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This reminds me of some Schneider inverters that I worked on a couple of years ago. we had 3 inverters in parallel each rated at 60A pass-thru current. We burned up the transfer relay in one of the units. After doing some research I found this document.

I want support to connect to multiple Batteries My battery bank has 4pc EG4LL with LCD batteries and 2pc EG4 LIFEPOWER4 without LCD. I can connect to the EG4LL or the LIFEPOWER4 but not both at the same time. It would be great if we could pick multiple batteries on the configuration page.

I think you need to use 120V coils on your "Lost N Contactors" if you plan on wiring them in series as shown on your last schematic.

Why did you change your "Lost N contactor" to switch both L1 and L2 on each contactor instead of one contactor switching L1 and the other switching L2 as you had it previously? I think there is a chance that the two contactors will not disconnect simultaneously, so the last contactor to...

Sometimes I feel we are overthinking all this, I don't think that the inverters with the build-in transformers have this much fault monitoring and disconnects build-in. I am not trying to derail your safety circuits, just trying to keep things in perspective. Where do we stop?

See attached example of potential neutral current flow in ground wire if we add a second N/G Bond. In 'Solar Disconnect Service Panel' the Neutral current can go two different ways, #1 through N/G Bond back to Main Service Neutral or, #2 Through Auto Transformer to L2. Sorry to make a mess out...

I think your Diagram "derived_main_panel_v2.png" still puts your AT in parallel with the grid transformer when in On-Grid Mode. Because the AT neutral is connected to the main service panel neutral through the ground wire from Main Service Panel to Derived Main Panel.

What if we had an AT temp monitoring circuit that could disconnect AT input Power? "Lost Neutral fault" would not disconnect AT Input, this would allow it to auto-reset after an ATS transition. AT would be protected by OCP and Over-Temp protection. What components do we need to build the AT...

I like @Coty idea of having a dedicated sub-panel for all 120V loads, see post#10. But I think he will still have objectionable neutral current flowing in the ground wire that bonds 120V panel ground to the Main Utility Panel ground. See attached diagram for my solution to this. I am using...

Will the EG4 Inverter communicate with Solar Assistant? Why do you want battery to inverter communication? Solar Assistant can get more detailed info by communicating both with the Batteries and Inverter, than getting just the info that the Inverter collects from the battery (i.e. Battery Temp...

Great point @ususus, We could drive a separate GEC for the 'derived main panel' and not use the GN-GN bond link between the service and derived main panel as you proposed in Post#22 Option#1, this would solve the objectionable neutral current problem. But that leaves us with no safety ground for...

I would agree that this may not be code correct, but I think it is a safe way of doing it because the 30A breaker for AT will prevent an overload on the AT if, for some strange reason, it is balancing loads for an external customer.

This feature would be great on Off-Grid installations, Back-up generator would only have to be big enough to charge batteries (80A). Instead of powering all loads and charging batteries.

You could simplify things by putting the 240V loads on the "Inverter disconnect Service Panel" instead of having another separate Load center just for 240V.

Here is the reply that I got from Solar Assistant Support.

When you do this remember my "burned up the transfer relay" experience. I am guessing as you scale it up with multiple GW you will end up using a bigger contactor rather than paralleling multiple contactors.

This diagram looks great to me! I was planning on running the Hot wire from breaker thru dry contact instead of the neutral wire like you do, but this will work just as well. Not that it matters, but I always put my switches on the Hot wire, is there any special reason why that you are...

In the current schematics, you guys are not disconnecting the input side of the AT, only disconnecting the loads from the AT.

I have this LifePOWER4 version of the EG4 batteries communicating with Solar Assistant, I connected multiple batteries just like your picture shows. I would guess your dip switch setting is not correct, remember after changing the dip switch, you need to power cycle the battery for the new dip...

AC IN and AC Out Grounds are connected internally. see the attached drawing of Ground Fault Example.

Will you share the new firmware, please? Also, do you have a link to the driver for "Exar Corp (xr21v1410)". Thanks,

Are you running the Cotek 24V 3000W inverter off of the same "one EG4LL 48v battery"? My experience is, that you need a minimum of 2 or 3 of the EG4LL 48v batteries to start a high surge load. The battery BMS has short circuit and overload protection built-in, when it sees that high surge it...

I don't think you need any Neutral wire and 'neutral switching contactor' from Main Service to Solar disconnect panel if you are using a contactor to Switch the N/G bond in 'Solar disconnect panel'. I had originally suggested having a Neural wire between Main Service and Solar disconnect panel...

Thank-You Crowz I will give it a try.

Do this test with them daisy-chained, set all batteries dip switches to 2, then turn on each battery individually, and use Solar Assistant to connect to each individual battery. If this works then you know your daisy-chained communication cables are good.

Connect the Red wire with "?" to your GW dry contact. You are getting really Close!

This contactor may work, a bit better price. CWB50-11-30D15

I believe if the fault to chassis or to the electrical box happens after the breakers in "AC in panel" then these breakers will protect it. But if the fault happens on the wires leading from meter to AC in panel then there is no ground fault protection. I was wrong, see @Hedges post#52 below

If you reduce the upstream OCPD to 30A then you only need one "Lost N Contactor".

The 120V coil on the contactors usually has a pretty wide operating voltage, I am guessing it will not disconnect even if you turn off the 30A breaker feeding the Auto Transformer. watch the video that @Desert_AIP posted. When testing, be sure to only use loads like light bulbs, that you don't...