Utility Interconnection Question

[ncsolarelectric]

Is it permissible to interconnect a grid-tied, utility-interactive inverter that can be programmed for zero (0) Export to the grid, without an interconnection agreement with the utility?

I have been involved in over 300 interconnections to utilities all over the country, including systems that were not allowed to export. All of them required an interconnection agreement because the inverters operate in parallel with the utility grid. I can understand that the AIMS Power inverters, EG4, and MPP inverters are off-grid and are not utility-interactive. They only draw power from the grid. But a Sol-Ark is utility-interactive. I hear it can be programmed not to export but still operate in parallel with the utility grid up to the amount of energy used by the home.

Has anyone interconnected a Sol-Ark inverter and used it this utility-interactive way without a utility interconnection agreement? Successfully?

Thank you.

Best,
Todd

 

[sunshine_eggo]

IMHO, if you don't get caught, sure. If you have a system that monitors and truly achieves net zero export, then your chances improve. There are some low-end GT battery-less inverters on Amazon that also monitor for zero export.

https://www.amazon.com/Inverter-Limiter-DC50-90V-AC185-265V-SUN-2000GTIL2-H/dp/B08F9Y6WKJ

 

[BentleyJ]

IMHO, if you don't get caught, sure. If you have a system that monitors and truly achieves net zero export, then your chances improve. There are some low-end GT battery-less inverters on Amazon that also monitor for zero export.

https://www.amazon.com/Inverter-Limiter-DC50-90V-AC185-265V-SUN-2000GTIL2-H/dp/B08F9Y6WKJ

As stated above, can a grid-interactive inverter truly limit export to zero? For example our Schneider inverter when in Peak Load Shave mode does not limit incoming utility power to absolute 0 even though Amps is set to 0 in the user menu. The batteries service the majority of the load but after a few hours there can be 100 to 500Wh of utility power usage. This is the reverse of 0 export but I believe the principle still may apply. The Digital Meters are fairly sensitive even though they may not be programmed to measure power back to the grid if you are not a NEM customer, there is a good chance they can detect it and "rat you out" with wireless communication.

 

[sunshine_eggo]

I would hope that "zero export" systems would permit configuration to ensure not just zero export, but also "negative export," i.e., it will never back feed to 0, but maybe 200W or something like that.

 

[High Expectations]

Bumping this thread for more thoughts on utility interconnection agreements. My utility will not allow any inverter connections in parallel with a grid feed, due to "short circuit constraints at the transformer station". Exporting/Non-exporting, "limited-to-home" doesn't matter. No parallel connections allowed, they were very clear. Is the only way around this to install an off-grid system with bypass, like the MPP? I was hoping to avoid the cost and complexity of batteries. I can guarantee that I will be consuming all that I produce. I just need the grid to dynamically top up as loads fluctuate or clouds roll by...

 

[Ampster]

Is the only way around this to install an off-grid system with bypass, like the MPP?

It is a gray area. I think the utilities have done an excellent job of defining parallel operation to their advantage. My belief is that we have a fundamental right to generate electricity behind our meters as long as that is done consistent with the building codes in effect in our jurisdiction. Interesting that you mention MPP because if I remember correctly MPP is not UL listed and if that is true, then it would be a violation of my current building code.

 

[OffGridInTheCity]

Earlier in my solar journey I experimented with grid-tie w/limiter - the cheap kind you plug into a 120v socket - but was afraid that power would leak back to the grid so I abandoned that approach and went with a series of UL listed ATSs - e.g. mechanically interlocked relays will not allow backfeed

My offgrid AC / grid AC are hooked to a series of ATSs so that when I have solar power the ATSs switch to offgrid AC and when the solar power runs out (inverters shut down), it auto switches back to grid. Much like an all-in-one (off-grid oriented) MPP Solar except the MPP Solars have UPS built-in. I had to do my own UPS to cover the switching. The worry of motor surge due to mismatched sine-waves at switch-over did not materialize for me - no problems.

 

[John Frum]

My belief is that we have a fundamental right to generate electricity behind our meters as long as that is done consistent with the building codes in effect in our jurisdiction.

Also a responsibility to not back feed.
If the POCO came after you for backfeeding I wonder if you could go after Sol-Ark or similar?
I think you would be caught in the middle between very expensive lawyers.

 

[Ampster]

Also a responsibility to not back feed.

Yes, I should have mentioned that. Although I have a NEM agreement for the GT part of my system. The hybid which I added later is export limited.

If the POCO came after you for backfeeding I wonder if you could go after Sol-Ark or similar?
I think you would be caught in the middle between very expensive lawyers.

I am on a NEM agreement with the GT part of my system and have limited my export to the kiloWatts specified in that agreement. My only risk is that my hybrid is not technically registered or approved by my utility but the likelihood of them catching me is very small. If they did it would be either a revocation of my NEM agreement or worse case the equivalent of a parking ticket. As far as I can tell in California it is not in any of the criminal statutes. That may not be the case in other parts of the country.

 

[OffGridInTheCity]

Yes but.... its the chance that one might shock (injur) a lineman if unauthorized backfeed leaks into the grid that gives me great pause. I'm not critical of DIY decisions, just sharing why I personally decided not to risk it.

 

[Ampster]

Yes but.... its the chance that one might shock (injur) a lineman if unauthorized backfeed leaks into the grid that gives me great pause. I'm not critical of DIY decisions, just sharing why I personally decided not to risk it.

No backfeed is authorized when the grid is down and I suspect it constitutes a case of criminal negligence to operate a device that could do that. The thing that many people do not realize is that if the backfeed gets through a tranformer it could be tranformed to thousands of volts. My hybrid is fully UL listed and has protections to prevent that. I would not be messing with anything that was not safe. Backfeed can have several meanings and I make a distinction between safe export and unsafe backfeed when the grid is down.

 

[agt]

@Ampster for California, there do appear to be criminal penalties (misdemeanor) for connecting a parallel generator without utility approval and permission:

Codes Display Text

I don’t see generator defined anywhere, so it would be up to the jury to decide whether that law applies to an unapproved grid tie inverter.

I personally would be comfortable connecting a ul1741 rated inverter without utility permission, but if said device caused injury/death I could see being charged under HSC 119075, alongside criminal negligence etc.

 

[Ampster]

@Ampster for California, there do appear to be criminal penalties (misdemeanor) for connecting a parallel generator without utility approval and permission:

Yes, that clearly is the statute and as I said earlier the utilities have probably defined generator to include my hybrid inverter. I do not see where I have to ask permission but it requires a double throw switch. I will have to look at my Skybox and see if the transfer relay constitutes a double throw switch. Maybe my interlock qualifies as a "double throw switch"? It is clear it is a misdemeanor and subject to a fine. I will probably be less aggressive about advocating as i have in the past. Thanks for the link. I have printed it out for my reference.
To be clear I also have a NEM agreement and PG&E has used inclusive language to define my generating facility but as mentioned earlier I could very easily be in breach of that agreement. At worse case a breach of contract means they cancel my NEM agreement and then try to force me onto NEM 3.0.

 

[Danke]

Yes but.... its the chance that one might shock (injur) a lineman if unauthorized backfeed leaks into the grid that gives me great pause. I'm not critical of DIY decisions, just sharing why I personally decided not to risk it.

I have a Generac 200A service rated ATS. I would think that covers it.

 

[Danke]

@Ampster for California, there do appear to be criminal penalties (misdemeanor) for connecting a parallel generator without utility approval and permission:

Codes Display Text

I don’t see generator defined anywhere, so it would be up to the jury to decide whether that law applies to an unapproved grid tie inverter.

I personally would be comfortable connecting a ul1741 rated inverter without utility permission, but if said device caused injury/death I could see being charged under HSC 119075, alongside criminal negligence etc.

All I see in that link is “ shall notify the utility of the location of the generator”

I don’t see “utility approval and permission”

 

[agt]

All I see in that link is “ shall notify the utility of the location of the generator”

I don’t see “utility approval and permission”

119075c “Any electrical generator, other than a generator designed to run in parallel with the system of the serving utility and approved by that utility…” must have a transfer switch.

But if that approval applies to the model, and not the specific installation…

 

[Danke]

119075c “Any electrical generator, other than a generator designed to run in parallel with the system of the serving utility and approved by that utility…” must have a transfer switch.

But if that approval applies to the model, and not the specific installation…

(c) Any electrical generator, other than a generator designed to run in parallel with the system of the serving utility and approved by that utility, that is capable of being permanently connected to a customer’s electrical system shall be connected only by means of a double throw switch so as to isolate the customer’s electrical system from that of the electrical corporation or state or local agency.

 

[OffGridInTheCity]

I have a Generac 200A service rated ATS. I would think that covers it.

Yes sir. I couldn't quite swing one of these and it seemed quite complicated / wasn't sure if I could adapt it for a non-generac generator situation - so I went with multiple Progressive (UL listed) ATSs which are 240v @ 50a each.

The (more modest) Progressive ATSs are simple - when they sense power (from my inverters) on the generator leg the relays switch over to that source and when the power goes off, they auto-switch back to grid.

Not sure how to get a Generator 200A ATS to switch... Is it automatic if it senses power on the generator input? and does it auto-switch back to grid when the generator power stops? or do you have to 'direct it' on what to do somehow. I couldn't figure out if a Generac generator is required to get it to work properly.

 

[Shimmy]

Is the only way around this to install an off-grid system with bypass, like the MPP? I was hoping to avoid the cost and complexity of batteries. I can guarantee that I will be consuming all that I produce. I just need the grid to dynamically top up as loads fluctuate or clouds roll by...

You can dc-couple to the utility if you want: utility powers a battery charager -> small battery -> hybrid or off-grid inverter. You don't need much of a battery for this use case, and there is nothing against Rule 21.

I believe, but am not certain, that you can actually set up a Schneider XW-Pro to work this way; you can disable the inverter when you close the AC input. Without that you would want some kind of bypass contactor or circuit breaker pair.

 

[Danke]

Yes sir. I couldn't quite swing one of these and it seemed quite complicated / wasn't sure if I could adapt it for a non-generac generator situation - so I went with multiple Progressive (UL listed) ATSs which are 240v @ 50a each.

The (more modest) Progressive ATSs are simple - when they sense power (from my inverters) on the generator leg the relays switch over to that source and when the power goes off, they auto-switch back to grid.

Not sure how to get a Generator 200A ATS to switch... Is it automatic if it senses power on the generator input? and does it auto-switch back to grid when the generator power stops? or do you have to 'direct it' on what to do somehow. I couldn't figure out if a Generac generator is required to get it to work properly.

No, it doesn‘t have to be a Generac generator. If the ATS senses power drop from grid for X amount of seconds, it will fire up generator. Also, some inverters can control the generator, like the Sol-Ark I am installing. There are settings when you wish to have generator start and stop. Like at certain SOC of batteries. My plan would be to run off of batteries until ~20% SOC, then have generator start for home power and charge batteries until ~80 SOC. I can always change this setting on the fly, even remotely. So if I know my panels will be producing power in a few hours, I will either turn off the generator manually, or set the SOC % lower to shut off generator.