[RE-wrenches] Truly Zero Export

[Jason Szumlanski]

Thanks, Sue. Your response is greatly appreciated.

Can I ask how the Midnite AIO accomplishes this in Off-Grid mode? Does the
inverter turn off grid-passthrough to the loads altogether and just offer
grid voltage to the charger while inverting power from the batteries and
solar to cover the loads? How does the inverter definitively "catch" excess
solar production when a large load is dropped?

I believe what you are saying is true, but I am interested in the mechanics
behind this. I would like to share it with our local electric co-op's chief
engineer. They are raising red flags with the local AHJ for homes that
install solar panels that don't net meter, even if there is no intention of
net metering.


Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208


On Wed, Jun 25, 2025 at 11:48 AM Sue Stankevitz <Sue at midnitesolar.com>
wrote:

> For the MidNite MN15-12K-AIO it has 2 modes that pertain to this discussion
>
>
>
> Off Grid mode will never export out the input terminals at all no matter
> what
>
> Self Consumption will export out the input terminals to the Main Panel to
> try and zero the CT’s out. We have a setting you can adjust that will
> always draw this amount first from the grid to give the inverter some room
> to catch the over shoots when loads turn off. We find around 200 Watts is
> generally a good spot.
>
>
>
> For the MidNite MNROSIE7048RE it has 2 modes as well
>
> Grid Support- This allows Rosie to try and zero the incoming power from
> the grid any time the battery is above a set point you select. Rosie will
> always draw the first 150-200 watts from the grid to allow it to catch the
> over shoots when a load goes away
>
> VDC Connect / Disconnect- This mode allows Rosie to open its relay any
> time the battery is above a value you select eliminating ANY possibility of
> over shoot when loads go away.
>
>
>
> If you are working with a municipality where there is absolutely zero room
> for error it is best practice to use the more conservative approach of Off
> Grid Mode or VDC Connect/Disconnect to insure there will never be a chance
> of export however slim or minior.
>
> Sue Stankevitz
> MidNite Solar, Inc. <https://www.midnitesolar.com/index.php>
> (360) 403-7207 (XT122)
>
>
>
> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> *On
> Behalf Of *Jason Szumlanski via RE-wrenches
> *Sent:* Wednesday, June 25, 2025 2:59 AM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Cc:* Jason Szumlanski <jason at floridasolardesigngroup.com>
> *Subject:* [RE-wrenches] Truly Zero Export
>
>
>
> 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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