OK Steve I am a PE with 30 years of experience. First comment is RV or any automobile boat, ship etc.. are not under jurisdiction of the NEC.

So let me ask you this. What purpose would it serve to ground the panels? If you want to apply the rules of the NEC , the NEC does not require the Solar systems under 50 volts to be grounded. I would never ground one because it makes them unreliable and more dangerous. Al the NEC requires for systems under 50 volts is over current protection and I can do that quite well without grounding anything.

You can also find this question over on Mike Holt Code Forum for which I am a moderator.

Hi Dereck,

The only thing that I can see that could pose a issues is if the frame on the panel became energized and someone was on the roof. If the frame was hot and a person touched the energized frame and say a roof mounted ac unit or a roof top antena you could get a pretty good jolt. most rv roofs are PVC composite material and the systems are mounted on sleepers that are glued down to the roof and then PVC rubber is glued over the sleepers to make a watertight seal. By doing this the racking is not grounded.

I did not look at Mike Holts site as I knew that this situation would not be covered by the NEC

Like I said just trying to find out if it's a safe way to install

Thanks again for your reply

Steve b

[Sunking]

Like I said just trying to find out if it's a safe way to install

That is the right question. Answer: fuse both polarities. If one side becomes grounded nothing happens. Ever work on 3 phase Delta non grounded systems? Know why they are not grounded systems.

[69GP]

Steve stop and think for a minute. You know what isolation an transformers are right? You know what a grounded system is right?

Let's say I take a 120 VAC standard residential circuit to an outside isolation transformer and connect it to the primary. On the secondary I choose not to ground L2 terminal and float the secondary. I fire the transformer up. I reach in and touch the secondary L1 terminal. What happens to me?

Nothing happens to me.

Now lets ground the secondary L2 terminal. Now I reach in and touch L1. What happens to me? I get the chit shocked out of me if I am grounded.

Lol guess your right, sometimes I look at things a little to complicated.

Thanks

Steve b

[Sunking]

Lol guess your right, sometimes I look at things a little to complicated.

Thanks

Steve b

You are welcome Steve. Instead of answering you directly, I am trying to lead you to the answer in hopes you understand why.

For NEC applications residential systems are grounded for on 5 reasons.

• Planned path for lightning and static charges to discharged
• To clear high voltage faults. Example primary distribution coming into contact with secondary distribution. Or a high voltage line falling down onto your service lateral.
• A planned path for fault currents to operate OCPD.
• Limit touch potential; voltages to reasonable limits of 50 volts or less