Minor Backfeed Issue with Utility

[zanydroid]

Op should stand on the fact his system cannot feed the grid and is not in parallel and then make them prove they are seeing back feed

This presumes that the LVPs are actually implemented correctly / correct configuration is set. With that tier of equipment I wouldn’t be surprised if it is equally or less flaky than the POCO meter and IT.

If air gapping eliminates the backfeed detection then it was likely parallel despite whatever is in manual or believed to have been the config.

 

[Hedges]

If it was unintentionally backfeeding, consider a small GT PV system with PTO, unless costs or change in terms are prohibitive. That would cover for spurious backfeeds by guerilla system.

 

[1201]

This presumes that the LVPs are actually implemented correctly / correct configuration is set. With that tier of equipment I wouldn’t be surprised if it is equally or less flaky than the POCO meter and IT.

If air gapping eliminates the backfeed detection then it was likely parallel despite whatever is in manual or believed to have been the config.

Maybe @Hedges can confirm but I don't think an offgrid inverter can backfeed the grid. If it's not designed to/cannot synchronize the sine wave, how would backfeed happen? Seems more likely that something would blow in dramatic fashion

 

[zanydroid]

If it was unintentionally backfeeding, consider a small GT PV system with PTO, unless costs or change in terms are prohibitive. That would cover for spurious backfeeds by guerilla system.

This will not paper over spurious backfeed during dark hours , which is possible with the battery but not the GT with no battery

 

[zanydroid]

Maybe @Hedges can confirm but I don't think an offgrid inverter can backfeed the grid. If it's not designed to/cannot synchronize the sine wave, how would backfeed happen? Seems more likely that something would blow in dramatic fashion

Some of these off grid units are marketed as hybrid overseas. Granted they should have checked when they converted hardware to 120/240.

You want to sync to minimize SBU transfer time. This is however only a nice to have, not a must

 

[1201]

Some of these off grid units are marketed as hybrid overseas. Granted they should have checked when they converted hardware to 120/240.

You want to sync to minimize SBU transfer time. This is however only a nice to have, not a must

I'm willing to bet there is no syncing of any kind with these inverters

 

[zanydroid]

I'm willing to bet there is no syncing of any kind with these inverters

Could be.

But note that this granularity of monitoring is new in the U.S., they could have gotten away with dropping in hybrid equipment for years without people noticing. It’s not like syncing+zero export is rocket science or expensive either. See how cheap GTILs are

 

[fmeili1]

I'm willing to bet there is no syncing of any kind with these inverters

They do!
Assuming, the AIO is running in inverter mode (e.g. SBU) without AC-in connected (AC-in breakers OFF). As soon as the AC-in gets connected to the grid (while AIO is still in SBU mode), the inverter syncs relatively fast with the AC-in (grid) to be prepared to use the grid if required (depending on various settings).
As @zanydroid mentioned, some of these AIO's (Voltronic clones like MPP LV6548, EG4-6500, etc.) are re-branded as hybrid in other markets! Good example is the Phocos Any-Grid 6.5k AIO which is nearly the same as the EG4-6500EX. If you're looking in the manual of this Phocos, there is a setting 08 "Solar power feed-in into grid" which requires a PIN from the vendor to enable it and with the hint "Grid feed-in / injection may not be legal at the site of installation". In the EG4-6500EX the program 08 does not exists. I'm pretty sure it's just a re-branded firmware thing if a vendor decides to use this (always existing) feature or not. Without this feature it's maybe easier to get a local certificate if using as on off-grid only system.

 

[zanydroid]

They do!
Assuming, the AIO is running in inverter mode (e.g. SBU) without AC-in connected (AC-in breakers OFF). As soon as the AC-in gets connected to the grid (while AIO is still in SBU mode), the inverter syncs relatively fast with the AC-in (grid) to be prepared to use the grid if required (depending on various settings).

I looked at the spec sheet for this inverter and they claimed 15/20ms transfer. Which strongly suggests syncing.

 

[1201]

They do!
Assuming, the AIO is running in inverter mode (e.g. SBU) without AC-in connected (AC-in breakers OFF). As soon as the AC-in gets connected to the grid (while AIO is still in SBU mode), the inverter syncs relatively fast with the AC-in (grid) to be prepared to use the grid if required (depending on various settings).
As @zanydroid mentioned, some of these AIO's (Voltronic clones like MPP LV6548, EG4-6500, etc.) are re-branded as hybrid in other markets! Good example is the Phocos Any-Grid 6.5k AIO which is nearly the same as the EG4-6500EX. If you're looking in the manual of this Phocos, there is a setting 08 "Solar power feed-in into grid" which requires a PIN from the vendor to enable it and with the hint "Grid feed-in / injection may not be legal at the site of installation".

I don't have one of these inverters but SBU switches to grid if solar and battery are not enough correct? That's a switch not a sync. I could be wrong

 

[1201]

I looked at the spec sheet for this inverter and they claimed 15/20ms transfer. Which strongly suggests syncing.

With syncing there is no transfer

 

[niktak11]

My utility saw probably less than 10 watts on just one day for a few minutes and called me on it. So yes, the smart meters can see small amounts. Whether the utility will say or do anything depends on their policies.

Mine did the same but I had my system running for about 18 months before they finally drove out to my property. It probably took them so long because they thought it was a faulty meter and not a solar system.

 

[zanydroid]

With syncing there is no transfer

For proper hybrid it is better to sync before transferring or paralleling.

For instance if you are running off grid and power comes back. You sync first, and then close grid connection.

Same with going from U to B. You want to sync inverter first (when isolated from grid) then throw the relay.

In both cases your appliances will be thankful

 

[fmeili1]

I don't have one of these inverters but SBU switches to grid if solar and battery are not enough correct? That's a switch not a sync. I could be wrong

@AntronX posted a schema which explains it a bit. The output of the inverter part of the AIO is connected with the AC-in (via a relay). So it seems that it's just a thing of how good and fast the current and voltage sensing and control unit preventing backfeeding (in officially off-grid only AIO's).

 

[1201]

For proper hybrid it is better to sync before transferring or paralleling.

For instance if you are running off grid and power comes back. You sync first, and then close grid connection.

Same with going from U to B. You want to sync inverter first (when isolated from grid) then throw the relay.

In both cases your appliances will be thankful

True hybrid doesn't transfer, it syncs then connects the grid into the path. Off grid inverter is going to be either grid sine wave or inverter sine wave

 

[niktak11]

With that usage you're probably gonna want 2 18kPVs or similar if you're fully offgrid

 

[zanydroid]

True hybrid doesn't transfer, it syncs then connects the grid into the path. Off grid inverter is going to be either grid sine wave or inverter sine wave

If I bought an AIO I would much prefer it sync before transferring, and pay more for it. I have gamed it out several times in my thought experiments.

 

[fmeili1]

I don't have one of these inverters but SBU switches to grid if solar and battery are not enough correct? That's a switch not a sync. I could be wrong

Yes, but as soon as the AC-in IS connected to the grid (even if not used because still running in SBU mode), the syncing starts. You can "see" this if you switch on the AC-in breakers while the unit is still in SBU mode you notice a slight flickering with lights - I'm sure this is the moment when the internal "off-grid-inverter" syncs with the grid to be prepared for a later "clean" transfer into bypass mode if required.

 

[zanydroid]

I think another way to think about this is. Suppose running in SBU mode, and one of the loads surges past inverter capacity. The inverter will have to flip to bypass mode. Ideally you want it synced so the only disruption is the time to flip the contactor. And if it was a zero crossing SSR the appliances may not even notice.

 

[AntronX]

Sounds like you need minimum load on your meter for it to always read consumption. If they are bitching about 1w "ripple" then hookup 10w incandescent light bulb before the inverter and see if they go away. Or like others suggested set up minimum grid load in your inverter. Sounds like Duke Power is the worst. I backfed my FPL meter for a while and they never complained.