[RE-wrenches] 400A (320A) service backup

[Chris Sparadeo]

I only have experience with paralleling multiple Sol-Ark inverters in
larger service size applications, but 320A all the way up to 800A has
worked well for me. The key is to make sure that all AC downstream loads
are accumulated, and separately, DC battery bussing is combined. Whole-site
CTs are crucial as well. AccuEnergy makes Sol-Ark compatible CTs that go
all the way up to 1200A I believe. Trying to run distinctly separate
systems on a single, large service has caused problems. I’m not aware of
any MID “Gateway” type solution that has overcome the 320A conundrum.

On Wed, Feb 4, 2026 at 6:42 PM Blake Gleason via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I assume it works only because the inverters are sync'd in a
> leader/follower(s) coordinated relationship.
>
> But I've certainly had problems getting the full (additive) power out of
> multiple Sol-Arks (for example).
>
> Blake
>
> On Wed, Feb 4, 2026 at 3:31 PM Jason Szumlanski via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Hi all,
>>
>> When backing up a 400A service with multiple paralleled all-in-one
>> inverters by combining the AC inputs and outputs, the individual inverter
>> transfer switches must operate in a synchronized manner. Come to think of
>> it, the same thing applies to backing up 200A service with paralleled
>> inverters. Are these tested for this function? – I assume so.
>>
>> I'm really asking because Sol-Ark seems to be the only brand that
>> specifically addresses 400A service in documentation, although not very
>> clearly in the manual itself. Their training and literature support passing
>> through additive grid pass-through with multiple inverters, which implies
>> that they are additive in their ability to transfer power. See attached
>> examples.
>>
>> I have not found anything from EG4 (for the 18kPV) or the Midnite AIO
>> that specifically addresses this.
>>
>> In other words, how can we assume that paralleled inverters will be
>> additive in terms of their ability to transfer high levels of current that
>> exceed the rating of a single unit? Is that even addressed in listings? The
>> documentation is quite poor from all manufacturers (no surprise there!)
>>
>> I do have a couple of grid-interactive Midnite AIO systems with four
>> paralleled AIOs backing up 400A services, and so far, so good. My engineer
>> signed off on that.
>>
>>
>> Jason Szumlanski
>>
>>
>> * <http://www.floridasolardesigngroup.com/>*
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>
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