Zero export system without interconnection agreement

[wwhitney]

That's a specific clause not the intent which is "The Legislature intends to prevent electricity generated by permanent or portable electric generators from backfeeding into a utility electrical distribution system ..."

Not sure we need to argue about the intent, when it is clear that a parallel-operated, non-export system without an interconnection agreement violates the section and is illegal.

Cheers, Wayne

 

[jaggedben]

Thanks for the link but I was looking for something more specific to zero export systems. In any case, the law's explicit intent is to avoid backfeeding so zero export systems would comply with the intent.

Zero export (as it is commonly implemented at present) isn't the same as no backfeed. It typically involves backfeeding on one leg/phase and importing on the other since the load is almost never balanced.

Good question. Based on some quick searches, there are over 11 million RV's in the US (https://www.rvia.org/media-resources) and more than 1 million people live in RV's full time (https://www.washingtonpost.com/business/2018/11/12/million-americans-live-rvs-meet-modern-nomads/) who are more likely to have inverters. The numbers are much higher than I had expected. Also, it seems inverters started becoming standard on at least some RV's in the early 1990's (https://www.irv2.com/forums/f44/when-did-rv-start-using-inverters-and-battery-banks-497651.html). So, I would not be surprised if the number of RV inverters in use would be in the tens if not hundreds of thousands.


So an RV owner would have to have an interconnection agreement with the POCO for each RV park that he uses? Doesn't seem practical.

I see your point.

Well, if you look the law you referenced it's not so clear. I think an inverter would be classified by most as primarily an "electric generator" and its charging function is just a secondary function. The law doesn't provide explicit exemption for electric generators used in charging mode. To make it even more unclear, many inverters literally use the same circuit components to generate or consume electricity via dynamic control that can change the mode frequently. It seems the law was written with primarily gas generators in mind so the specific clauses don't work well for modern inverters especially when it comes to zero export systems. If you follow the intent of the law then it seems clear that zero export systems are exempt as they do not cause materially significant backfeeding. However, if you follow the literal clauses then it seems zero export systems would not be exempt. I think more clear laws are needed.

See what Wayne said. The law is pretty clear. It states an intent, a means to enforce that intent, and an exception that requires approval from the utility.

Clearer laws are needed if you want to legalize zero-export systems without interconnections, yes. But that would be overreach. We just need laws or regulations that provide for a near-zero interconnection application cost and no bill penalty.

I am mainly playing Devil's advocate so I can have better responses ready for people challenging interconnection agreements

Fair enough.

 

[winnie]

Intent matters because the different stakeholders in the issue have different priorities.

The utility is operating under a tariff scheme that charges residential customers for energy used.

PV can have the effect of reducing energy used without reducing peak demand; thus the utility is saddled with infrastructure costs and availability costs which are borne by fewer kWh. So the utility will have an incentive against PV. (There are also utility incentives for PV, and it is a complex mess, not going to explore the full issue here.)

The law's intent is to protect lineworkers. The law specifically permits local generation with an interlock, without requiring an interconnect agreement. So if I have a generator or PV system that doesn't operate in parallel with the utility, I am kosher under the law.

The 'zero export' systems are a different beast; they _cannot_ endanger lineworkers, and they are supposedly designed to prevent any sort of kWh flow in the direction of the grid. But they are parallel operation prohibited by the law.

If we read the stated intent of the law, there is a good argument to be made that the law should be changed to allow properly rated zero export systems. On the other hand the utility might fight these changes even though these systems don't endanger lineworkers. The utility might even try to argue against reliably 'air-gapped' PV systems which absolutely cannot export or generate to the line (such as the DC coupled systems or the PV supported minisplits that I described toward the beginning of the thread).

-Jon

 

[tortuga]

I learned that many RV/boat inverters (e.g. Victron, etc.) have had a "Power Assist" (https://community.victronenergy.com/questions/29128/power-assist.html) feature for quite a while. Basically, the feature allows the inverters to sync up to shore power (much like grid-tied inverters) and produce additional power from batteries to help power loads requiring more power than what the shore power can provide. So, the feature effectively works like an interconnected zero export system.

That is really interesting, while I have no interest debating the legality of it,
I am really interested in why do it that way?
and not like a UPS as I described in post 144?
A VFD converts AC to DC then back to AC, so so does a UPS, and you get some advantages from doing it that way.
Why in the world do they design it like this anyway?
From that PDF link in the other forum:

 

[wwhitney]

The 'zero export' systems are a different beast; they _cannot_ endanger lineworkers

True if operating as intended, but I don't think it's that simple. You need to consider the failure modes, and consider how those failure modes compare with the failure modes of the methods that are allowed under the law. I can imagine reaching the conclusion that the likelihood of energizing the distribution network is unacceptably higher with 'zero export' schemes.

Cheers, Wayne

 

[GeorgeB]

That is really interesting, while I have no interest debating the legality of it, I am really interested in why do it that way?

2 thoughts, not facts;

1, with limited source (15A circuit or small generator, 10A common rating), it allows using a load requiring more than the line/generator can operate; the washing machine motor, hot plate, microwave, etc, can be supplemented via battery inverter. Call that integrating the need over time.

2, I really appreciate why utilities insist on grounding any lines on which they work.

 

[tortuga]

2 thoughts, not facts;

1, with limited source (15A circuit or small generator, 10A common rating), it allows using a load requiring more than the line/generator can operate; the washing machine motor, hot plate, microwave, etc, can be supplemented via battery inverter. Call that integrating the need over time.

I guess I am thinking that I would size the inverter to run the entire load of the boat or RV and have a lithium ion battery bank as the backup, and a AC/DC converter
Especially with a boat, then say you sailed around to somewhere that only had 50/hz shore power, your just converting that to DC and have all your normal 60/hz stuff on the boat.

 

[analog8484]

Not sure we need to argue about the intent, when it is clear that a parallel-operated, non-export system without an interconnection agreement violates the section and is illegal.

Cheers, Wayne

Intent of laws is a key factor in interpretation and enforcement of laws and potential changes to laws. The "letter vs spirit" of law discussion has a long history and is ongoing. Here a paper (https://lsa.umich.edu/content/dam/o.../oshonorsthesis/Matt Gordon_Honors Thesis.pdf) that explains why some laws (e.g. jaywalking) are little enforced when the letter of law is violated but not the spirit (i.e. intent) of the law.
.

 

[analog8484]

That is really interesting, while I have no interest debating the legality of it,
I am really interested in why do it that way?
and not like a UPS as I described in post 144?
A VFD converts AC to DC then back to AC, so so does a UPS, and you get some advantages from doing it that way.
Why in the world do they design it like this anyway?
From that PDF link in the other forum:
View attachment 2559542

The reason for the feature is because you may stop at a random RV park where the shore power outlet can't power everything you need in your RV.

 

[wwhitney]

Intent of laws is a key factor in interpretation and enforcement of laws and potential changes to laws.

OK, then we can disagree on the intent. You can look at the section and say (perhaps as a devil's advocate) "well, the intent is satisfied with just some method of avoiding backfeeding, we don't need to regulate how good or reliable a method that is." And I can look at the section and say "well, a specific method of avoiding backfeeding is specified, so the intent is to provide at least that level of protection, and if we want to allow alternate methods, we had best show they are at least as good and reliable."

Cheers, Wayne

 

[analog8484]

"well, the intent is satisfied with just some method of avoiding backfeeding, we don't need to regulate how good or reliable a method that is."

Why couldn't some kind of UL standard (like rapid shutdown) be developed/used to ensure reliability of anti-backfeeding/zero-export mechanism?

It seems the laws could be updated in a straight forward manner to better reflect the original intent without real safety compromises.

 

[wwhitney]

Why couldn't some kind of UL standard (like rapid shutdown) be developed/used to ensure reliability of anti-backfeeding/zero-export mechanism?

It seems the laws could be updated in a straight forward manner to better reflect the original intent without real safety compromises.

Sure, that seems like a reasonable idea and I'd be happy to see that happen.

But until that happens, the systems are illegal to install without an interconnection agreement.

Cheers, Wayne

 

[jaggedben]

...

The 'zero export' systems are a different beast; they _cannot_ endanger lineworkers, and they are supposedly designed to prevent any sort of kWh flow in the direction of the grid. But they are parallel operation prohibited by the law.

They are not prohibited if they are designed for it an approved by the utility. It's the latter bit that some want to question.

If we read the stated intent of the law, there is a good argument to be made that the law should be changed to allow properly rated zero export systems.

I don't think this law would need changing if other laws, regulations or tariffs were considered.

By the way, maybe this was mentioned way up thread, but for PG&E at least, there is a non-export interconnection option. It's just very unfair when compared to the net metering option. ($800 fee vs $145 for residential, and some unreasonable insurance requirements.) If those requirements were changed things would be more fair. And we probably wouldn't need to have this discussion.

The utility might even try to argue against reliably 'air-gapped' PV systems which absolutely cannot export or generate to the line (such as the DC coupled systems or the PV supported minisplits that I described toward the beginning of the thread).

I think they would have a very hard time fighting that, other than through fair economic competition. It'd be like prohibiting clothes lines.

 

[ggunn]

By the way, maybe this was mentioned way up thread, but for PG&E at least, there is a non-export interconnection option. It's just very unfair when compared to the net metering option. ($800 fee vs $145 for residential, and some unreasonable insurance requirements.) If those requirements were changed things would be more fair. And we probably wouldn't need to have this discussion.

Like most issues, what is considered "fair" depends on who you ask. "Advantageous" is probably a better word if one is looking for objectivity..

 

[wwhitney]

"fair"

I can't see any argument that would support a utility charging you more when you say "I have this parallel operated system I'd like to use, but it will never export" compared to when you say "I have this parallel operated system, please let me export energy to you, and let the meter run backwards." [Although at a rate a few cents lower than the consumption rate, due to the Non-Bypassable Charges.] The latter is obviously a bigger ask, so why is the one time fee bigger for the former? That makes no sense.

Cheers, Wayne

 

[ggunn]

I can't see any argument that would support a utility charging you more when you say "I have this parallel operated system I'd like to use, but it will never export" compared to when you say "I have this parallel operated system, please let me export energy to you, and let the meter run backwards." [Although at a rate a few cents lower than the consumption rate, due to the Non-Bypassable Charges.] The latter is obviously a bigger ask, so why is the one time fee bigger for the former? That makes no sense.

Cheers, Wayne

Ask the utility; I'll wager that you will get a different take on it. Utilities tend to consider another source connected to their grid as contributing to it and therefore under their jurisdiction irrespective of the magnitude and direction of power flow through their meter; if you connect a PV system to the grid without an interconnection agreement they can and likely will terminate your service. I'm not saying that it's right or wrong, only that that is the way it is.

 

[jaggedben]

Like most issues, what is considered "fair" depends on who you ask. "Advantageous" is probably a better word if one is looking for objectivity..

Objectively there's not much reason why an interconnection application process should be much different for a non-export vs a net metered system that otherwise uses the same equipment.

That's independent of the question of how much is fair to charge in fees or what tariff the customer gets billed on.

 

[wwhitney]

if you connect a PV system to the grid without an interconnection agreement

That was completely not the point of my last comment. My point was, when you are getting an interconnection agreement, why should the utility charge more for a non-export agreement than for a NEM agreement? The former is clearly a better deal for them, so why charge more? That's what PG&E does, per jaggedben.

Cheers, Wayne

 

[ggunn]

That was completely not the point of my last comment. My point was, when you are getting an interconnection agreement, why should the utility charge more for a non-export agreement than for a NEM agreement? The former is clearly a better deal for them, so why charge more? That's what PG&E does, per jaggedben.

Cheers, Wayne

Then I won't comment since I don't have any firsthand knowledge of such a thing. Sorry if I misinterpreted what you said.

 

[tortuga]

The reason for the feature is because you may stop at a random RV park where the shore power outlet can't power everything you need in your RV.

With a AC -> DC -> AC setup like A VFD would achieve the same thing.
You just size the DC converter and inverter to power the entire RV