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Question About Preventing Grid Backfeed

cs1234 said:
I wish there was a way we could actually affect change and get tiny amounts of spurious feedback legalized without a permitting process, so long as the device meets the basic UL1741(sabcdedf) regs. I'm pretty sure if brought to a vote, it would win if people knew what we were even talking about.
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But it is legal. It's been legal for years, since there are industrial users that have backup generators running synchronized to grid in active standby mode, ready to rip at a moment's notice, since before solar inverters existed. It's called zero export with unintended export, and there are bounds specified by POCOs that allow it.

It's just that people in these forums don't spend enough time reading the governing regulations of their POCO.

Also, people just YOLO on their equipment instead of doing an interconnection agreement of the right classification. Or are using equipment that would not be allowed to interconnect because they don't have the right listing / code approvals.
 
zanydroid said:
But it is legal. It's been legal for years, since there are industrial users that have backup generators running synchronized to grid in standby mode since before solar inverters existed. It's called zero export with unintended export, and there are bounds specified by POCOs that allow it.

It's just that people in these forums don't spend enough time reading the governing regulations of their POCO.

Also, people just YOLO on their equipment instead of doing the interconnection agreement.
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You're telling me, that as a residential user, I don't need a feedback agreement with the Utility provider under a zero export with unintended export clause? And I don't need any type of agreement / permit from an Utility / AHJ ?

I'm pushing for something sold in the store, you plug it in, like a GTIL (except actually made to a decent standard, not the complete death traps sold on Amazon), and you're good to go. Nothing more complicated than that.

Keep in mind, I don't think the Utilities deserve the same rights as actual private companies that don't receive tons of subsidies and monopoly status.
 
cs1234 said:
You're telling me, that as a residential user, I don't need a feedback agreement with the Utility provider under a zero export with unintended export clause? And I don't need any type of agreement / permit from an Utility / AHJ ?

I'm pushing for something sold in the store, you plug it in, like a GTIL (except actually made to a decent standard, not the complete death traps sold on Amazon), and you're good to go. Nothing more complicated than that.
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No.

With my POCO (PG&E) there are two paths:
  • Old school: you have to fill out some forms and pay $800. And maybe some other steps. All I know is what I learned from reading the specs of my POCO and one other in my state (which has much 1/10 simpler regulations).
  • New way: NEM2 users are using THIS ONE HACK to expand their system, called multi-tariff with zero-export expansion, to add more solar without losing net metering. It's either $200 or $800 depending on whether it qualifies for the discounted IA fee.
Both require you to pass inspection with AHJ of your equipment, so you can't use unlisted / non 9540 configs.
 
Nevermind I did some searching and found what I was looking for.
 
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Ah I see now that you said "without a permitting process."

Missed that part. Either way, it's not well known that zero export is allowed with an agreement in a lot of places.
 
ricardocello said:
Though I think if a power systems engineer really tried to minimize the latency in their design, it could be greatly improved over what we have today.
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This is theoretically an interesting point. (As I have said on other threads) My headcanon is that the latency is terrible on a lot of zero-export today because most of those systems are either designed for customers with interconnection agreements, or for the previous era when utilities didn't check as much. In both those cases, there is no need to be fast.

Smart meters can sample very quickly (like, kilosamples/second or better). Given that, the control response latency of the zero export has to be fast enough that it can hide under the floor of the noise filtering and false positive prevention algorithms.
 
zanydroid said:
This is theoretically an interesting point. (As I have said on other threads) My headcanon is that the latency is terrible on a lot of zero-export today because most of those systems are either designed for customers with interconnection agreements, or for the previous era when utilities didn't check as much. In both those cases, there is no need to be fast.

Smart meters can sample very quickly (like, kilosamples/second or better). Given that, the control response latency of the zero export has to be fast enough that it can hide under the floor of the noise filtering and false positive prevention algorithms.
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Maybe some company will make this their next killer feature and charge appropriately for it.
Pretty clear there is a market for it. Call it True Zero Export or something.
 
ChrisG said:
Only actual evidence I have that the 6000xp I have doesn’t anything back to grid is: Neighbor hooked up a Solark and POCO swung by the same day and made him disconnect. My XP has been running for months without incident.
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Do you all have smart meters on individual properties, or did they detect the issue using coarser grain monitoring than that?
 
ricardocello said:
Pretty clear there is a market for it. Call it True Zero Export or something.
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By the time they develop get it on the market, you'll be able to buy a 9540/other code compliant system for only 0-25% more than a high quality unlisted system. And you can't exactly make much money in the US on the margin between this pricepoint and unsafe garbage.
 
zanydroid said:
Wow, that is amazingly efficient on the part of the POCO.
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Yeah this is at my cabin area in TN, little co-op/TVA POCO. At my primary home, POCO only allows buy all/sell all interconnect which is absolutely stupid and useless.
 
zanydroid said:
Do you all have smart meters on individual properties, or did they detect the issue using coarser grain monitoring than that?
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All smart meters. Gridsteam RF FOCUS AXRe. I can see very granular power usage as well as temperature real time via web.
 
ChrisG said:
All smart meters.
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OK. This sort of plays into my pet theory that the companies that make smart meters with really fancy sampling capabilities and OTA software upgrades (I found out about this when I googled the marketing literature for the smart meter I have), are leveraging those to sell data mining features to POCO to find things like random interconnections.
 
I
zanydroid said:
OK. This sort of plays into my pet theory that the companies that make smart meters with really fancy sampling capabilities and OTA software upgrades (I found out about this when I googled the marketing literature for the smart meter I have), are leveraging those to sell data mining features to POCO to find things like random interconnections.
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Yup. I edited my post while you were replying.

Gridsteam RF FOCUS AXRe. I can see very granular power usage as well as temperature real time via web.
 
cs1234 said:
Anything with a UPS mode that is fast enough to keep your PC from shutting off can possibly backfeed can't it? Including some regular AGM included inside UPS's? Or does it depend on the internal design of the inverter? Are some of them capable of keeping their internal inverter synced up to the grid signal for fast switch over back and forth, but not possibly leak even the tiniest trace amount?

I was pretty sure we came to the conclusion that the only way to "guarantee" no backfeed is to do double conversion.
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The 6000xp does it by all-or-nothing with the grid. The EG4 3000 is the interesting case. It can supplement from grid. If you have a large load being supplemented from grid, and load cuts off suddenly, then what happens? It is not an exporting inverter.
 
ricardocello said:
Maybe some company will make this their next killer feature and charge appropriately for it.
Pretty clear there is a market for it. Call it True Zero Export or something.
Click to expand...
I'm guessing that it would have built in double conversion.
As I don't think that it's possible to control it fast enough, any other way.
 
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zanydroid said:
I read that thread as saying, "Don't turn on hybrid/grid assist features via backdoor, it's not US approved for that".

I guess that also means the hardware is capable of being flipped in this mode, so it's possible a bad firmware could cause it to happen.
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That's what I got out of it as well, fortunately it doesn't seem that option is accessible by standard users.
 
zanydroid said:
Ah I see now that you said "without a permitting process."

Missed that part. Either way, it's not well known that zero export is allowed with an agreement in a lot of places.
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Yes, like in some European countries and their balcony solar. Except I don't even care about exporting back into the grid (other than spurious export). I just want zero export solar type systems to be allowed without permit under a certain size. I would be willing to put forth a requirement that some type of "pre-approved" grid-tied generator outlet be installed on all new construction and allowed to be installed by a homeowner or electrician for these devices to plug into in existing construction.

I think that the fire regs and wind load regs need to be loosened quite a bit also on batteries and panels.

If I want to put some batteries in my garage, I shouldn't have to put huge concrete / metal pillars into the floor to keep a car from running into them.. that's asinine.

Solar panel mounting shouldn't have to withstand 125mph winds.. give me a break.

If you think about it, we wouldn't even have electricity, or telephones, or any other number of modern technologies if we had all these rules and regulations in the first place.. nobody would have been able to invent squat without being some gigantic licensed business entity first.
 
timselectric said:
Yes
In order to export, it must be running in parallel with the grid.
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By parallel, do you mean it can blend grid and self-gen power? So if you want an off-grid inverter that has the blend function, there is still a chance that export can happen?
 
jeff88 said:
By parallel, do you mean it can blend grid and self-gen power? So if you want an off-grid inverter that has the blend function, there is still a chance that export can happen?
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Parallel means the grid AC and the inverter output AC touch directly.

This can happen with systems that don't blend, too, EG active standby.

The relay/contactor stuff people talk about refers to systems where the outputs are air gapped by some sort of isolation. For instance, an inverter in UPS mode can be pre-synchronized to grid (by letting the inverter "see" the waveform via voltage sensors), but the inverter can be kept disconnected from the output while the output is connected to grid.
 
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