Confused About Grounding Array

[inky]

I have an MPP Solar U5648MS inverter (manual here) and 8x second hand ET-M660280WB 280W panels (datasheet here) and I'm not entirely sure what to do about grounding.

I think I'm confusing earth and ground here, but in the inverter manual it says:

WARNING: Because this inverter is non-isolated, only three types of PV modules are acceptable: single crystalline, poly crystalline with class A-rated and CIGS modules. To avoid any malfunction, do not connect any PV modules with possible current leakage to the inverter. For example, grounded PV modules will cause current leakage to the inverter. When using CIGS modules, please be sure NO grounding.

I can't see anything about grounding on the panel datasheet, but my understanding is I should connect the panels/rails to the main earth rod that is pounded into the dirt next to my cabin right? This stops lightning from destroying my equipment?

Sorry for what I'm sure is an elementary question.

 

[12VoltInstalls]

I think I'm confusing earth and ground

Ground and earth should be the same thing. Solar panels have a negative cable, neg(-), while a ‘ground’ is not that negative cable.

Others will have to answer machine specific because I don’t know the unit

 

[wmgeorge]

Interesting, but are they talking about Grounding the (-) or Negative wire or grounding the metal frame of the panel?

 

[solarsimon]

You are earthing your frame, not the actual PV part, which sits inside a glass casing

 

[inky]

You are earthing your frame, not the actual PV part, which sits inside a glass casing

So it's totally fine for me to earth the frame? I assume they are talking about not earthing the ground (-) which I wouldn't anyway because it's a DC circuit, which has a floating earth/ground... ?

 

[wmgeorge]

I also think grounding the frame and any metal is Code.

 

[12VoltInstalls]

I also think grounding the frame and any metal is Code.

…in some jurisdictions they enforce either gridtie or offgrid -or both- being ‘grounded’ back to the/a system earth/dirt ground rod.
A) there are a number of threads here discussing this from the last few months
B) there is an NEC page reference specific to this and a Mike Holt video covering it as well.

So it's totally fine for me to earth the frame?

The remote ground mount panel mounting frame ‘dirt’ ground rod is there for lightning; NFPA discusses that but not NEC @timselectric

I assume they are talking about not earthing the ground (-) which I wouldn't anyway because it's a DC circuit, which has a floating earth/ground...

NO. The panels have a pos(+) and neg(-) conductor. That IS a circuit but is not a ground.

Ground and earth should be the same thing. Solar panels have a negative cable, neg(-), while a ‘ground’ is not that negative cable.

Let me rephrase:
“Ground” and “earth” should be terms that mean the same thing for AC wiring. In DC solar equipment circuits we (confusingly) refer to the negative conductor of the battery and the central connection of the DC negative cables (busbar, batt neg(-)) interchangeably as earth (European) and/or ground (North American).
I have taken to include referencing ‘dirt’ for mention of a/the driven ground rod of a system’s safety grounding termination point because of this.
The DC circuit negative(-) is not really a floating ground as it always winds up at the system neg(-) connection which is its tie; it would not be circuit without it so not a “floating ground” because it is the negative conductor. Further, ‘dirt’ should never wind up being a part of the designed DC circuit.

You are earthing your frame, not the actual PV part, which sits inside a glass casing

Exactly

also think grounding the frame and any metal is Code.

And further: roof/building mounts require that but in a different fashion, and sometimes jurisdictionally variable.

 

[Jamielt55]

Hello, I have a ground mounted array attached to an 8 foot long/deep ground rod and I ran a 6 gauge ground wire out to it that ties to a second 8 foot long/deep ground rod near the garage. Will this creat a ground loop? The array mounted on wood posts set in concrete, no metal.

I plan to connect a Giandel 3000 watt (psw) inverter to a non boned breaker box.

 

[12VoltInstalls]

What is your purpose of two ground rods?

have a ground mounted array attached to an 8 foot long/deep ground rod and I ran a 6 gauge ground wire out to it that ties to a second 8 foot long/deep ground rod near the garage

The frames of the array should be grounded at the array imho, but code apparently says it needs to run back to entrance panel’s ground rod.

plan to connect a Giandel 3000 watt (psw) inverter to a non boned breaker box.

So the chassis of the Giandel is connected to the ground rod.
I’m assuming that you have zero volts between Giandel L and G, And zero continuity between chassis ground and N?

Contact Giandel to make sure but I believe you should have a N-G bond in your panel if this is 100% off grid. All G/bare and N’s should only meet in one place and should meet there.

 

[Jamielt55]

What is your purpose of two ground rods?
Answer: When I installed the solar panels on the wood structure I installed the first ground rod. I watched a YouTube video that suggested the two ground rods.

 

[RV10flyer]

I also install a MNS SPD600 on every string. Then my panels, unistrut and SPD's go to a ground rod at the array. I hope to keep the lightning out there 100' from inverters.

 

[12VoltInstalls]

When I installed the solar panels on the wood structure I installed the first ground rod. I watched a YouTube video that suggested the two ground rods.

I wouldn’t go by most youtube videos. If any. I would go by this series. Here is the first epistle: https://diysolarforum.com/resources/grounding-made-simpler-part-1-ac-houshold-grounding.157/ and the third in the series covers your panels b