Zero export system without interconnection agreement

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winnie said:
IMHO the reason that 'virtual' zero export _might_ be different than 'assured' zero export is that with 'virtual' you might see some really funky power factor issues. You might see power exported during part of the AC cycle and consumed during the rest of the AC cycle, netting out to no export. A home with such a system might consume very few watts but lots of volt amperes.

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-Jon
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Are those technical terms? "Virtual" and "assured" I mean? What would be the difference? I understand (conceptually) how interconnected systems can create interesting power factor situations. I don't understand, fundamentally, why there should be a difference between different kinds of systems.
 
gadfly56 said:
If the zero-export system isn't air-gaped with respect to the grid, I don't see how you get around an interconnection agreement.
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ggunn said:
That's not the way it works in most places. If you are going to interconnect with the electrical grid, in most jurisdictions the AHJ will have some control over what you do with anything that touches their wires no matter if you never export a single kWh.
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I admit I haven't dug into it, but I will conjecture this "grid tie with zero backfeed" thing is a gray area most places.

I will happily accept any specific language you can find on the subject.
 
electrofelon said:
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I admit I haven't dug into it, but I will conjecture this "grid tie with zero backfeed" thing is a gray area most places.

I will happily accept any specific language you can find on the subject.
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Here's some language from PG&Es Rule 2:

6. Any non-PG&E-owned emergency standby or other generation equipment that
can be operated to supply power to facilities that are also designed to be
supplied from PG&E's system shall be controlled with suitable protective devices
by the applicant to prevent parallel operation with PG&E's system in a fail-safe
manner, such as the use of a double-throw switch to disconnect all conductors,
except where there is a written agreement or service contract with PG&E
permitting such parallel operation.
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(Emphasis mine.)

Probably lawyers could get involved but the customer will not have a good case.

Whether you can get away with it without anybody knowing is a different question than whether it's allowed.
 
jaggedben said:
Are those technical terms? "Virtual" and "assured" I mean? What would be the difference? I understand (conceptually) how interconnected systems can create interesting power factor situations. I don't understand, fundamentally, why there should be a difference between different kinds of systems.
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I made up the terms for use in this thread to describe two different scenarios.

'Virtual' zero export: the inverter is an energy source which operates in parallel with the grid, fully capable of energy export to the grid but prevented from doing so through the use of metering.

'Assured' zero export: the inverter is not in parallel with the grid and energy flow is only possible in one direction.

An example of an assured system is an 'off grid' design where the inverter directly powers all the loads of the home, and utility power is used through a one way rectifier or battery charger to add power as necessary into the home system.

If the software and inverter control is good, then it may come down to a legal difference only: is the inverter paralleled with the grid?

The example you posted requires an interconnection agreement for parallel operation. So a better naming might be utility parallel or grid tie inverter with zero export control vs an off grid inverter with unidirectional utility makeup power.

Jon
 
analog8484 said:
This https://ramuk.intertekconnect.com/W...3d1b9bca75c9b9a8862586fc000b0adb?OpenDocument shows the inverter has UL1741 compliance.
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This kind of plug & play system has been available from small companies for years, they put a plug on a microinverter and tell people to plug it into an outlet. Most of these companies never reach the point of selling products, if they do manage to offer a product in the USA they are quickly shut down. The UL 1741 listing only covers how the inverter has to operate, it does not test or approve the physical interconnection options with a utility. Just because a product has a UL listing does not mean it's listed to be used in the way someone is trying to use it.
 
analog8484 said:
That's what I thought too but the push back is show me the laws that are broken. And what would be the penalty for zero export PV systems without interconnection agreement? I had assumed there would be some legal means for POCO's to force disconnection but haven't seen one yet. I doubt POCO's would/can disconnect electric service.
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Here's an idea, install a system without telling the POCO, tell them, and see what happens. Please report back how it goes. :)
 
FYI, since these plug & play systems tend to be shown on patios and plugged into GFI-protected outlets that are required outside it also brings up the problem that GFI outlets are not listed for back feed. The GFI electronics may be damaged if they operate while the plug is energized by an outside source. The damage may not result in the plug being dead so it can still be used but without GFI protection. Not good, many ways you can die from these hacked products.
 
gadfly56 said:
If the zero-export system isn't air-gaped with respect to the grid, I don't see how you get around an interconnection agreement.
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I tend to agree but ... they openly claim no interconnection agreement is required ... so I wonder if I (and many others) have missed something ...


1643058627156.png
 
I looked on their web site and couldn't find a spec sheet for the "Safety Gate Adapter," so I don't know exactly what it's doing. But their system obviously relies on their power meter to avoid exporting, so it's just a "virtual no export" rather than an "air gapped no export." And in practice, I would think that a system like that can't avoid occasional instantaneous export, between the time the system sees a change in load/generation and the time the system reacts to that change.

Cheers, Wayne
 
Yeah, they are basically full of it. But as I said above, what you can get away with...

My biggest problem with that little graphic is the plugging into an outlet. That violates code and defeats the overcurrent protection. I really hope that it's either just marketing or that it's not in fact listed, rather than that UL1741 allows such a device to be listed
 
gadfly56 said:
It sounds like you'd be spending a pretty penny to make an obscure point. But hey, as long as it's not my money, go for it.
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What he described should work for VFD driven motors or anything that has a front end rectifier. Parallels power sources to the DC bus but neither source backfeeds to the other source.
 
pv_n00b said:
FYI, since these plug & play systems tend to be shown on patios and plugged into GFI-protected outlets that are required outside it also brings up the problem that GFI outlets are not listed for back feed. The GFI electronics may be damaged if they operate while the plug is energized by an outside source. The damage may not result in the plug being dead so it can still be used but without GFI protection. Not good, many ways you can die from these hacked products.
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Normal anti-islanding protection in the grid interactive inverter should prevent the inverter from backfeeding the GFCI when the grid is down.
What happens in the fractions of a second when the GFCI is opening may or may not be capable of damaging the GFCI electronics.
 
jaggedben said:
Here's some language from PG&Es Rule 2:



(Emphasis mine.)

Probably lawyers could get involved but the customer will not have a good case.

Whether you can get away with it without anybody knowing is a different question than whether it's allowed.
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So of course, this is for PG&E......I am still hanging on to my speculation that it is usually not that specific. I'll look thru my utility's spec book when I get a minute and see what their language is like. Also it would be an interesting legal pursuit (for someone with nothing better to do with excess money) to challenge this prohibition in court.🤨
 
So of course, this is for PG&E......I am still hanging on to my speculation that it is usually not that specific. I'll look thru my utility's spec book when I get a minute and see what their language is like. Also it would be an interesting legal pursuit (for someone with nothing better to do with excess money) to challenge this prohibition in court.🤨
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I'm curious as to what you see as a basis for the suit. I think wwhitney has covered why the POCO might be very concerned regarding the actual impact the connection would have on their distribution system regardless of how fast the inverter or whatever would clamp down on any potential export. I would think that the onus would be entirely on the supplier to prove there would be no deleterious effects.
 
gadfly56 said:
I'm curious as to what you see as a basis for the suit. I think wwhitney has covered why the POCO might be very concerned regarding the actual impact the connection would have on their distribution system regardless of how fast the inverter or whatever would clamp down on any potential export. I would think that the onus would be entirely on the supplier to prove there would be no deleterious effects.
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I see it the opposite, that the POCO would need to show there IS a deleterious effect 😉
 
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