We're adding a second system(with PWs) and the question has come in as to if we want to keep the original system on NEM 1.0 or convert it to NEM 2.0 with the new system. I can find very little opinion/feedback on this but the one study I did find seemed to lean towards the 2.0 option. Do any of you have any wise words?
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NEM 2.0 vs NEMMT
- Thread starter Magiken
- Start date
I can't think of a reason why NEM 2.0 would be advantageous over NEM 1.0 presuming that you can install the same system if you keep the old system on NEM 1.0. What are the reasons given for switching to 2.0? It would seem to me that you end paying more NBCs if you do so. Is it a metering issue?
Here's the explanation given for the two options:
(1) NEMMT (NEM Multiple Tariff)
Maintain your original system including currently locked-in rates under NEM 1.0 for the remainder of your allowed 20 years while adding the new generation (system) under NEM 2.0 by installing a Net Generation Output Meter (NGOM) at your own expense, which can cost up to $6,000. You will essentially own two systems, each running on its own separate meter per assigned NEM tariff. This option will "grandfather" the NEM 2.0 system under the NEM 2.0 tariff for a full 20 years, beginning from the issuance of the PTO (permission to operate) for this project. Utility states estimated cost for customer that will be determined by the utility. This option will not be financed by Tesla in any way.
OR
(2) NEM2
Place both the original NEM 1.0 system and the added generation under the NEM 2.0 tariff. Choosing this option preserves the original PTO date from the NEM 1.0 system as relates to the grandfathering provision. Both systems will function together per NEM 2.0 regulations and tariff. There are no added costs for this option.
(1) NEMMT (NEM Multiple Tariff)
Maintain your original system including currently locked-in rates under NEM 1.0 for the remainder of your allowed 20 years while adding the new generation (system) under NEM 2.0 by installing a Net Generation Output Meter (NGOM) at your own expense, which can cost up to $6,000. You will essentially own two systems, each running on its own separate meter per assigned NEM tariff. This option will "grandfather" the NEM 2.0 system under the NEM 2.0 tariff for a full 20 years, beginning from the issuance of the PTO (permission to operate) for this project. Utility states estimated cost for customer that will be determined by the utility. This option will not be financed by Tesla in any way.
OR
(2) NEM2
Place both the original NEM 1.0 system and the added generation under the NEM 2.0 tariff. Choosing this option preserves the original PTO date from the NEM 1.0 system as relates to the grandfathering provision. Both systems will function together per NEM 2.0 regulations and tariff. There are no added costs for this option.
I think the nom bypassable charges are the big thing. We are on NEM 2.0 and even though I currently have a $300 credit with the power company, I still have to pay them $34/month.
Here's the closest thing I can find to a study on the topic: Investigating the Effect of California’s NEM 2.0 on Solar Savings
FYI: We're in the PG&E territory
FYI: We're in the PG&E territory
kev1n
Active Member
NEM 1.0 is better than NEM 2.0
you will have to do some math to figure out if a new meter will cost you more in the long run than the savings you get for having one system on NEM 1.0
they will not allow you to just add onto the current system with NEM 1.0? is it due to the size of the 2nd system?
you will have to do some math to figure out if a new meter will cost you more in the long run than the savings you get for having one system on NEM 1.0
they will not allow you to just add onto the current system with NEM 1.0? is it due to the size of the 2nd system?
NEM 1.0 is no longer in use, as of July 2017. So your only options are those above, unless your system is over 1 MW, then there are some additional rules.
OK, here's my understanding:
With NEM 1.0, the monthly bill is determined by looking at the total net usage within a given TOU category and calculating the debit/credit accordingly. NEM 2.0, in contrast, requires looking all of the interval data (every 15 minutes, I think) within the given TOU category, and you get a slightly lower credit for the intervals showing net export than the debit you pay for the intervals showing net usage. The difference in rates reflects the Non-Bypassable Charges, a fee for the power company delivering energy to you during one interval that you don't get credited back when you deliver energy to the power company during another interval.
With an existing NEM 1.0 generator, you are limited in how much generation you can add and stay under NEM 1.0. The limit is 1.0 kW, or for systems bigger than 10 kW, 10% of the system size. If you add more generation than that, the new generation has to be under NEM 2.0. So one option is just to switch everything over to NEM 2.0.
The other option is to maintain separate NEM 1.0 and NEM 2.0 systems, but this requires a second meter (called a Net Generation Output Meter, NGOM). I don't know if the utility side of the NGOM is typically connected before or after the main meter, but in terms of data capture, it doesn't matter; the two are equivalent via some subtraction.
More to follow; I'm actually on hold with PG&E trying to find out how the NBCs work when you have two meters and both a NEM 1.0 system and a NEM 2.0 system.
Cheers, Wayne
With NEM 1.0, the monthly bill is determined by looking at the total net usage within a given TOU category and calculating the debit/credit accordingly. NEM 2.0, in contrast, requires looking all of the interval data (every 15 minutes, I think) within the given TOU category, and you get a slightly lower credit for the intervals showing net export than the debit you pay for the intervals showing net usage. The difference in rates reflects the Non-Bypassable Charges, a fee for the power company delivering energy to you during one interval that you don't get credited back when you deliver energy to the power company during another interval.
With an existing NEM 1.0 generator, you are limited in how much generation you can add and stay under NEM 1.0. The limit is 1.0 kW, or for systems bigger than 10 kW, 10% of the system size. If you add more generation than that, the new generation has to be under NEM 2.0. So one option is just to switch everything over to NEM 2.0.
The other option is to maintain separate NEM 1.0 and NEM 2.0 systems, but this requires a second meter (called a Net Generation Output Meter, NGOM). I don't know if the utility side of the NGOM is typically connected before or after the main meter, but in terms of data capture, it doesn't matter; the two are equivalent via some subtraction.
More to follow; I'm actually on hold with PG&E trying to find out how the NBCs work when you have two meters and both a NEM 1.0 system and a NEM 2.0 system.
Cheers, Wayne
Last edited:
kev1n
Active Member
i understand its no longer available but if im understanding this correctly, making any change at all to a NEM 1.0 system means you have to move to 2.0 aside from adding a new meter?
OK, 45 minutes and 3 people at PG&E Solar Customer Service Center failed to provide an answer on how NBCs work with two meters and a joint NEM 1.0 / NEM 2.0 system. Perhaps I will hear back from them as promised.
Here's my guess, but there are a number of other possibilities:
Call the old meter A; it shows (NEM 1.0 generation - consumption), where net generation is positive (opposite the usual convention). Call the new meter B; it shows the NEM 2.0 generation (also positive). And call the total T = A+B.
If T is negative (net consumption) for an interval, you are charged at the full retail rate for the consumption.
If T is positive (net generation) for an interval, and T < B, then you are credited at the reduced retail rate for the NEM 2.0 generation.
If T is positive for an interval and T > B, then you are credited B at the reduced retail rate for NEM 2.0 generation, and (T-B) at the full retail rate for NEM 1.0 generation.
Again, this is only a guess, but it seems to me that it is the only semi-reasonable algorithm when the new meter just meters the NEM 2.0 system production.
Cheers, Wayne
Here's my guess, but there are a number of other possibilities:
Call the old meter A; it shows (NEM 1.0 generation - consumption), where net generation is positive (opposite the usual convention). Call the new meter B; it shows the NEM 2.0 generation (also positive). And call the total T = A+B.
If T is negative (net consumption) for an interval, you are charged at the full retail rate for the consumption.
If T is positive (net generation) for an interval, and T < B, then you are credited at the reduced retail rate for the NEM 2.0 generation.
If T is positive for an interval and T > B, then you are credited B at the reduced retail rate for NEM 2.0 generation, and (T-B) at the full retail rate for NEM 1.0 generation.
Again, this is only a guess, but it seems to me that it is the only semi-reasonable algorithm when the new meter just meters the NEM 2.0 system production.
Cheers, Wayne
GenSao
Member
Agreed. From what I have read NEM 1.0 is generally better than NEM 2.0 from a pure solar panel only prospective. Since a new meter is needed for part of your system to stay on the old rate schedule with NEM 1.0, moving to a new rate schedule with NEM 2.0 may be more cost effective. Your specific utility rate schedule will dictate the cost effectiveness.
I am in PG&E Land. The most cost effective would be on an EV rate schedule (EV-A) with solar and batteries mitigating the peak (Summer $0.455/kWh) and partial-peak rate (Summer $0.251/kWh). I shift power use to off-peak rate (Summer $0.123/kWh) to night to charge EVs, dry laundry, and charge other batteries.
For PG&E, non-bypass charges are approximately $0.0211/kWh based on:
$ 0.0141 Public Purpose Program Charge
$ 0.0002 Nuclear Decommissioning Charge
$ 0.0013 Competition Transition Charge
$ 0.0055 Department of Water Resources Bond Charges
$ 0.0002 Nuclear Decommissioning Charge
$ 0.0013 Competition Transition Charge
$ 0.0055 Department of Water Resources Bond Charges
Do consider the cost of round-trip power loss of 11% (100% - 89% Efficiency) for a Powerwall to defer non-bypass charges at partial-peak or off peak rates. In general you'll still come out ahead.
Partial-peak rate, Summer $0.251/kWh x 11% = $0.0276/kWh
Off-peak rate, Summer $0.123/kWh x 11% = $0.0135/kWh
Off-peak rate, Summer $0.123/kWh x 11% = $0.0135/kWh
Furthermore, participation in demand response programs such as Ohmconnect may be useful to you. If interested, a referral link is provided. It is not required to sign up.
P.S. Upon reflection, the algorithm I propose is fair, in the sense that it makes an existing NEM 1.0 customer's incentive to add solar the same as any new NEM 2.0 customer. Namely, generation that offsets existing consumption reduces one's bill at the full retail rate, while generation that leads to export is credited at the NEM 2.0 reduced retail rate.
So that is probably how it works.
Cheers, Wayne
So that is probably how it works.
Cheers, Wayne
Thanks GenSao and wwhitney for the info. This is very helpful. We certainly sympathize with trying to get a clear answer out of anyone at PG&E, or Tesla for that matter. And yes, we also recognize the EV plan and when we use power is probably the biggest variable here that will ultimately determine 'success' versus the NEM choice.
OK, now I'm not sure how NBCs work. So here's a simple example:
Say there's just 1 tier/TOU category and a billing period with only 2 non-zero intervals. The total rate is $0.10/kWh, of which NBCs are $0.02/kWh. If one interval shows 3 kWhs produced, and the other interval shows 3 kWhs consumed, then obviously the charge is $0.06, just from the NBCs. Now change the production figure to 2 kWhs, keeping the consumption figure at 3 kWhs. Is the bill $0.14 (that is, 3 * $0.10 - 2 * $0.08), or is the bill $0.10 (that is, max((3-2) * $0.10, 3 * $0.02))?
My previous comments were based on the understanding it would be $0.14, so if it would actually be $0.10, I'll need to reconsider everything.
Cheers, Wayne
Say there's just 1 tier/TOU category and a billing period with only 2 non-zero intervals. The total rate is $0.10/kWh, of which NBCs are $0.02/kWh. If one interval shows 3 kWhs produced, and the other interval shows 3 kWhs consumed, then obviously the charge is $0.06, just from the NBCs. Now change the production figure to 2 kWhs, keeping the consumption figure at 3 kWhs. Is the bill $0.14 (that is, 3 * $0.10 - 2 * $0.08), or is the bill $0.10 (that is, max((3-2) * $0.10, 3 * $0.02))?
My previous comments were based on the understanding it would be $0.14, so if it would actually be $0.10, I'll need to reconsider everything.
Cheers, Wayne
GenSao
Member
Using your example under NEM 2:
3 kWh consumed ($0.10 + $0.02) x 3 = $0.36; Less 3 kWh produced ($0.10) x 3 = $0.30; Equals $0.36 - $0.30 = $0.06 Charge
3 kWh consumed ($0.10 + $0.02) x 3 = $0.36; Less 2 kWh produced ($0.10) x 2 = $0.20; Equals $0.36 - $0.20 = $0.16 Charge
For refrence, under NEM 1:
3 kWh consumed ($0.10 + $0.02) x 3 = $0.36; Less 3 kWh produced ($0.10 + $0.02) x 3 = $0.36; Equals $0.36 - $0.36 = $0.00 Charge
3 kWh consumed ($0.10 + $0.02) x 3 = $0.36; Less 2 kWh produced ($0.10 + $0.02) x 2 = $0.24; Equals $0.36 - $0.24 = $0.12 Charge
Non bypass charges are fees that can not be reversed by solar generation credits.
GenSao's numbers are correct.
Under NEM 2.0, the actual rates are:
$0.10/kWh for production, $0.12/kWh for consumption
So: -$0.30 + $0.36 = $0.06 v -$0.20 + $0.36 = $0.16
For us under SCE (TOU-A summer):
off-peak: consumption: $0.12382 v generation: $0.10463
shoulder: consumption: $0.27646 vs generation: $0.25727
peak: consumption: $0.47929 vs generation $0.4601
Solution is to arbitrage against the peak generation rate by converting off-peak kWh -- to offset monthly NBCs.
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