Best wiring sequence for mobile install of Growatt 3000 24V

[Aakelley]

I purchased the bundle that Signature Solar was selling over the holidays. It has a Growatt 3000 24V, 2 of their EG4 24v 200 AH server rack batteries and 10x 265W panels. I purchased it to add solar to my skoolie. I‘ve been doing some test assemblies in my workshop before the real install and reading / watching as much as I can on the inverter and the batteries. This forum has been a great resource - thank you all!

I will probably have a few questions as I go, but here is the first: since my skoolie is setup for 30 Amp Service and the generator I bring along is only a 3500 watt predator, would it make more sense to wire the Growatt and shore power into a transfer switch and then into panel rather than having power run through the Growatt and then into the panel? I know I would be bypassing the shore power charger in the Growatt in this case, but given the power constraints (yes, I could upgrade the shore power service to 50 amp and buy a bigger generator - question is in the context of what I have in place) it seems to me it might be a better way to go.

I do have a seperate battery charger from Signature Solar so if I was on shore power / generator and wanted to charge the battery / wasn’t using much other power I could.

 

[Aakelley]

I suppose if I do wire up shore / generator power through the growatt, I can just actively manage my power usage through the distribution panel.

Just wondering if there is a pro / con to either that I’m not considering. Truly seems like a coin toss as I think about it.

 

[John Frum]

The growatt includes an automatic transfer switch so the most orthodox setup is...

ac_distribution_panel {
    |<-master_breaker<-growatt<-surge_protector<-inlet<-generator
    |->branch_breaker_1
    |->branch_breaker_2
    |->branch_breaker_...
}

The most important thing to consider is safety.
There needs to be 1 and only 1 neutral/ground bond in every mode of operation.
There is much confusion regarding Growatt all_in_ones in this regard.
@FilterGuy has been working on this issue maybe he can help us.

The modes of operation are...
1. ac bypass
1.1 connected to shore power
1.2 connected to generator
2. inverter(not connected to shore power or generator)

@FilterGuy I would guess the generator should have a n/g bond via a bonding plug for this use case, is that what you suggest?

 

[Aakelley]

Thanks for the feedback. I have read a lot (here mostly) about the n/g bond and approaches to it via an external relay. I studied the download provided on how to do it specifically for the Growatt, so think I have a good enough handle on that (I know that good enough isn't really when it comes to grounding...but it also seems to me that even experience electricians have a hard time with n/g for mobile situations with multiple different sources.

What I am reading from your reply above is that it is possible to configure the grow watt to never charge the batteries from the internal charger? If so, then I understand and agree. The video that prompted my question was from Signature Solar on the Growatt 3000. I think they pretty clearly recommend against using the integrated AC battery charger on generator since you need such a large one (which again, I don't have in my mobile setup). I think the main concern was that you needed to account for the power needed for the loads as well as the power needed for the battery charger. If I can configure it to bypass only (never use shore power of any form for battery charging), then I understand the suggestion and agree.

(EDIT: Spelling)

 

[John Frum]

I think I misunderstood your question.
I think this video might answer the question you are asking.

 

[John Frum]

Thanks for the feedback. I have read a lot (here mostly) about the n/g bond and approaches to it via an external relay. I studied the download provided on how to do it specifically for the Growatt, so think I have a good enough handle on that (I know that good enough isn't really when it comes to grounding...but it also seems to me that even experience electricians have a hard time with n/g for mobile situations with multiple different sources.

What I am reading from your reply above is that it is possible to configure the grow watt to never charge the batteries from the internal charger? If so, then I understand and agree. The video that prompted my question was from Signature Solar on the Growatt 3000. I think they pretty clearly recommend against using the integrated AC battery charger on generator since you need such a large one (which again, I don't have in my mobile setup). I think the main concern was that you needed to account for the power needed for the loads as well as the power needed for the battery charger. If I can configure it to bypass only (never use shore power of any form for battery charging), then I understand the suggestion and agree.

(EDIT: Spelling)

I'm not very familiar with the Growatt units but hopefully you can configure the ac charge current so that your generator can service your ac loads and provide some charge current to the batteries.

 

[Aakelley]

I think I misunderstood your question.
I think this video might answer the question you are asking.

Yep - that was the video that triggered my question.

 

[drwoods]

I have a Growatt SPF 3000TL LVM-ES. Setting 02 controls the limits on overall charging amps. Setting 011 in this unit provides for limiting the AC charging amps (or generator), effectively allowing you to control the demand placed on the AC (or generator) input. I'm not familiar with your Growatt unit, but you might check if your settings offer the same AC charging limitations.