Decided to go with 12V system, but i think i pushed it to the max. I am a new to this. i figured out that i needed a total of 2300W to power my devices, so i settled on a 12V 3000W inverter,, but then i came across a deal on the lifepo4 batteries, where the cost was extremely low compared similar batteries I was looking at. So in my excitement i brought three lifepo4 batteries. Now im stuck with them and i now think i messed up. These aren't 12V 100ah batteries that i see everyone going with, these are three 12V 300ah 200A BMS lifepo4 batteries. So my system is actually a 12V 900ah 200A BMS solar generator system. I found a 80A MPPT controller that can handle 1,200W of solar. I got the wiring down as, i split the system into two legs. So instead of having wires that are carrying 613A, I have one leg that is 350A (Inverter) and the other leg that is 300A. (MPPT, Fuse Box, 60A AC/DC Charger). So now i am having a problem with how to ground. From what i gather i have to ground my 1,200W solar array with an 8' grounding rod that is then tied to the main service grid ground rod {is that right?). Now on the other side of my system, which is on wheels and can be disconnected and packed up fairly easily for transport This is what is bothering me now. Since it is not connected to the house electrical system (may in the future) do i ground it or not? With it being a 12V system and NEC 250 saying I don't have to ground anything that is below 60 Volts, yet i wanted the extra safety feature of grounding especially when hooked up to the solar array. So do i then connect the grounding screws on the inverter and the MPPT to a grounding busbar, then run it to the negative battery busbar to create my ground that way? or do i just not bother with grounding my devices at all? Also, if i decide to ground this side when it is hooked up to solar should I attach the MPPT and Inverter to a ground busbar, then tie it directly to either the PV solar grounding rod (which is connected to the grid grounding rod) or do i attach it directly to the grid ground rod? I am kinda stuck on what to do, so I can move forward.
To "Ground or Not to Ground" and How?
- Thread starter ManKzin
- Start date
robbob2112
Doing more research, mosty harmless
wall of text hard to read - break things up a bit - used chatgpt to make it easy to read - will respond when I actually read it in a minute
I decided to go with a 12V system, but I think I pushed it to the limit. I'm new to this. I figured out that I needed 2300W to power my devices, so I settled on a 12V 3000W inverter.
Then, I came across a great deal on LiFePO4 batteries. The price was much lower than similar batteries I had been considering, so I bought three of them in my excitement. Now, I’m stuck with them and think I might have made a mistake.
These aren’t the typical 12V 100Ah batteries everyone seems to use. Instead, I have three 12V 300Ah batteries with 200A BMS each. That means my system is effectively a 12V 900Ah system with a 200A BMS, creating a powerful solar generator setup.
I’m struggling with how to ground the system. Here's what I’ve figured out and the questions I still have:
I’m stuck on how to handle grounding and need advice to move forward. Any guidance would be much appreciated!
I decided to go with a 12V system, but I think I pushed it to the limit. I'm new to this. I figured out that I needed 2300W to power my devices, so I settled on a 12V 3000W inverter.
Then, I came across a great deal on LiFePO4 batteries. The price was much lower than similar batteries I had been considering, so I bought three of them in my excitement. Now, I’m stuck with them and think I might have made a mistake.
These aren’t the typical 12V 100Ah batteries everyone seems to use. Instead, I have three 12V 300Ah batteries with 200A BMS each. That means my system is effectively a 12V 900Ah system with a 200A BMS, creating a powerful solar generator setup.
My Current Setup:
- Inverter: 12V, 3000W
- Batteries: 3 x 12V 300Ah (900Ah total, 200A BMS)
- Solar Charge Controller: 80A MPPT (handles up to 1200W solar)
- Wiring:
- Split into two legs to manage current:
- One leg handles 350A (for the inverter)
- The other leg handles 300A (for MPPT, fuse box, and 60A AC/DC charger).
- Split into two legs to manage current:
The Problem: Grounding
I’m struggling with how to ground the system. Here's what I’ve figured out and the questions I still have:
- Solar Array Grounding:
- I understand the 1200W solar array needs to be grounded with an 8' grounding rod, which should tie into the main service grid grounding rod. Is this correct?
- Portable System Grounding:
- My system is on wheels, so it’s portable and can be disconnected from the house easily.
- Since it’s not connected to the house’s electrical system (yet), do I even need to ground it?
- NEC 250 says grounding isn’t required for systems below 60V, but I still want the extra safety, especially when the solar array is connected.
- How to Ground the Components:
- Should I connect the grounding screws on the inverter and MPPT to a ground busbar, then run that to the negative battery busbar?
- Or should I skip grounding entirely since it’s a 12V system?
- When Connected to Solar:
- If I decide to ground this side when connected to solar, should I:
- Attach the MPPT and inverter to a ground busbar, then tie it to the solar grounding rod (connected to the grid rod)?
- Or should I connect it directly to the grid grounding rod?
- If I decide to ground this side when connected to solar, should I:
What I Need:
I’m stuck on how to handle grounding and need advice to move forward. Any guidance would be much appreciated!
robbob2112
Doing more research, mosty harmless
Question - is the array going to be portable as well, or will it be mounted static?
If it is portable then you would need a short rod solution like the ones that are multiple rods at 4ft you can put in and remove or the ones that look like a screw that go in and come out easy.
This applies either way
So, in plug in mode you get ground and the N-G bond from the house
In portable mode you get your ground from the rod(s) you put in wherever you are, and you need a connection from the AC neutral to the ground.
All grounds tie together -
In a mobile system like a car/rv/boat the pv negative ties to the chassis and grounding
in a cart you would not do this and in a house you would not do this.
The whole idea of grounding is two fold - first all the equipment shells and anything you can touch is at the same potential because it is tied together to the same grounding system. The second part is that there is a N-G bond so you have a way to clear a fault when a short happens.
If it is portable then you would need a short rod solution like the ones that are multiple rods at 4ft you can put in and remove or the ones that look like a screw that go in and come out easy.
This applies either way
- The panel frames get attached to the EGC that goes along with the PV wires - so you have 3 wires from the MPPT to the panels - PV+, PV-, and EGC (equipment ground conductor) - there is NO rod at the array
- Portable systems have one more wrinkle - the N-G bond - when you are plugged into the house you get the N-G bond from the house wiring. When you are not plugged into the house you need to have a N-G bond on the cart. You can't have both at the same time without blowing things up and letting the magic smoke out.
So, in plug in mode you get ground and the N-G bond from the house
In portable mode you get your ground from the rod(s) you put in wherever you are, and you need a connection from the AC neutral to the ground.
All grounds tie together -
In a mobile system like a car/rv/boat the pv negative ties to the chassis and grounding
in a cart you would not do this and in a house you would not do this.
The whole idea of grounding is two fold - first all the equipment shells and anything you can touch is at the same potential because it is tied together to the same grounding system. The second part is that there is a N-G bond so you have a way to clear a fault when a short happens.
robbob2112
Doing more research, mosty harmless
and note - I bought one of the 12v300ah wattcycle batteries - it came with the top unsnapped so I was able to look at it inside - it is as well built as the teardown Will did on the 12v100ah version -
I just completed a capacity test on it and it comes out around 3920Wh - so slightly over the capacity rated for.... took around 26.5 hours to run.
Putting 3 in parallel gives you more capacity which means a much longer runtime. The BMS max current is 200amps which is comparable to other setups. For I while I was running 12v200ah x 4 in parallel - so 12v800ah -
So there is nothing wrong with 12v900ah - what the 12v limits is the practical maximum wattage you can do. This limit is all about wire size and fuse sizes. In theory they can deliver 7680w, in practice the wires are multiple runs of 4/0 and the inverters don't have a way to attach that easy.
You can technically strings them in series with balancers to keep them together for higher voltage but all the current crop of balancers are max of 10amps. I am not sure that would be enough to keep them in balance if they got way out ... the larger batteries are uncharted waters.
I just completed a capacity test on it and it comes out around 3920Wh - so slightly over the capacity rated for.... took around 26.5 hours to run.
Putting 3 in parallel gives you more capacity which means a much longer runtime. The BMS max current is 200amps which is comparable to other setups. For I while I was running 12v200ah x 4 in parallel - so 12v800ah -
So there is nothing wrong with 12v900ah - what the 12v limits is the practical maximum wattage you can do. This limit is all about wire size and fuse sizes. In theory they can deliver 7680w, in practice the wires are multiple runs of 4/0 and the inverters don't have a way to attach that easy.
You can technically strings them in series with balancers to keep them together for higher voltage but all the current crop of balancers are max of 10amps. I am not sure that would be enough to keep them in balance if they got way out ... the larger batteries are uncharted waters.
Thanks for reorganizing my poor writing style and grammar mess. I wrote my post on a cell phone and it never occurred to me to do it in bullet point style to make it more legible.
Again, thank you Robbob2112.
Now to answer your question and rephrase what I am doing, so that you and others can get a better handle on what I am trying to accomplish.
Question - is the array going to be portable as well, or will it be mounted static?”
Answer: Solar Panels in Florida are required to have a permit and be able to withstand 150 MPH winds, regardless if it is a roof mount or a ground mount array.
This is how I see my PV Side
• The solar array will be permanent in nature, as the County permit requires.
o Though in the event of a hurricane, I will uninstall the two solar panels (2 x +/- 500W Bifacial) and store them in my garage.
• The solar panel frames must be Earth Grounded with two Ground Rods, as per NEC 250 (what I gathered from reading the code)
• The solar panels will be ground wired (6 AWG) to an 8’ Ground Rod approximately 8-10 feet away, which is then tied to my service (grid) Ground Rod that is 10 feet away from the first rod.
This is my system set up, which is exactly as Robbob2112 described.
• Inverter: 12V, 3000W
o Hard Terminal attached to 20A Single Pole Dual Function Circuit Breaker (GFCI & CAFCI) (https://www.amazon.com/dp/B00KHVLZUG?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1)
• Batteries: 3 x 12V 300Ah (900Ah total, 200A BMS)
• Solar Charge Controller: 80A MPPT (handles up to 1200W solar)
• Wiring:
o Split into two legs to manage current:
o One leg handles 350A (for the inverter)
o The other leg handles 300A (for MPPT, fuse box, and 60A AC/DC charger).
This is how I envision my system in operation.
• The system has two sides to it a Battery/Component Side and the PV Side.
• The system Battery/Component Side and the PV Side are easily detached from one another, which allows the Battery/Component Side the ability to:
o Be rolled around to other parts of the house as needed.
o The Cart can also be further broken down into two parts, allowing it to be easily transported, by disconnecting a few wires.
Places I want to be able to transport it to:
- Campgrounds.
- Football tailgates.
- Neighbor’s house whose power has gone out.
How I see the system being grounded in all instances.
• On the PV Side there will be a Dihool Solar Disconnect Switch 40Amp DC Circuit Breaker with Surge Protector PV Combiner Box, which is attached to the Solar Ground Mount Frame.
o From my understanding the ground is separated within the combiner box, which then must be Earth Grounded to two 8’ Ground Rods (PV Ground Rod tied to Service (Grid) Ground Rod (https://www.amazon.com/gp/product/B0C7QR5LD3/ref=ox_sc_saved_image_2smid=A3VVXZCJ717A91&th=1)
• The Battery/Component Side
o When attached to the PV Side for charging and inverter passthrough use.
The 12V 3000W Inverter and 80A MPPT Controller will both be grounded to a Ground Busbar located on the cart.
- This Ground Busbar will have a Quick Connect, which will then be connected to another Quick Connect.
- This other Quick Connect is attached to the Service (Grid) Ground Rod. (See picture below).
o When disconnected from the PV Side and while using the inverter.
The 12V 3000W Inverter and 80A MPPT Controller will both be grounded to a Ground Busbar located on the cart.
- This Ground Busbar will have a Quick Connect, which will then be connected to another Quick Connect.
- This other Quick Connect is attached to the Negative Battery Busbar.
o When disconnected from the PV Side and using the 60A AC/DC Charger.
The 350A Leg (Inverter) Disconnect Switch will be in the manual “OFF” position and the Inverter itself will be turned off.
The 300A Leg (MPPT, fuse box, and 60A AC/DC charger) Disconnect Switch will be in the manual ”ON” position.
The grounding is the same as the grounding in "When disconnected from the PV Side and while using the inverter.".
Again, thank you Robbob2112.
Now to answer your question and rephrase what I am doing, so that you and others can get a better handle on what I am trying to accomplish.
Question - is the array going to be portable as well, or will it be mounted static?”
Answer: Solar Panels in Florida are required to have a permit and be able to withstand 150 MPH winds, regardless if it is a roof mount or a ground mount array.
This is how I see my PV Side
• The solar array will be permanent in nature, as the County permit requires.
o Though in the event of a hurricane, I will uninstall the two solar panels (2 x +/- 500W Bifacial) and store them in my garage.
• The solar panel frames must be Earth Grounded with two Ground Rods, as per NEC 250 (what I gathered from reading the code)
• The solar panels will be ground wired (6 AWG) to an 8’ Ground Rod approximately 8-10 feet away, which is then tied to my service (grid) Ground Rod that is 10 feet away from the first rod.
This is my system set up, which is exactly as Robbob2112 described.
• Inverter: 12V, 3000W
o Hard Terminal attached to 20A Single Pole Dual Function Circuit Breaker (GFCI & CAFCI) (https://www.amazon.com/dp/B00KHVLZUG?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1)
• Batteries: 3 x 12V 300Ah (900Ah total, 200A BMS)
• Solar Charge Controller: 80A MPPT (handles up to 1200W solar)
• Wiring:
o Split into two legs to manage current:
o One leg handles 350A (for the inverter)
o The other leg handles 300A (for MPPT, fuse box, and 60A AC/DC charger).
This is how I envision my system in operation.
• The system has two sides to it a Battery/Component Side and the PV Side.
• The system Battery/Component Side and the PV Side are easily detached from one another, which allows the Battery/Component Side the ability to:
o Be rolled around to other parts of the house as needed.
o The Cart can also be further broken down into two parts, allowing it to be easily transported, by disconnecting a few wires.
Places I want to be able to transport it to:
- Campgrounds.
- Football tailgates.
- Neighbor’s house whose power has gone out.
How I see the system being grounded in all instances.
• On the PV Side there will be a Dihool Solar Disconnect Switch 40Amp DC Circuit Breaker with Surge Protector PV Combiner Box, which is attached to the Solar Ground Mount Frame.
o From my understanding the ground is separated within the combiner box, which then must be Earth Grounded to two 8’ Ground Rods (PV Ground Rod tied to Service (Grid) Ground Rod (https://www.amazon.com/gp/product/B0C7QR5LD3/ref=ox_sc_saved_image_2smid=A3VVXZCJ717A91&th=1)
• The Battery/Component Side
o When attached to the PV Side for charging and inverter passthrough use.
The 12V 3000W Inverter and 80A MPPT Controller will both be grounded to a Ground Busbar located on the cart.
- This Ground Busbar will have a Quick Connect, which will then be connected to another Quick Connect.
- This other Quick Connect is attached to the Service (Grid) Ground Rod. (See picture below).
o When disconnected from the PV Side and while using the inverter.
The 12V 3000W Inverter and 80A MPPT Controller will both be grounded to a Ground Busbar located on the cart.
- This Ground Busbar will have a Quick Connect, which will then be connected to another Quick Connect.
- This other Quick Connect is attached to the Negative Battery Busbar.
o When disconnected from the PV Side and using the 60A AC/DC Charger.
The 350A Leg (Inverter) Disconnect Switch will be in the manual “OFF” position and the Inverter itself will be turned off.
The 300A Leg (MPPT, fuse box, and 60A AC/DC charger) Disconnect Switch will be in the manual ”ON” position.
The grounding is the same as the grounding in "When disconnected from the PV Side and while using the inverter.".
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Absolutely correct… this happens a lot with newer folks……
it’s like reading a “terms of service agreement “ you get from apple when you get some new update or somthing…
We all,sign it it but no one knows what it said…as nobody reads it…
Good call …
robbob2112
Doing more research, mosty harmless
One point about
12.8v x 900ah = 11520Whr
11520Whr / 1200w = 9.6hrs
You need at least twice that amount of panels mounted to charge your batteries in a reasonable amount of time... probably 3 times as many. That also means multiple SCC so you can put the power at the panels to use.
14.4v x 80a = 1152W
So you would need another SCC for each set of 1200w panels.
Each battery has a recommended charge current of 60amps with 200amps max. So putting 3 x 80a chargers would be about right to get them charged in 3.2hrs of full sun.
12.8v x 900ah = 11520Whr
11520Whr / 1200w = 9.6hrs
You need at least twice that amount of panels mounted to charge your batteries in a reasonable amount of time... probably 3 times as many. That also means multiple SCC so you can put the power at the panels to use.
14.4v x 80a = 1152W
So you would need another SCC for each set of 1200w panels.
Each battery has a recommended charge current of 60amps with 200amps max. So putting 3 x 80a chargers would be about right to get them charged in 3.2hrs of full sun.
Yeah was told that early on by Litime after I brought the batteries.
I don't mind that it will take a few days to fully charge the batteries when charging them from the solar panels.
I plan disconnecting the PV Side, when I am using the batteries to power other devices and allow the batteries to drain to 0% as Will suggests in one of his videos. I would then hook the Battery/Component Side back up to the PV Side and recharge the batteries and in the meantime use the grid power like normal
But I have seen a video where the guy hooks up his solar panels to his house's Central A/C outside unit with a micro inverter to supplement the grid power being used. Not going to do it until the guy has it official set up, which he said he plans to do after I contacted him. It was on YouTube and I thought that was pretty cool.
To add when the inspector comes out for the installed Solar Ground Mount, the clerk said they will inspect my system to see if it can be hooked up to the house electric. So I kinda get two inspections done for the price of $90.
So does my grounding look proper.
robbob2112
Doing more research, mosty harmless
Hooking up via microinverter seems ok on the surface until you think about it. AC compressors take a large amount of current to start. So evertime a cloud passes it will stall then if you are lucky there is a delay to the restart. If there isn't a delay the compressor can be damaged over time.
I assumed you wanted to use this for power after a hurricane so rapid recharge in the dreary days after the storm passes would be needed.
So, when you are connected to the pv panels you would get your ground from the EGC.... when you are connected to the house you would get your ground from the house.
You would never connect to both at the same time or you would have a ground loop. To use the pv and be connected to the house you would have the EGC between panels and house and the ground rods at the array disconnected.
To use it elsewhere and not connected to a charging source there would be no ground connected.
The tricky part of this is the N-G bond that is needed someplace... what inverter do you have? Does it provide a N-G bond ? Does it have an outlet on the back ? Does it have direct wire connections?
I assumed you wanted to use this for power after a hurricane so rapid recharge in the dreary days after the storm passes would be needed.
So, when you are connected to the pv panels you would get your ground from the EGC.... when you are connected to the house you would get your ground from the house.
You would never connect to both at the same time or you would have a ground loop. To use the pv and be connected to the house you would have the EGC between panels and house and the ground rods at the array disconnected.
To use it elsewhere and not connected to a charging source there would be no ground connected.
The tricky part of this is the N-G bond that is needed someplace... what inverter do you have? Does it provide a N-G bond ? Does it have an outlet on the back ? Does it have direct wire connections?
The inverter I am using is LITime 3000W Inverter. It has three plugs in front, two UDB, and a 30A Hard Terminal Block. (which is why I using a 20A GFCI breaker.
"1 Hack To Eliminate Your A/C Power BIll This Summer!" that is the name of the video on YouTube. Watch it and let me know what you think.
The below might be me just rambling, as I am extremely tired at the moment. If it doesn't make sense just say so. As it was hurting my head by the time I finished.
Ok Back to Topic.
In my scenarios my PV Side solar frames have a ground wire that goes along with the P+ and P- into the pre-wired Combiner Box and then I just connect the 3 wires to their designated spots. This Combiner Box has a disconnection switch, surge protection, water resistance, and protects against lighting strikes (Definitely need in Florida), which outputs the P+, P-, and Ground Wire on the other side, The P+ and P- wires are then connected to the MPPT Controller to charge the batteries, while the Ground Wire is connected to an 8' Grounding Rod more than 6 feet away from the solar array. This setup is all i have seen in other videos, where the PV Sidse is permanent.
1) I think you are saying that if i use the FPL Service Rod as my first Grounding Rod, I then need to tie that to a second Grounding Rod.
This is how i am interpreting NEC 250, where it says that unless you can prove the Ohms of the first Grounding Rod, you must then use a second Grounding Rod to pass inspection. OR
2) Do I connect the Grounding Wire from the Combiner Box to an 8' Grounding Rod, which is tied to a second Grounding Rod that is not attached to anything else. OR is the second ground bar not necessary if the Battery/Component Side isn't grounded to the First Grounding Rod.
Regardless of above scenarios, what am I doing in the Battery/Component Side as far as grounding?
A) Do i connect the grounding screw on the MPPT Controller to MPPT Controller Chassis and the Inverter ground screw to the Inverter Chassis? (Which sounds like a double bond to me), OR
B) Do I just connect both device's grounding screw separately to a "Ground Busbar"
Now if I do B) do i connect that Ground Busbar to
1) The "Negative Battery Busbar" (Which I would do if the Battery/Component Side is being wheeled around), Or
2) The First Grounding Rod that the PV Side is grounded to.
************
"You would never connect to both at the same time or you would have a ground loop. To use the pv and be connected to the house you would have the EGC between panels and house and the ground rods at the array disconnected."
If i understand this paragraph correctly (And i think I am starting to visualize everything). I can connect both the PV Side "Array Grounding Wire" and The Battery/ Component Side "Ground Busbar Wire" to the FPL Service Ground Rod, which is then tied to a second Ground Rod that goes nowhere.
If I did what i said in my previous post.
Where i had the PV Side connected to an 8' Ground Rod, which then is tied to the FPL Service Ground Rod. I would in fact be creating a Ground Loop, even if i didn't connect my Battery/Component Side to the FPL Service Gound Rod. That this Ground Loop is actually created when you have equipment connected to both Ground Rods that are tied together and that even if the Rods are not tied together,i would still be creating a Ground Loop.
That the only way to prevent this Ground Loop is to have a First Ground Rod that everything is connected to while the second is only tied to the first Ground Rod.
Now all i really need to know is can I use the FPL Service Ground Rod or not.
"1 Hack To Eliminate Your A/C Power BIll This Summer!" that is the name of the video on YouTube. Watch it and let me know what you think.
The below might be me just rambling, as I am extremely tired at the moment. If it doesn't make sense just say so. As it was hurting my head by the time I finished.
Ok Back to Topic.
In my scenarios my PV Side solar frames have a ground wire that goes along with the P+ and P- into the pre-wired Combiner Box and then I just connect the 3 wires to their designated spots. This Combiner Box has a disconnection switch, surge protection, water resistance, and protects against lighting strikes (Definitely need in Florida), which outputs the P+, P-, and Ground Wire on the other side, The P+ and P- wires are then connected to the MPPT Controller to charge the batteries, while the Ground Wire is connected to an 8' Grounding Rod more than 6 feet away from the solar array. This setup is all i have seen in other videos, where the PV Sidse is permanent.
1) I think you are saying that if i use the FPL Service Rod as my first Grounding Rod, I then need to tie that to a second Grounding Rod.
This is how i am interpreting NEC 250, where it says that unless you can prove the Ohms of the first Grounding Rod, you must then use a second Grounding Rod to pass inspection. OR
2) Do I connect the Grounding Wire from the Combiner Box to an 8' Grounding Rod, which is tied to a second Grounding Rod that is not attached to anything else. OR is the second ground bar not necessary if the Battery/Component Side isn't grounded to the First Grounding Rod.
Regardless of above scenarios, what am I doing in the Battery/Component Side as far as grounding?
A) Do i connect the grounding screw on the MPPT Controller to MPPT Controller Chassis and the Inverter ground screw to the Inverter Chassis? (Which sounds like a double bond to me), OR
B) Do I just connect both device's grounding screw separately to a "Ground Busbar"
Now if I do B) do i connect that Ground Busbar to
1) The "Negative Battery Busbar" (Which I would do if the Battery/Component Side is being wheeled around), Or
2) The First Grounding Rod that the PV Side is grounded to.
************
"You would never connect to both at the same time or you would have a ground loop. To use the pv and be connected to the house you would have the EGC between panels and house and the ground rods at the array disconnected."
If i understand this paragraph correctly (And i think I am starting to visualize everything). I can connect both the PV Side "Array Grounding Wire" and The Battery/ Component Side "Ground Busbar Wire" to the FPL Service Ground Rod, which is then tied to a second Ground Rod that goes nowhere.
If I did what i said in my previous post.
Where i had the PV Side connected to an 8' Ground Rod, which then is tied to the FPL Service Ground Rod. I would in fact be creating a Ground Loop, even if i didn't connect my Battery/Component Side to the FPL Service Gound Rod. That this Ground Loop is actually created when you have equipment connected to both Ground Rods that are tied together and that even if the Rods are not tied together,i would still be creating a Ground Loop.
That the only way to prevent this Ground Loop is to have a First Ground Rod that everything is connected to while the second is only tied to the first Ground Rod.
Now all i really need to know is can I use the FPL Service Ground Rod or not.
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robbob2112
Doing more research, mosty harmless
I am assuming you are talking about this unit?
This one only powers a load and draws energy from the battery - no charging
Or this?
This one can draw energy from the grid to charge or power loads - it is NOT meant to have the output connected back to the grid in any way, and if you do you will damage it and possibly things attached to the grid.
To power loads during an outage you need to either use extension cords or a critical load panel.
It does the N-G bond inside the unit so you don't need to worry about that except that you would not want to have it connected at the same time a bonded generator is connected.... even if the generator is off the N-G bond there would cause damage to other stuff on the circuit and probably the inverter.
You cause confusion because you want to run from PV only or connected to grid to charge or just tailgating
Tailgating - you have no ground - it floats - no charge source
Connected to grid for charging - the ground comes from the grid.
Connected to PV panels only you have an EGC from the array connected to the MPPT and to the inverter and if the cart is metal it too.
Connected to both PV and grid you need to disconnect the ground rods at the array - so just dont run this way, EVER.
Leave the combiner connected to the rods there and to the panel frames -
the inverter and mppt screws are tied together.... the MPPT isn't used when you are plugged into the grid.... the grid isn't used when you are plugged into the PV panesl.
You connect the panel frames to the ground rods out at the array and to the combiner --- you may want to consider using 10/2 SOW or 12/2 SOW cable for your PV so you have white/black/green wires inside it - just make sure it is rated above your array voltage. Then you could use powerpole connectors to do the connections
You can have a charge source of the PV array or you can have a charge source of the grid - you would NEVER run both at once - it complicates things...
The two ground systems are independant - they will never be connected at the same time - the answer would be different if the inverter was hard wired to the house - but it is on a cart so never connect to both charging sources at the same time.
You do NOT want to connect the two grounding system or any nearby lightning strike would induce a voltage gradient in the ground ... enter one rod go through your equipment and exit the other rod....
SO - for wiring - the plug on the back will do 15 amps ... if you want to use more power you would need to pigtail a power strip or outlets to the hard wired AC out points.
You would use a wire with a plug hardwired to the back to plug into the grid. You would only do this to charge the battery, not to run loads... so it would be simplest to get a plug from home depot with the wires bare on one end. Use ferrules on the wires - it gathers the strands so they can be clamped in good.
The battery cables -
3000/12.8 * 1.25 = 292 amps
See the charts below - I generally try to use the NEC table for a starting point and will shift to the welding wire tables at 105c if I need smaller cables, but that means the cable may get warm or hot so you need to take that into account.
the 60c tables say 250mil cable - one size up from 4/0 - or 2 x 2/0 cables is the same cross-section area.
Using the welding wire table at 105c table you are looking at 2/0, but I would use 4/0 to keep it cool. I wouldn't actually run at max 3000w so just 4/0 is fine and you fuse it for that.
cable charts
I got the first LiTime 12V 3000W Inverter you mention, not the second one. Which I am glad i didn't get as I've seen videos where it is not that good.
I will read your other comments later tonight or tomorrow. Thank you so much. This grounding part of the project is just racking my brains. I am actually going to read NEC 690, like I did NEC 250, hopefully I can clarity after reading the rest of your post and the NEC article.
Love the RUSH reference in your screen name, if that is what it is.
Have a Great Weekend.
I will read your other comments later tonight or tomorrow. Thank you so much. This grounding part of the project is just racking my brains. I am actually going to read NEC 690, like I did NEC 250, hopefully I can clarity after reading the rest of your post and the NEC article.
Love the RUSH reference in your screen name, if that is what it is.
Have a Great Weekend.
robbob2112
Doing more research, mosty harmless
So, with the first inverter it is much simpler -
When tailgating you just use the outlet - no ground - the output floats
When charging from the array you just connect the EGC to the MPPT and inverter ground screws
When using it to power something in the house you just plug that into the outlet on the back or an extension cord and pretend you are tailgating
When tailgating you just use the outlet - no ground - the output floats
When charging from the array you just connect the EGC to the MPPT and inverter ground screws
When using it to power something in the house you just plug that into the outlet on the back or an extension cord and pretend you are tailgating
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