Last check for ground plan of my offgrid system

[sunsurfer]

.... By not grounding the array, you will increase the chances of someone getting hurt.

I don't want to hijack this thread but could you comment on the dangers of non grounded arrays?

 

[timselectric]

Thank you timselectric. I understand and agree with you. I need to investigate why in Aruba we don’t bound ground and neutral at the first means of disconnect. My 3 phases wires go from the street meter directly to my principal panel which to me is my first means of disconnect. When I changed the panel last week I was surprise to see that the neutral was not bond to the ground. Tomorrow I will reach out to local electricians and investigate why?

Generally in parts of the world (other than North America). The N/G bond is provided by the utility company. This is easy to determine by checking if the utility provides you with a ground conductor, along with the service conductors.

 

[timselectric]

I don't want to hijack this thread but could you comment on the dangers of non grounded arrays?

The grounding systems purpose is to provide a low impedance (resistance) path for fault current.
This is so that a fault can quickly blow a fuse or trip a breaker. To clear the fault before someone gets hurt.
Any exposed conductive parts that aren't grounded. Can become energized without any indication of the Hazzard. And then if someone touches it, can be hurt or killed.
This is why we ground any exposed conductive parts. To keep them safe to touch.

 

[glandpuck]

The grounding system begins at, and is created by the N/G bond. This is either done at the grid service first means of disconnect. Or provided by the utility provider. To ground something electrically, means connecting it to this grounding system. (As in your drawing)

Driving a separate ground rod and connecting anything to it. Doesn't ground it. It only connects it to earth.

The bonding between neutral and the ground is from the utility company at your main panel. This creates in a 3 phase system I believe your L1/L2and L3 hots with a neutral and a ground. Because of the bonding, the reference voltage of the neutral should be 0 volts. The neutral and hots complete your circuit. the ground wire is used to protect from electric shocks. for example, any metal electric boxes, motors, etc are grounded so as not to produce an electric shock if contacted.

The bonding between neutral and the ground is from the utility company at your main panel. This creates in a 3 phase system I believe your L1/L2and L3 hots with a neutral and a ground. Because of the bonding, the reference voltage of the neutral should be 0 volts. The neutral and hots complete your circuit. the ground wire is used to protect from electric shocks. for example, any metal electric boxes, motors, etc are grounded so as not to produce an electric shock if contacted.

Separately grounding the array and combiner box provides the fastest, quickest path for a lightening strike to dissipate a massive amount of electricity. You certainly do not want this connected to a water pipe and then surging thru your home.

If a grounding rod cannot be inserted into the earth straight down, then there are other means such as laying horizontally in a concrete covered ditch. Concrete is an excellent conductor of electricity and helps dissipate electricity very well. Consult a local for more on your situation.

As for lightening arrestors, I personally use Delta brand, but Midnite Solar also makes an excellent unit, but the cost is definitely higher. Both are effective. They attach to the +, - and ground in the combiner box. Contact them for how to connect to a three phase subpanel.

 

[jimmy747]

The bonding between neutral and the ground is from the utility company at your main panel. This creates in a 3 phase system I believe your L1/L2and L3 hots with a neutral and a ground. Because of the bonding, the reference voltage of the neutral should be 0 volts. The neutral and hots complete your circuit. the ground wire is used to protect from electric shocks. for example, any metal electric boxes, motors, etc are grounded so as not to produce an electric shock if contacted.

Separately grounding the array and combiner box provides the fastest, quickest path for a lightening strike to dissipate a massive amount of electricity. You certainly do not want this connected to a water pipe and then surging thru your home.

If a grounding rod cannot be inserted into the earth straight down, then there are other means such as laying horizontally in a concrete covered ditch. Concrete is an excellent conductor of electricity and helps dissipate electricity very well. Consult a local for more on your situation.

As for lightening arrestors, I personally use Delta brand, but Midnite Solar also makes an excellent unit, but the cost is definitely higher. Both are effective. They attach to the +, - and ground in the combiner box. Contact them for how to connect to a three phase subpanel.

Thank you Tim and Glandpuck for taking the time to explain everything so clearly. I don't see a ground coming from the utility company so I will investigate. I agree with you that is better to ground the array separately. Again more to investigate how to do it here. At 8 AM I will hit the road, investigate and report back with the forum to verify the information I collected. Thank you all again for precious information.

 

[timselectric]

Separately grounding the array and combiner box provides the fastest, quickest path for a lightening strike to dissipate a massive amount of electricity. You certainly do not want this connected to a water pipe and then surging thru your home.

It's not grounded if it's separated from the grounding system.
This is electrical grounding, not lightning protection. That's a completely different system.
Which is never connected directly to what you want to protect.

 

[glandpuck]

It's not grounded if it's separated from the grounding system.
This is electrical grounding, not lightning protection. That's a completely different system.
Which is never connected directly to what you want to protect.

Actually, grounding is protection from electrocution. The cause, whether it be from a utility source of current or a lightening strike results in the same effect to different degrees. The point of "grounding" is to find the easiest pathway for electricity to flow and to prevent it from flowing through flesh whenever possible.

Grounding of the utility source of electricity is a priority since it is always present. Grounding from a lightening strike is prevention since it is not always present.

 

[jimmy747]

Well very interesting learning day here in Aruba. I talked to a line worker at the utility company. I asked why from my meter to my house I only see 4 wires L1 L2 L3 N. No ground. He said because the Neutral is ground. So just like timselectric suggested, in my case the bonding is done at the utility company. Houses built before 2014 (mine) that have an electrical panel grounded to the water pipe are ok and pass inspection. Then I called a solar company here in Aruba. I asked if an external grounding rod is necessary. He said they ground the array, inverter everything to the house ground. In my case that means to the ground in the main panel that goes to a water pipe. If my solar system would consist of panels and batteries and no connection whatsoever to my house electrical I would simply put a separate ground rod. BUT because the inverter can use some electricity from the utility company, then the Growatt instructions clearly state connect hot, neutral, AND GROUND to a 40A breaker in my main panel. (like in this picture). WHat if I do not connect that ground wire? Just a thought. I feel I made great progress but I am not 100% sure that is the correct and safe way. Thoughts? Thank you all for your help.

 

[timselectric]

Connect the ground conductor to the existing grounding system at the main panel.
Just like your picture shows.

 

[timselectric]

So, back to my other concern.
You have a 3-phase wye system. (L1, L2, L3, N, G) not sure of your voltages.
The Growatt SPF-5000-ES is a single phase 230v system. (L1, N, G)
Your load (A/C) is 230v. But is it L, N, G or L1, L2, G ?
A 2 pole breaker suggests L1, L2, G.

 

[jimmy747]

So, back to my other concern.
You have a 3-phase wye system. (L1, L2, L3, N, G) not sure of your voltages.
The Growatt SPF-5000-ES is a single phase 230v system. (L1, N, G)
Your load (A/C) is 230v. But is it L, N, G or L1, L2, G ?
A 2 pole breaker suggests L1, L2, G.

Sorry Tim I did not answer that. Right now I am investigating your concern and I will reply later. Thank you. Excellent point.

 

[jimmy747]

Sorry Tim I did not answer that. Right now I am investigating your concern and I will reply later. Thank you. Excellent point.

Hello Tim, I went to an electrical company to discuss this. So all my ACs are currently connected to double breakers L1 L2 GND. They confirmed that here in Aruba we connect european inverter (which is what I have) L1 L2 GND. Here L1 and N produce 127V. L1 L2 give us the 230 V. So I believe I will be ok. What do you think? Thank you.

 

[timselectric]

Hello Tim, I went to an electrical company to discuss this. So all my ACs are currently connected to double breakers L1 L2 GND. They confirmed that here in Aruba we connect european inverter (which is what I have) L1 L2 GND. Here L1 and N produce 127V. L1 L2 give us the 230 V. So I believe I will be ok. What do you think? Thank you.

The Growatt's output is 230v L, N, G.
It bonds neutral with ground internally, when it's running on battery.
You can open it up and defeat the bonding. In order to be able to run it on L1 and L2. But then it wouldn't have any ground on the output, when running on battery. And wouldn't have any ground fault protection or detection.
It's not designed for this type of grid system.

 

[jimmy747]

The Growatt's output is 230v L, N, G.
It bonds neutral with ground internally, when it's running on battery.
You can open it up and defeat the bonding. In order to be able to run it on L1 and L2. But then it wouldn't have any ground on the output, when running on battery. And wouldn't have any ground fault protection or detection.
It's not designed for this type of grid system.

Thank you Tim, I am quite impressed with your knowledge of the product. At the same time disapointed by the Growatt manufacture who supposely review my diagram and told me it would be fine as is. I understand what you said. A reputable electrical firm told me to just connect
L1 to L and L2 to N. What would happen if I do that? Thank you again. your help is greatly appreciated.

 

[timselectric]

Thank you Tim, I am quite impressed with your knowledge of the product. At the same time disapointed by the Growatt manufacture who supposely review my diagram and told me it would be fine as is. I understand what you said. A reputable electrical firm told me to just connect
L1 to L and L2 to N. What would happen if I do that? Thank you again. your help is greatly appreciated.

I've been using the same units for almost 2 years. I'm very familiar with them inside and out. And how they operate in all scenarios.
As I stated before. The Growatt bonds it's output neutral and ground together. This will have to be defeated, in order to connect it to L1 and L2.
The problem is that you lose ground on the output, when it uses battery for power. I can't recommend running without a ground.
I'm using an autotransformer to create my ground.

 

[jimmy747]

I've been using the same units for almost 2 years. I'm very familiar with them inside and out. And how they operate in all scenarios.
As I stated before. The Growatt bonds it's output neutral and ground together. This will have to be defeated, in order to connect it to L1 and L2.
The problem is that you lose ground on the output, when it uses battery for power. I can't recommend running without a ground.
I'm using an autotransformer to create my ground.

Good morning Tim. Totally agree with you Safety first so with my coffee I’ll start searching and learning how to create ground with an autotransformer. Thank you.

 

[timselectric]

Good morning Tim. Totally agree with you Safety first so with my coffee I’ll start searching and learning how to create ground with an autotransformer. Thank you.

To clarify.
The autotransformer creates a center tap. Normally used for neutral. This tap is then used for grounding. Basically it is a N/G bond, without actually using the neutral aspect of it.

 

[jimmy747]

To clarify.
The autotransformer creates a center tap. Normally used for neutral. This tap is then used for grounding. Basically it is a N/G bond, without actually using the neutral aspect of it.

Wow! Very clever! I know some electrical but I am not an expert like you. However, I do read pictures very well! Could you share an electrical diagram of your installation? That would help me a lot. Maybe someday you visit Aruba and check out my solar installation you helped me design!
Thank you Tim.

 

[timselectric]

This is an autotransformer. In our case, we are using the center tap (neutral) for the ground. This gives you a grounding point for the system. Without causing a short on one of the lines.

 

[hwy17]

whether it be from a utility source of current or a lightening strike

Grounding is not for lightning protection. NFPA has a whole separate book on that.