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

[Jason Szumlanski]

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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