Solar System Wiring into RV Distribution Panel

[JASHOTZE]

Its don't think it switches the neutral ground bond which is a problem not to be ignored.

Can you elaborate on this? I'm unfamiliar with this. the LV2424 and the Growatt 3000k seem to be almost identical and the one doesn't seem to have that issue from the user above.

Disconnect it from both ac and dc sides of the combined load center.
Then the dc topology will be
24_volt_domain->buck_converter->dc_load_center

So if the Inverter is always powering the AC distribution, whether from shore power or the battery bank, wouldn't the stock AC-DC convert work, since it was built to run in that exact manner? The only time the 24v would touch the system is into the inverter, from there it would only be coming out as 120v AC

 

[John Frum]

Can you elaborate on this? I'm unfamiliar with this. the LV2424 and the Growatt 3000k seem to be almost identical and the one doesn't seem to have that issue from the user above.

They both have the same problem.
They are not designed for the mobile usage model.
They are both designed for a residential setup where the neutral ground bond is at the service entrance and does not get switched.
I'm not an electrician so I don't want to get into the nitty gritty.
I will say that its a safety issue.

So if the Inverter is always powering the AC distribution, whether from shore power or the battery bank, wouldn't the stock AC-DC convert work, since it was built to run in that exact manner? The only time the 24v would touch the system is into the inverter, from there it would only be coming out as 120v AC

Yes with a little care you can run like this
24_volt_dc->inverter->ac2dc_converter->12_volt_load_center
It is horribly inefficient though
its 80 percent of 85 percent
Alternatively you could do
24_volt_dc->dc2dc_converter->12_volt_load_center
at 90% efficiency
or... you could do a 12 volt system
12_volt_dc->12_volt_load_center
with near 100% efficiency

 

[JASHOTZE]

They both have the same problem.
They are not designed for the mobile usage model.
They are both designed for a residential setup where the neutral ground bond is at the service entrance and does get switched.
I'm not an electrician so I don't want to get into the nitty gritty.
I will say that its a safety issue.


Yes with a little care you can run like this
24_volt_dc->inverter->ac2dc_converter->12_volt_load_center
It is horribly inefficient though
its 80 percent of 85 percent
Alternatively you could do
24_volt_dc->dc2dc_converter->12_volt_load_center
at 90% efficiency
or... you could do a 12 volt system
12_volt_dc->12_volt_load_center
with near 100% efficiency

Ok, I’ll look into the ground issue then.

As for the 12 vdc that makes perfect sense. I was planning a 24 volt system just for the simplicity of expansion and lower amps so lower huge wires throughout.
if I go with the 24v>converter> 12 v distribution panel would I need some sort of low voltage cutoff to stop the battery’s from getting to low voltage cutoff by the BMS?

 

[John Frum]

Ok, I’ll look into the ground issue then.

As for the 12 vdc that makes perfect sense. I was planning a 24 volt system just for the simplicity of expansion and lower amps so lower huge wires throughout.
if I go with the 24v>converter> 12 v distribution panel would I need some sort of low voltage cutoff to stop the battery’s from getting to low voltage cutoff by the BMS?

You need the bms to do that regardless as the last line of defense.
Your inverter should also do that.
Depending on the dc loads you may have to address that separately.
A layered strategy is usually indicated.

 

[JASHOTZE]

You need the bms to do that regardless as the last line of defense.
Your inverter should also do that.
Depending on the dc loads you may have to address that separately.
A layered strategy is usually indicated.

Yea I know the BMS can and will. I was just under the impression that allowing it to happen is not ideal for the batteries.

 

[John Frum]

Yea I know the BMS can and will. I was just under the impression that allowing it to happen is not ideal for the batteries.

That is why your all in one should also be configured for low voltage disconnect.
You might even want low voltage disconnect for your dc loads.

Here is a strategy,
The all_in_one is set to disconnect at 24.1 volts.

Next disconnect is for the dc loads at 24.0 volts using a victron battery protect. https://www.victronenergy.com/battery_protect/battery-protect

Then finally the bms disconnects the battery from all loads at 23.9 volts.

 

[Whinny]

What were you wanting to power with the inverter? Some stand alone inverters do bond neutral, I know mine does. Going bigger than you need can have drawbacks and certainly add complexity. You probably have a WFCO converter/breaker/fuse panel? It's easy to remove and bypass the existing converter. The trailer breakaway can be solved with one of these, they are common on boat trailers...
https://www.etrailer.com/Trailer-Breakaway-Kit/Hopkins/20400.html

 

[JASHOTZE]

What were you wanting to power with the inverter? Some stand alone inverters do bond neutral, I know mine does. Going bigger than you need can have drawbacks and certainly add complexity. You probably have a WFCO converter/breaker/fuse panel? It's easy to remove and bypass the existing converter. The trailer breakaway can be solved with one of these, they are common on boat trailers...
https://www.etrailer.com/Trailer-Breakaway-Kit/Hopkins/20400.html

The inverter will be wired to the AC distribution panel of the RV. So that all of the electricity will work as normal. I do not plan on usin the AC or microwave via only solar unless I get a large enough battery bank eventually.

I have not come across or read about anything involving bond neutral issues. Which leads me to assume it isn’t much of an issue.

 

[John Frum]

"To prevent a fire, electric shock, improper operation of circuit protection devices, as well as improper operation of sensitive equipment, the grounding of electrical systems, the bonding of equipment and circuit conductors must be done in a manner that prevents objectionable current (neutral return current) from flowing on conductive materials, electrical equipment, or on grounding and bonding paths [250.6].

This is accomplished by keeping the grounded (neutral) conductor separated from the metal parts of electrical equipment, except as required for service equipment in 250.24(B) and separately derived systems in 250.30(A)(1)] in accordance with 250.142." -- https://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/Neutral-to-GroundConnections~20020521.htm

Difference between UL458 & UL 1741 For Power Inverters

Difference between UL458 & UL 1741 For Power Inverters According to the National Electrical Code, batteryless (on grid) or battery-based (off grid / hybrid) power inverter used in residential renewable energy systems must be listed to UL1741. While UL458 is the safety standard for Power...

www.sigineer.com

 

[John Frum]

Grounding details for specific make/model of inverters

To get to the paper, click on the orange button at the top of the screen. It is important to understand how an inverter handles grounding in order to set it up correctly. Unfortunately, many inverters do not provide adequate documentation on...

diysolarforum.com

 

[JASHOTZE]

Grounding details for specific make/model of inverters

To get to the paper, click on the orange button at the top of the screen. It is important to understand how an inverter handles grounding in order to set it up correctly. Unfortunately, many inverters do not provide adequate documentation on...

diysolarforum.com

Thanks for that. Forgive my ignorance, Im a fairly handy guy and been a helicopter mechanic for 15 years, but this is Chinese to me about grounding. I understand the basic grounding principles of electricity but does this mean I need to do anything different than ground to the vehicle chassis?

 

[John Frum]

Thanks for that. Forgive my ignorance, Im a fairly handy guy and been a helicopter mechanic for 15 years, but this is Chinese to me about grounding. I understand the basic grounding principles of electricity but does this mean I need to do anything different than ground to the vehicle chassis?

Grounding is a complicated topic.
As I said I'm not an electrician and hesitate to get deep into it.
When you ground to the vehicle chassis that has 2 main connotations.
1. Using the chassis as the return part of the circuit.
2. Using the chassis as the 0 voltage reference.

Please don't do option 1 and I'm not talking about 2.
What I am talking about is making sure your alternating current system doesn't hurt people or pets or start a fire.
Neutral and ground must be properly bonded under all circumstances so that fault conditions have a nice low impedance path back to source in order to clear fault conditions.
Think of what happens with a metal case 3 prong plug appliance in the case where the hot wire comes in contact with the case.
If you have a single neutral ground bond the fault current makes its way back to the breaker via the ground wire traversing to neutral at the bond to pop the breaker and clear the fault.
A nice low impedance path to ensure the breaker trips.
A real bad scenario is a person being part of the return path injuring or killing them.
Might not even trip the breaker, just continues to cook them.

 

[JASHOTZE]

Grounding is a complicated topic.
As I said I'm not an electrician and hesitate to get deep into it.
When you ground to the vehicle chassis that has 2 main connotations.
1. Using the chassis as the return part of the circuit.
2. Using the traffic as the 0 voltage reference.

Please don't do option 1 and I'm not talking about 2.
What I am talking about is making sure your alternating current system doesn't hurt people or pets or start a fire.
Neutral and ground must be properly bonded under all circumstances so that fault conditions have a nice low impedance path back to source in order to clear fault conditions.
Think of what happens with a metal case 3 prong plug appliance in the case where the hot wire comes in contact with the case.
If you have a single neutral ground bond the fault current makes its way back to the breaker via the ground wire and traverses to neutral at the bond to pop the breaker and clear the fault.
A real bad scenario is a person being part of the return path injuring or killing them.
Might not even trip the breaker, just continues to cook them.

Ok I think I am following. I’ve been scrubbing through here and noticed you bring up ground bond neutral on almost every RV solar post. So I would assume someone has accomplished a straightforward fix for this issue and I would also assume you know it since it seems to be the main thing you’re worried about.
Only fix I have found wasn’t very straightforward. But please let me know if I have it straight.

using an LV2424 I have the the shore power wired in to AC in. The AC out is wired to the AC distribution panel of the RV. When using shore power the ground is coming from the shore power. When using battery power the ground would be to the chassis. So I need to do something to make sure it switches when the power input switches?
Is this a relay of some sort?

 

[John Frum]

When using shore power the ground is coming from the shore power.

In this scenario the neutral/ground bond is upstream of the pedestal and out of your control.
Fault current therefore has a low impedance path through the breaker so that it can clear the fault condition.

When using battery power the ground would be to the chassis.

Not the chassis.
You need to have a local neutral/ground bond for this scenario.
The ground wire needs a single low impedance path pack to the source(hopefully through a breaker).

So I need to do something to make sure it switches when the power input switches?
Is this a relay of some sort?

This has been accomplished by at least one person with a relay.
He knew what he was doing and his father and brother were both electricians iirc.
BTW I'm not the only one that warns folks about this.
I'm going to stop talking now.

 

[John Frum]

Maybe this will help.

What Is the Third Prong on the Plug? | Mister Sparky

What’s the third prong on a plug? It’s actually for the ground wire to keep you and your environment safe. Learn more about ground connectors.

www.mistersparky.com

 

[JASHOTZE]

Maybe this will help.

What Is the Third Prong on the Plug? | Mister Sparky

What’s the third prong on a plug? It’s actually for the ground wire to keep you and your environment safe. Learn more about ground connectors.

www.mistersparky.com

So found a pretty good article on a similar forum here and think I have a decent grasp of the concept. https://sprinter-source.com/forums/index.php?threads/50083/

From reading the listing put together on the link you provided about certain inverters, it’s sounds like the lv2424 bonds ground to neutral when not on shore power. Which sounds like it handles the issue without a separate relay.

 

[John Frum]

Got it wrong last night.
The over current protection is on the hot side of course.