Semi off grid with grid tide assistance.

[Matt Matt]

I have purchased 31 X 555 W panels, two 2000 W wind turbines that are 240 V three phase and the step down charge controller, 2 Chinese (but aren't they all Chinese) 10,000 W inverters, and two 200 amp 48 V batteries. The inverters are grid tied, off grid, or all in one solar charge inverter. From my research it's very similar to the grow watt. It does have parallel connection and three phase parallel connection. It also has in the programming isolation from ground and connection to ground.

My main question is how many people are using a three legged L1 L2 neutral disconnect, between the main panel and the generated panel that has the solar, the batteries, the wind turbines.....

I fully understand the floating ground versus neutral ground at the inverter. This inverter does not have that problem with a ground screw like some grow watts.

This inverter can be set to automatic pass-through keeping the ground and neutral separate and, during battery or solar input, the neutral is floating.

The manufacture stated, this is and needs to be programmed whether this is the primary source or the secondary source. Is this in a motorhome or does this go back to a grid tide main panel where neutral and ground are tied.

It can be parallel connected up to six units, or 60,000 W.

 

[Hedges]

Mobile systems isolate neutral from shore power, and locally bond N to G.

Some grid systems in places like Japan use a 3-pole RCD to isolate everything.

In the US, grid + backup, I keep neutral (and ground) connected all the time, and use the N-G bond in my main panel at utility meter.

I've been using a 2-pole disconnect. Some I've bought for new installations are 3-pole, and I may use the 3rd pole to trigger rapid-shutdown if I have a battery backup system. (otherwise, simply opening L1/L2 shuts of grid tie inverters and triggers RSD.)

If your system is grid-backup and if the inverters are 230V not split-phase, so you use an auto-transformer, then you may have some neutral and ground issues. If your inverter and your grid connection are both same type, no auto-transformer needed, you should be fine.

But if grid connected, I hope the equipment has proper listings (we use UL in the US.)

 

[Matt Matt]

The inverters I bought are 240 V split phase inverters which have L1, L2 N,G. Input, and the same as the output. They also can be configured for only 120 V input with 120 V output, but this would be at double the amperage.

But these can be paralleled to six units total.

Each unit can provide about 5000 W per leg to neutral . This is with the floating neutral or 10,000 W at 240 V.

This unit can also be set up on a camper trailer as the main distribution and can have the neutral ground bond. But this is not what I'm looking for. What I'm looking for, how many people disconnect their neutral from the mains to the inverter to prevent at lineman shock by backfeeding neutral??

 

[Hedges]

Neutral is bonded to ground at first disconnect after utility meter. No backfeed or shock hazard.

On L1 and L2 there would be the potential to backfeed. All my inverters (except an offgrid StatPower) have UL-1741 anti-islanding so are designed and listed to disconnect when grid goes down.

I also have visible blade disconnect for L1/L2.

I think the only time people use neutral disconnect is for mobile applications, or other countries having a different grid configuration and grounding system (e.g. "TT")

Are your inverters designed to backfeed the grid for net metering? To add power in parallel (assist) but not backfeed? Or, are they designed to isolate from grid before operating as inverter?

I would not trust any that backfeeds or operates in parallel with grid unless it had UL (or whatever your local) listing.
It sounds like yours may be configurable for either on or off-grid use. But like I said, I wouldn't trust it without NRTL certification/listing.

 

[timselectric]

I fully understand the floating ground versus neutral ground at the inverter.

I'm not sure that you do.

Because of this statement.

This inverter can be set to automatic pass-through keeping the ground and neutral separate and, during battery or solar input, the neutral is floating.

That's the opposite of what you want to happen.
Any AIO with pass through function should be capable of dynamic bonding.
Which means that it disconnects its internal bonding relay in pass through and uses the source bond. Then connects its bonding when not in pass through.

This inverter does not have that problem with a ground screw like some grow watts.

This has to do with using a European Growatt (or any manufacturers) inverter in North America.

 

[Matt Matt]

It has one of these stickers on the side. It says it’s CSA approved.

 

[Matt Matt]

That's the opposite of what you want to happen.

But, I have a Honda gas generator. And it also has a floating neutral. I plan on running this in parallel. How would you suggest to kill any neutral back feed to the grid?? In an ideal situation all power should return to its source, but what if it doesn't? Could power return to the grid through the neutral??

Another question, do you have a quick shut down for solar and battery back up at your main meter? Can you show me some pictures please? As well, how did you implement your wind turbines with your system? Do you have a quick shut down? thank you.

 

[billvon]

But, I have a Honda gas generator. And it also has a floating neutral. I plan on running this in parallel. How would you suggest to kill any neutral back feed to the grid?? In an ideal situation all power should return to its source, but what if it doesn't? Could power return to the grid through the neutral??

Another question, do you have a quick shut down for solar and battery back up at your main meter? Can you show me some pictures please? As well, how did you implement your wind turbines with your system? Do you have a quick shut down? thank you.

So neutral won't backfeed. It goes to ground at the service entrance. There is no way for that current to get back to the grid.

To avoid backfeeding on the grid input you can do several things:
1) Go off grid and completely disconnect. Only reconnect when your batteries are low and you want to recharge.
2) Do a "net zero" install, where current sense transformers ensure you never backfeed. This works 99.9% of the time.
3) Do a "net small" install, where current sense transformers ensure you are always taking a small amount of current. This will tend to eliminate accidental exports due to control loop speed.

I have the usual AC disconnect for my solar array. No quick shutdown for battery.

 

[timselectric]

But, I have a Honda gas generator. And it also has a floating neutral.

It should. Because your system already has a N/G bond. (There can only be one)

I plan on running this in parallel.

You can't do that. Unless your inverter is capable of syncing with a generator without damaging it. (Absolutely no exporting to generator)

How would you suggest to kill any neutral back feed to the grid??

That's not a thing.
Current only flows in a completed circuit. (Circle)
Current can't flow with only a single point of connection.

In an ideal situation all power should return to its source

In any situation, it can only return to its source.

but what if it doesn't?

Current won't flow, without a path.

Could power return to the grid through the neutral??

Yes, if it originated at the grid.
Or you connect a separate source to the grid (minimum of two conductors)

Another question, do you have a quick shut down for solar and battery back up at your main meter?

No
Maybe, in the future.

As well, how did you implement your wind turbines with your system?

No turbines here. Not worth it for my location.

 

[Matt Matt]

No turbines here. Not worth it for my location.

You would be very surprised. At my summer home I can generate over 6000 W per day with my old wind 500 W when generators. Some small generators can give 500 to 1000 W. My wind new generators are pretty big. The fan is just over 10 feet diameter. The power from the wind generators has got me onto the solar generators and more batteries. I only have 20 foot towers, but they are situated Lakefront which I get crazy winds. Some days I can produce 2000 W and some days I can produce 50,000-72,000w. But, on super windy days most of this is getting dumped into heat outside. This is why I am investing more in solar and all in one inverters and batteries. I want to capture more than just the wind. And, using it for battery, than just heating the outside. And, yes I have considered using the extra heat to heat my hot water tank. But I don't want to mix my AC with DC, hence the all in one inverters. I already have my hot water tank set up in two different heating electrodes. So now what I'm going to do is dump my plateau into my hot water tank lower heat electrode instead of dumping the heat outside with the inverters.