In a self-consumption style situation an inverter sells to drop the usage to close to 0 watts. It’s a controlled sell as not to export. The inverter “buys” power from the grid at a low rate to power the first 200w or so of the load. This is designed to prevent accidental selling during large load fluctuations but is not an absolute guarantee against very small very short duration sells.
In Off Grid mode it does not sell it just makes power on the AC Out side. Similar to what you may be familiar with in the old Outback or Magnum inverters. If the AC in is present it passes through and runs the loads if its not present the inverter powers the loads. To complement this for a self use style system you run the grid into the Generator in not AC in and program the generator to start and stop at your desired levels and then the AIO will ignore the grid when the battery is above your programmed set points similar to the Rosie in VDC disconnect/connect Sue Stankevitz MidNite Solar, Inc.<https://www.midnitesolar.com/index.php> (360) 403-7207 (XT122) [cid:[email protected]] From: Jason Szumlanski <[email protected]> Sent: Wednesday, June 25, 2025 12:12 PM To: Sue Stankevitz <[email protected]> Cc: RE-wrenches <[email protected]> Subject: Re: [RE-wrenches] Truly Zero Export 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 <[email protected]<mailto:[email protected]>> 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) [cid:[email protected]] From: RE-wrenches <[email protected]<mailto:[email protected]>> On Behalf Of Jason Szumlanski via RE-wrenches Sent: Wednesday, June 25, 2025 2:59 AM To: RE-wrenches <[email protected]<mailto:[email protected]>> Cc: Jason Szumlanski <[email protected]<mailto:[email protected]>> 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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