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