480/277 WYE service to 120/240 Single phase

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So how does a 3 phase meter work?

Um...however they tell you! ;)
It can record the imbalance correctly, or run only one way depending on the situation judging by the italic part.

2. Normally, for installations with credit metering the connection of the Company’s PT
metering transformers is on the generator side of the CTs. The instantaneous
relative polarity of metering transformers is critical to proper operation. CTs are
polarized such that the polarity dot or marking is on the Company side.

3.3.2 Billing and Credit Metering
1. The Company will specify the quantity, type, rating, connections, location and
arrangement of all equipment required for the metering of the Generator-owner’s
service inclusive of the sale and/or purchase of energy as well as the monitoring of
compliance with all applicable laws, regulations and contracts. Individual kWH
meters either will be equipped with a detent to prevent reverse registration, or will be
capable of bi-directional measurement.


2. A metering system will be installed to continuously record kilowatt-hours (kWH) on a
time-differentiated basis. (To and From Company), and depending on magnitude of
Generator-owner’s load and/or generation, kilowatt demand (kW) (From Company),
and kilovar demand (kVAR) (From Company). For those installations having a “Buy
All-Sell All” purchase agreement contract in effect, additional kilowatt-hour (kWH)
meters will also be installed on the output of the generator(s). Also, a recorder will
be installed.
http://www.nationalgridus.com/non_html/shared_constr_esb756.pdf
 

kwired

Electron manager
Location
NE Nebraska
quote_icon.png
Originally Posted by PVfarmer

So if inverter phase C is only connected to xfmr Z, there would have to be another meter there for the other customer- then the inverter phase C would go to that 2nd customer load while A and B from inverter are going to customer 1. Right?:?




Ok, but then what happens if there is no "other customer" load on phase C during daylight hours?
Inverter phase C goes to the step-up to grid xfmr.
I don't get why you'd want to have a PV system, but only connect 2 phases of it to the load instead of three- you'd be taking/paying for power from the grid 33% more of the time by only using 2 phases of the inverter(s).
Depending on the load of course- if it was small, maybe wouldn't matter so much, like the OP's 40A 240V welder, 9600 watts = 11.6A at 480/277V, so that's 27.5% of the 42.2A (3 phase) that the OP's 2 inverters are putting out at maximum.

That means the one phase of the inverter would only be supplying the welder 100% around midday.
If he used all three phases from the inverters, the PV would be running the welder 100% until total output dropped below 27.5%.

This is a farm we're talking about here- farmers in general are not into paying more for something (grid power) when they can get it for less (PV Power) :)
If there is no other customer on Phase C you have a pretty small grid. Most of the continental US is interconnected enough you are connected to most of everyone else to some extent.

Also with phase balancing of load vs output of on site produced power - the POCO doesn't send you a separate bill for usage on each phase, you get one bill with net kWhrs. If 1 kWhr goes out to grid on C phase but you end up drawing .25 kWhrs each on A and B during that same time period then .5 kWhr is the net recorded as going out. May be a little more complicated then that, but trying to keep it simple for explanation. Bottom line is you are billed for what kWhrs is delivered to you, anything you put into the grid is simply deducted from what you take out. If you put more in then you take out then the POCO owes you instead of you owing them - again some complexities may go with that but that is the basics.
 
If there is no other customer on Phase C you have a pretty small grid. Most of the continental US is interconnected enough you are connected to most of everyone else to some extent.

Also with phase balancing of load vs output of on site produced power - the POCO doesn't send you a separate bill for usage on each phase, you get one bill with net kWhrs. If 1 kWhr goes out to grid on C phase but you end up drawing .25 kWhrs each on A and B during that same time period then .5 kWhr is the net recorded as going out. May be a little more complicated then that, but trying to keep it simple for explanation. Bottom line is you are billed for what kWhrs is delivered to you, anything you put into the grid is simply deducted from what you take out. If you put more in then you take out then the POCO owes you instead of you owing them - again some complexities may go with that but that is the basics.

Right. But I think Wayne was talking about another customer on the LV of one POCO xfmr.
Which leads to an interesting question-
The POCO here offers 2 meter service for single phase, but not three phase as far as I can tell.
2-6 gang service they call it- there are L1 and L2 coming from a xfmr, and L1 is connected to L1 on both meters, L2 to L2 on both meters.
There's a diagram here on page 85.
https://www.nationalgridus.com/non_html/shared_constr_esb750.pdf

Now, I can see how if there is PV power coming from *both* L1 and L2 of one meter, it'll be going out through one meter back through the other meter to the other customer load.
But they don't offer the dual meter thing for 3 phase service, I can see how with two meters phases A and B would be going out to grid and phase C could be going to the load on C- but that C would be metered by a PV output meter, then go through the "other customers" meter...so the POCO would be charging them for that power on C, but the producer would actually be getting EXTRA credit for producing it, since it was produced with no usage (on the PV producer's utility meter phase C) to offset it.

I think that would be ok if all prices were equal (netmetering) but if there was a higher than retail incentive...things wouldn't work.
 

kwired

Electron manager
Location
NE Nebraska
Right. But I think Wayne was talking about another customer on the LV of one POCO xfmr.
Which leads to an interesting question-
The POCO here offers 2 meter service for single phase, but not three phase as far as I can tell.
2-6 gang service they call it- there are L1 and L2 coming from a xfmr, and L1 is connected to L1 on both meters, L2 to L2 on both meters.
There's a diagram here on page 85.
https://www.nationalgridus.com/non_html/shared_constr_esb750.pdf

Now, I can see how if there is PV power coming from *both* L1 and L2 of one meter, it'll be going out through one meter back through the other meter to the other customer load.
But they don't offer the dual meter thing for 3 phase service, I can see how with two meters phases A and B would be going out to grid and phase C could be going to the load on C- but that C would be metered by a PV output meter, then go through the "other customers" meter...so the POCO would be charging them for that power on C, but the producer would actually be getting EXTRA credit for producing it, since it was produced with no usage (on the PV producer's utility meter phase C) to offset it.

I think that would be ok if all prices were equal (netmetering) but if there was a higher than retail incentive...things wouldn't work.
Meters only care about kWhrs, they don't care if rate of what comes in is different then rate going out.

Throw out the PV for a moment and go with a traditional three phase service - if you only have load on phases A and B it meters total kWhrs used even if C phase is never loaded. Now if you interconnected some other source on load side of that meter without agreement with POCO they may not be all that happy about it, but any power that finds it's way to the line side will be a reduction in what that meter ends up registering compared to what was actually used on the premises. Send more out then you take in and you will have a lower accumulative reading then you did the last billing which will raise a red flag if you have no agreement to sell power to the utility, or make them think you used so much power the meter went past it's limits and started over from zero again - which will get your attention when you look at the dollar amount of the bill.
 
Meters only care about kWhrs, they don't care if rate of what comes in is different then rate going out.

Throw out the PV for a moment and go with a traditional three phase service - if you only have load on phases A and B it meters total kWhrs used even if C phase is never loaded. Now if you interconnected some other source on load side of that meter without agreement with POCO they may not be all that happy about it, but any power that finds it's way to the line side will be a reduction in what that meter ends up registering compared to what was actually used on the premises. Send more out then you take in and you will have a lower accumulative reading then you did the last billing which will raise a red flag if you have no agreement to sell power to the utility, or make them think you used so much power the meter went past it's limits and started over from zero again - which will get your attention when you look at the dollar amount of the bill.

I'm following that part, but what about this diagram:

Customer A is the one connected to phase A on the right side, with the PV system.
Side note: I think that's what the OP here would want to to- a 12.5 or 15kVA single phase 277V to 120/240 xfmr connected to one phase of his Tripowers.

Customer B is the same thing, but connected to phase C on the left where the arrow is pointing.

Seems like Cust A would get credit for PV production *AND* reduce the use recorded by the middle meter there- that's not fair...to the POCO.
The POCO is getting paid retail by Cust B, but for power that Cust A has both gotten paid for producing *and* subtracted from their bill.
I think.
Please excuse the 3 pole breaker with empty pole- that should be a 2 pole.
TWOCUSTOMER.jpg
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Seems like Cust A would get credit for PV production *AND* reduce the use recorded by the middle meter there- that's not fair...to the POCO.
The POCO is getting paid retail by Cust B, but for power that Cust A has both gotten paid for producing *and* subtracted from their bill.
Your concern has nothing to do with the phases. If I am reading the diagrams correctly, Customer A has a meter on his service, and an additional downstream meter on his PV production only. In such a case, every kWh produced by Customer will read on the PV meter and reduce his usage on the overall meter. The POCO knows this and they will bill accordingly, depending on the rate structure. [For example, if this were Austin, TX, they would add the two meters together to get the total consumption, and then credit for the PV production per the PV meter.]

Cheers, Wayne
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
...if this were Austin, TX, they would add the two meters together to get the total consumption, and then credit for the PV production per the PV meter.
True, as long as you take into account that the utility meter reading can be a negative number.
 

kwired

Electron manager
Location
NE Nebraska
Is far right meter (the one on the PV equipment output) a utility company meter or just for the users own information?

The center meter will register net of customer "A", if customer A uses more power then they put into the grid they have to pay an energy bill, if they put more in the grid then they take out they have a credit energy bill.

Customer B pays for kWhrs used regardless of whether they came from utility or the PV system of customer A, once those kWhrs pass the net meter as "credit energy" to customer A that energy belongs to the POCO.

If Customer A is billed a different rate for consumption then they are compensated for input to the grid - I'm sure it gets more complex. If that is what the meter on the PV is all about then I can maybe see your confusion. Customer A would be getting credit for energy they are producing even if they are using all of it at their premises. I would think the POCO's would want to set it up so that they only monitor what is introduced into the grid, and not all the production even if it never enters the grid. As is drawn I can see them paying you to use what you produced, when I'm sure all they want is to pay for what you put into the grid. Again customer B only has consumption and never knows how much of their energy came from the PV production vs from the grid.
 
Is far right meter (the one on the PV equipment output) a utility company meter or just for the users own information?

The center meter will register net of customer "A", if customer A uses more power then they put into the grid they have to pay an energy bill, if they put more in the grid then they take out they have a credit energy bill.

Customer B pays for kWhrs used regardless of whether they came from utility or the PV system of customer A, once those kWhrs pass the net meter as "credit energy" to customer A that energy belongs to the POCO.

If Customer A is billed a different rate for consumption then they are compensated for input to the grid - I'm sure it gets more complex. If that is what the meter on the PV is all about then I can maybe see your confusion. Customer A would be getting credit for energy they are producing even if they are using all of it at their premises. I would think the POCO's would want to set it up so that they only monitor what is introduced into the grid, and not all the production even if it never enters the grid. As is drawn I can see them paying you to use what you produced, when I'm sure all they want is to pay for what you put into the grid. Again customer B only has consumption and never knows how much of their energy came from the PV production vs from the grid.

Thanks everybody, I think I might in fact have it here!
Ok, pretty sure the far right meter is "customer owned", but the POCO also uses it to calculate the bill.
So registering net on all 3 phases with that setup leads to that problem you also see.

With the previous diagram, you'd have to make the main 3 phase meter run one-directionally- it would only record Customer A use on the 2 phases, and NOT net-in the phase C PV output, so you could subtract the usage from the PV output meter total- if the usage was zero (or negative) on the utility meter due to low usage/large PV, then Cust A would get paid for all the PV output measured by the PV meter (minus the load which was reduced by *some* of the PV output, which caused that load to not register on the utility meter)...
Making sense there so far?

But, scratch that last diagram, because....
that is only allowed for 208/120 three phase service- because the meters there are "hot sequenced", meaning meters are on the POCO xfmr side of the customer's MDP/disconnect.
That's not cool- for the 480/277 service we are talking about, the utility meter has to be COLD sequenced, meaning on the *load* side of the MDP.

That's going by what it defines on pages 30, 31 and 33 here, and the chart of services on pg. 71.
https://www.nationalgridus.com/non_html/shared_constr_esb750.pdf

So! Here's another one- the previous diagram was ALSO a load side PV connection! Hence my confusion!! :?

Try this-
If the larger green meter is where is is pictured, on phases A B and C and the PV customer loads are on B and C, it would not be cool if the meter ran bi-directionally and netted the total- then phase A would be counted twice, as it isn't going to a load at all, just going out through the PV meter and then again thru the green one to the grid.

To fix that, the larger green meter would have to go only on phases B and C- then phase A would be measured by the PV meter, and phases B and C would show correctly the net of flow to/from grid.
You'd just subtract the usage (or subtract the output if any as a negative number) shown by the green meter from the total on the PV output meter to find how much PV went to grid.

But- if customer PV was using all 3 phases for the load, the green meter *could* be bi-directional.

And if the green meter was where the green arrow is pointing instead...maybe it should measure output TO the grid, as those smaller meters would take care of the usage for each customer- if it was where the green arrow is pointing and reading output, it should come out equal to the PV output meter total minus (Cust A usage plus Cust B usage).
Maybe?
TWOCUSTOMER2.jpg
 
IMO you are making this far more complicated than it needs to be.

I wish that was my fault- but I have to follow one of these rules in this case.

document that one of the options
specified in paragraphs (e)(1) through
(3) of this section is met:
(1) Installation of a second meter (or
similar device) that results in all of the
energy generated by the RES being used
for non-residential energy usage;
(2) Certification is provided in the
application that any excess power
generated by the RES will be sold to the
grid and will not be used by the
Applicant for residential purposes; or
(3) Demonstration that 51 percent or
greater of the energy to be generated will
benefit the Rural Small Business or
agricultural operation. The Applicant
must provide documentation that
includes, but is not limited to, the
following:

1 and 3 are both impossible, so it has to be 2.

Would you have any ideas about what a "similar device" mentioned in #1 would be?
It's the government, so of course it's confusing- a meter just measures kWh, it doesn't control the flow of power- I'm not familiar with any device that would make PV power go out to grid while bringing grid power in at the same time.
So with #2, as long as the power is recorded as being sold to the grid, it shouldn't matter to the gov if the power is going out to MV and then back to the residence, or staying on the LV side.
Also, with single phase service, you get two meters side by side in one enclosure- three phase meters are separated, but they have to be wired in the same configuration as the single phase meters if you're gonna feed out through one and in through the other.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I wish that was my fault- but I have to follow one of these rules in this case.

Physically, I mean. It's just a parallel circuit with the utility acting as a voltage source and the inverter acting as a current source, and the power flows to the load. The transformers are virtually transparent to power; they just swap voltage for current.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
a meter just measures kWh, it doesn't control the flow of power- I'm not familiar with any device that would make PV power go out to grid while bringing grid power in at the same time.
Indeed, the idea is nonsensical. That regulation can only be about the arrangement of meters (or certifying that the service has no residential loads, perhaps). I think for the purpose of reading it you should just consider "the grid" to start at the service beyond all the meters.

So I would think the easiest way to comply would be to connect the PV through its own meter to a line side tap ahead of the consumption meter. Transformers just don't enter into it at all.

Let me make the caveat that you have quoted a small section of an unknown regulation, so there may be more to the story than it currently appears.

Cheers, Wayne
 
quote_icon.png
Originally Posted by PVfarmer
I wish that was my fault- but I have to follow one of these rules in this case.

ggunn-
Physically, I mean. It's just a parallel circuit with the utility acting as a voltage source and the inverter acting as a current source, and the power flows to the load. The transformers are virtually transparent to power; they just swap voltage for current.


You're right- it is sorta simple-
The options are:
With single phase service and two meters, power will go out one meter and right back in the other. Done.
With 3 phase, you get a main service, either 480/277 or 208/120. So there's a main 3 phase meter- you can get another account, but it has to be coming from 2 legs of that 3 phase service- you get 277/480 or 120/208 single phase, and the meter is wired the same way a 120/240 single phase meter is wired- 2 hot legs and a neutral.

So you can't physically have the power going out to grid from the main 3 phase meter and then back to a the separate single phase meter- if you netted the input/ouput on a main meter, there'd be no reason to have a usage meter on either load, there would only be one bill. You could set it up that way, power would be going straight from PV to both PV and non-PV customer and reducing input on the main meter, but that wouldn't satisfy the "rules".
The main meter has to measure the PV output and the PV customer usage and apply that to a bill before it goes to the non-PV customer.

If the PV customer was connected through a different main pole, the output would go to grid, down the line to the next pole, and to the non-PV customer's service.
So this metering setup basically does that, while skipping the poles- since the meters are "cold", the power can go through one meter reading net, then another reading non-PV usage, while not going to the main service panel.
The non-PV customer will be paying the POCO retail price for power that the POCO has already paid the PV customer for producing either way- to me, it seems like keeping the power on the LV side is like a win-win type deal for both customers and POCO.


So I would think the easiest way to comply would be to connect the PV through its own meter to a line side tap ahead of the consumption meter.

Let me make the caveat that you have quoted a small section of an unknown regulation, so there may be more to the story than it currently appears.
Yes, line-side would simplify things- but Im not sure if line-side input is OK when the meters have to be "cold".
If the PV output meter is PV-side of the PV disconnect it would be cold. (Line-side would be the dotted red line in the 2nd diagram.)
And the green line is a load-side PV connection.
So if the PV was line-side and the meter was at the green arrow (that would be a plain consumption meter like you said), you'd be subtracting the non-PV customer use from the PV output for the bill- not the way the gov wants it.
If the PV was load side, you'd want the larger green meter meter where it is, to net the PV customer's usage AND PV output- then when applied to PV customer bill, it will be "paid for" by the grid before going to the non-PV customer.
:?

It's right here on page 79236!

http://www.rd.usda.gov/files/Final_Rule_REAP_122414.pdf
Residential
Comment: In commenting on the
interim final rule, two commenters
suggested alternatives to the residential
restriction on farms.
One commenter noted that the interim
final rule allows excess electricity to be
sold to the grid, but not to be used in
a farm-related residence. This means the
applicant can get some value for excess,
but not maximum value. It also means
that the utility makes a profit on selling
excess electricity generated from the
project even though they did not pay
any of the capital costs. The commenter
believes a better approach would be to
remove the residential restriction on
farms with only one meter or allow
applicant certification of non-use for
non-business purposes. Applicants
would show and affirm as part of a
simplified form that the farm operation
uses more energy on an annual basis
than the RES is projected to produce.
The other commenter supported the
restriction of funding residential RES or
EEI projects, but suggested allowing
prorating project cost to the non-
residential uses. According to this
commenter, many agricultural
producers wish to also power their
homes on their farmsteads with RES and
requiring a separate meter at additional
costs discourages these applicants from
applying. If we allowed them to size the
system accordingly, interconnect to all
load sources, but only provide funding
for business portion of their load
supported by appropriate
documentation, both the applicant and
the Agency would win.
Response: The Agency agrees with the
commenters that there should be more
flexibility to allow agricultural
producers to submit applications for
RES where the resulting power is shared
between the farm operation and the
farm residence. To this end, the final
rule provides applicants with three
options to qualify an RES project in
which a residence is closely associated
with and shares an energy metering
devices with the agricultural operation:
• Install a second meter (or similar
device) that results in all of the energy
generated by the RES to be used for non-
residential energy usage;
• Certify that any excess power
generated will be sold to the grid and
will not be used by the residence; or
• Demonstrate that 51 percent or
greater of the energy to be generated will
benefit the agricultural operation. If the
farm residence uses more than 49
percent of the energy, however, this
option would not apply.
Although not requested by the
commenters, the Agency has concluded
that rural small business seeking to
purchase RES that would provide
energy to the small business and the
business’ residence should be afforded
the same options, provided the
residence is located at the place of
business, and the Agency has
incorporated this in the final rule.
In addition, the Agency has revised
the eligible project cost provisions to
make clear as to what items associated
with these options qualify as eligible
project costs. Specifically, the following,
as applicable, are eligible project costs:
• The installation of the second
meter, and
• The portion of the project that
benefits the agricultural operation or
rural small business
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
With single phase service and two meters, power will go out one meter and right back in the other. Done.
With 3 phase [ . . . ] So you can't physically have the power going out to grid from the main 3 phase meter and then back to a the separate single phase meter
Why not? The wiring arrangement would be the same as the single phase service with two meters, except the 3 phase meter would have the extra POCO conductor going to it.

Yes, line-side would simplify things- but Im not sure if line-side input is OK when the meters have to be "cold".
Sure, why not?

If the PV output meter is PV-side of the PV disconnect it would be cold. (Line-side would be the dotted red line in the 2nd diagram.)
Sorry, I've lost track of which diagram you are referring to, so I'm having trouble following you. But if I understand correctly you just want to do the following (forgive the ASCII art):

Service --- 3 phase disconnect -- 3 phase PV production meter -- PV source
|
------- 1 phase disconnect -- 1 phase consumption meter -- 1 phase loads

Cheers, Wayne
 
quote_icon.png
Originally Posted by PVfarmer

1.you can't physically have the power going out to grid from the main 3 phase meter and then back to a separate single phase meter

Why not? The wiring arrangement would be the same as the single phase service with two meters, except the 3 phase meter would have the extra POCO conductor going to it.

2. Yes, line-side would simplify things- but Im not sure if line-side input is OK when the meters have to be "cold".

Sure, why not?

3. If the PV output meter is PV-side of the PV disconnect it would be cold. (Line-side would be the dotted red line in the 2nd diagram.)
Sorry, I've lost track of which diagram you are referring to, so I'm having trouble following you. But if I understand correctly you just want to do the following (forgive the ASCII art):

Service --- 3 phase disconnect -- 3 phase PV production meter -- PV source
|
------- 1 phase disconnect -- 1 phase consumption meter -- 1 phase loads

////
1. I don't think the wiring would be the same- with single phase, it's two meters side by side, with L1 and L2 from the grid connected to L1 and L2 of each meter- so power would go out one meter and right back in thru the other.
With 3 phase, I *think* you have one main 3 phase service meter that goes with the 3 (or single) POCO xfmr- so the power is being stepped down, and all three phases are metered, then the additional single phase customer gets 2 lines of that three phase for their single phase. It depends where the two wires for single phase are connected- if they're before (grid side) the 3 phase meter then it'll work- if they're after the 3 phase meter, it won't work.

2. I meant OK as in with the POCO. There *would* be two disconnects, the 100A main and the PV shut-off-so...you'd think it would be OK.

3. Not sure what the | means there.
But this diagram- if the PV was connected to grid at the red line (line side), and the larger green meter was at the green arrow, you'd be measuring the two loads as one.
But I'm trying to get two separately metered bills on the same service.
TWOCUSTOMER3.jpg
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
With 3 phase, I *think* you have one main 3 phase service meter that goes with the 3 (or single) POCO xfmr- so the power is being stepped down, and all three phases are metered, then the additional single phase customer gets 2 lines of that three phase for their single phase. It depends where the two wires for single phase are connected- if they're before (grid side) the 3 phase meter then it'll work- if they're after the 3 phase meter, it won't work.
Unless your POCO is weird, they will let you connect the service for the single phase meter before the 3 phase meter. What use is it to meter the power twice?

3. Not sure what the | means there.
That's just a vertical line, - is a horizontal line. I'm showing two different connections to the POCO service wires. In practice, I think you'd typically bring your service entrance conductors into a gutter/tap box, make your connections there, and then come out of the gutter separately to the three phase disconnect/meter and to the single phase disconnect/meter.

But this diagram- if the PV was connected to grid at the red line (line side), and the larger green meter was at the green arrow, you'd be measuring the two loads as one.
Yeah, that doesn't make sense, so don't do that. You're making this much more complicated than it needs to be. If you want to meter the consumption and the production separately, just arrange your meters so that one measures only production, and the other measures only consumption. That should fly with the POCO, assuming they are on board with this meter them separately idea.

BTW, this isn't really anything I have any experience with, I'm just trying to hopefully bring some order to a cluttered thread.


Cheers, Wayne
 
Unless your POCO is weird, they will let you connect the service for the single phase meter before the 3 phase meter. What use is it to meter the power twice?

That's just a vertical line, - is a horizontal line. I'm showing two different connections to the POCO service wires. In practice, I think you'd typically bring your service entrance conductors into a gutter/tap box, make your connections there, and then come out of the gutter separately to the three phase disconnect/meter and to the single phase disconnect/meter.

Yeah, that doesn't make sense, so don't do that. You're making this much more complicated than it needs to be. If you want to meter the consumption and the production separately, just arrange your meters so that one measures only production, and the other measures only consumption. That should fly with the POCO, assuming they are on board with this meter them separately idea.

Not sure if "before" is the right word there- isn't connecting the 2 accounts "side-by-side" the only right way to do it?

So...
Imagine the bolded T is actually upside down here, with the vertical connected to main switch- the left side of the horizontal goes to PV account, the right side goes to non-PV.
The .... .... ... is nothing- that just makes the ^ be in the right place.

Service
|
Main shut off box w/manual switch
|
T----> non-PV meter --- non-PV load panel
|
|<----> PV account meter (bidirectional) <----> load panel for PV account
. ........ ..... ..... ...... ...... ...... ...... ....... ...^<---- PV disconnect/PV meter/PV inverter


If the whole thing is a big T, with the service wires going into the main service switch at the bottom of the vertical leg of the T, you can't put any meter or combo of meters on the vertical- the meters have to go on the 2 lines that the top of the T makes to left and right- that's what I mean by side-to-side.
Any meter on the vertical would measure a load twice.
 

wwhitney

Senior Member
Location
Berkeley, CA
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Retired
Service
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Main shut off box w/manual switch
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T----> non-PV meter --- non-PV load panel
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|<----> PV account meter (bidirectional) <----> load panel for PV account
Sure, that will work. You don't need to have a "main shut off box", you could have individual disconnects after the "T" point but before each meter (since your POCO requires cold sequence meters). Which is what my diagram showed.

Cheers, Wayne
 
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