[RE-wrenches] Truly Zero Export

[Jason Szumlanski]

We've had issues with Enphase systems "leaking" electricity back to the
utility grid despite being in a no export grid profile. A local utility
company gets all bent out of shape if there is even a watt-hour of reverse
meter feed in detected. I understand why it isn't feasible to completely
prevent this with Enphase's system architecture, even with a sizeable
battery.

Off-grid inverters that can't interact with the grid will obviously provide
no export.

My question is about hybrid inverters that are capable of grid sell, but
programmed not to sell. Are they capable of truly Zero Export?

The AIOs with grid pass-through don't seem likely to prevent reverse
current flow, but I could be wrong. I'm not sure I would trust Sol-Ark to
stop grid sell completely. Midnite AIO isn't well enough documented to
understand how off grid mode works. The EG4 18Kpv has some cryptic settings
that seem to imply it has truly a off grid mode, but I'm not sure how that
works, either.

If not AIOs, what about other system architectures? I find it hard to
believe that a Powerwall 3 could operate in a non-grid-interactive manner.
After all, it doesn't even support fully off-grid operation. An EG4
FlexBoss/GridBoss setup would naturally rely on current transformers to
prevent grid export, which is a deal breaker I would think in any method to
prevent grid selling. Other AC Coupled solutions like Franklin seemingly
have no chance of preventing export entirely.

It seems the only way for true no export to work is to invert battery power
at all times, meaning no grid pass-through and no AC Coupling. The
inverter/charger need to operate simply as a load from the grid
perspective. Can any grid interactive inverter system programmatically
change its mode entirely to prevent grid selling?


Jason Szumlanski
Florida Solar Design Group
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