Balancing NEM buckets over the year

[GuyHall]

I now have 5 months of PG&E bills showing usage for On Peak, Part Peak and Off Peak. Using Tesla's Advanced setting in the app's customization setting and as expected tesla shifted grid load away from Peak and Part Peak, leaving most pull from the grid during off peak. After 5 months (3 winter, 2 summer), I see:

	Sum On Peak	Sum Part Peak	Sum Off Peak	Winter On Peak	Winter Part Peak	Winter Off Peak.
KWH	-800	-320	870	-1280	-660	874
~$ / KWH	$0.50	$0.39	$0.18	$0.37	$0.35	$0.18

PG&E's true up will return ~ $0.03 / excess kwh sent to PG&E so there's very little value in racking up On and Partial Peak KWH to the grid. My strategy is to shift grid usage to Peak and Partial Peak as I get close to my true up. I don't know the amount of solar I'll be getting during Nov - Feb, so I might not be able to "rebalance" the account.

Any suggestions on a general strategy for the year?

 

[getakey]

I don't want to do the math
What is your starting month and what is you NEM total to date? For example, I'm at -$840 since May 21. In Winter I will draw that down

 

[wwhitney]

PG&E's true up will return ~ $0.03 / excess kwh sent to PG&E so there's very little value in racking up On and Partial Peak KWH to the grid. My strategy is to shift grid usage to Peak and Partial Peak as I get close to my true up.

I don't understand why you'd want to shift usage to Peak and Partial Peak; there's no upside for you to do so. To be sure you understand how NEM works:

At the true-up, first each bucket will be multiplied by the bucket rate, and those are summed. If the sum is a net $ cost to you, you pay that. If it's a net credit, then a different computation is done: all the buckets are summed, and if you were a net kWh generator of energy for the year, you get ~$0.03 / kWh.

So if you are going to end up in the latter computation, time shifting usage/generation doesn't matter. And if you end up under the first computation, then you still want to minimize Peak and Partial Peak usage. Although if you end up with a net $ credit and being a net consumer of kWh, it doesn't matter.

One thing that does matter is that if you do forecast ending up with a net $ credit, for NEM2, it becomes useful to minimize NBCs. So at that point you may save money by switching your Powerwalls to Self Consumption. At least for part of the year; not sure if Self Consumption is clever enough to ensure that any non-self consumption occurs during Off-Peak, if not it is possible that Self Consumption would minimize NBCs while causing you not to end up with a net $ credit, a bad tradeoff.

Cheers, Wayne

 

[Redhill_qik]

PG&E's true up will return ~ $0.03 / excess kwh sent to PG&E so there's very little value in racking up On and Partial Peak KWH to the grid.

If you are in a PG&E area with a Community Choice Aggregator and are a net generator, as it appears that you are, then they pay more for the net generation than PG&E. It looks like you are in Placer County and may be in the Pioneer Community Energy service area. They only offer $0.005/kWh (16.7% more at $0.030/kWh) over PG&E wholesale rate, but at least it is more. The PCE rate range from Aug 2020 to July 2021 was $0.02679 (March 2021) to $0.03568 (July 2021).

 

[GuyHall]

I now have 7 months of PG&E bills showing usage for On Peak, Part Peak and Off Peak. Using Tesla's Advanced setting in the app's customization setting and as expected tesla shifted grid load away from Peak and Part Peak, leaving most pull from the grid during off peak. After 7 months (3 winter, 4 summer), I see:

	Sum On Peak	Sum Part Peak	Sum Off Peak	Winter On Peak	Winter Part Peak	Winter Off Peak.
KWH net over 7 mos.	-850	-400	600	-1700	-650	260
~$ / KWH	$0.50	$0.39	$0.18	$0.37	$0.35	$0.18

For 4 of the buckets, I had a net export. For two buckets, I was a net consumer. Overall I've exported a net of 2740 KWH to the grid.

First question: are there 6 buckets or buckets? Are On Peaks combined? Are Part Peaks combined? Are Off Peak combined? Or are summer and winter kept separate? If they are kept separate, I kind of screwed up here by using the batteries to shift too much load to summer's Off Peak, especially as now I'm past the summer season... I was thinking I could "rebalance" during the winter.

Assuming my worst case, looks like I need to shift load for the winter months to zero as much as possible each winter bucket.

Comments?

 

[miimura]

Month by month your buckets are converted to dollars. The net kWh only matters at the end of the year. If you still have net export kWh at true-up then the dollars don't matter any more because they wipe out your dollar credit balance and give you ~$0.03/kWh for your net export. However, you may still use up your credit and surplus kWh during the Nov-Feb months. Those are the worst for solar generation.

 

[RKCRLR]

Month by month your buckets are converted to dollars. The net kWh only matters at the end of the year. If you still have net export kWh at true-up then the dollars don't matter any more because they wipe out your dollar credit balance and give you ~$0.03/kWh for your net export. However, you may still use up your credit and surplus kWh during the Nov-Feb months. Those are the worst for solar generation.

I'm trying to wrap my head around what you are saying. Does that mean that if you are a net producer and they wipe out your dollar credit balance, your credit would be the same whether you used a lot during peak or nothing during peak if your total annual kWh usage was the same?

 

[wwhitney]

I'm trying to wrap my head around what you are saying. Does that mean that if you are a net producer and they wipe out your dollar credit balance, your credit would be the same whether you used a lot during peak or nothing during peak if your total annual kWh usage was the same?

Yes, that is true if you are a net energy exporter and have a dollar credit. It's conceivable to be a net energy exporter and have a dollar balance, then I believe you still have to pay. In other words, the annual energy cost goes like this:

For each bucket, convert it to dollars, positive or negative. Add them up.

If the sum is positive, you owe that amount.

If the sum is negative, a new computation is done. Just add up all the kWh exported/imported in each bucket. If that sum is a net export, you get the low reimbursement rate (~$0.03/kWh per miimura).

[One thing I'm unsure on is whether there are fixed monthly charges that can't be offset with a net dollar credit. I.e. whether the "if the sum is negative" check is done before or after adding some fixed monthly charges.]

Cheers,
Wayne

 

[getakey]

your B&W bill should show you what your up to date NEM balance is every month. It is the cumulative balance of adding the credits and debits. This should give you a way to predict where you will be at true up.

 

[RKCRLR]

Yes, that is true if you are a net energy exporter and have a dollar credit. It's conceivable to be a net energy exporter and have a dollar balance, then I believe you still have to pay. In other words, the annual energy cost goes like this:

For each bucket, convert it to dollars, positive or negative. Add them up.

If the sum is positive, you owe that amount.

If the sum is negative, a new computation is done. Just add up all the kWh exported/imported in each bucket. If that sum is a net export, you get the low reimbursement rate (~$0.03/kWh per miimura).

[One thing I'm unsure on is whether there are fixed monthly charges that can't be offset with a net dollar credit. I.e. whether the "if the sum is negative" check is done before or after adding some fixed monthly charges.]

Cheers,
Wayne

It just seems sort of strange that if you are a net producer you have no incentive to reduce your peak usage. Might as well use the dishwasher, washer, dryer, etc. whenever it is convenient. And instead of precooling your house to reduce consumption during peak you are better off just keeping a constant temperature.

And if you have Powerwalls you can keep them in 100% charged in backup mode with no financial impact.

Am I understanding this correctly?

 

[wwhitney]

I think so. I think PG&E wants to structure the economics to discourage net producers.

And like I said, if you stop paying attention at all and use a lot of Peak when the PV is not generating, you can be a net energy producer and still owe money.

Cheers, Wayne

 

[RKCRLR]

I think so. I think PG&E wants to structure the economics to discourage net producers.

And like I said, if you stop paying attention at all and use a lot of Peak when the PV is not generating, you can be a net energy producer and still owe money.

Cheers, Wayne

OK, I got it. There is still incentive to not use power during peak. For me, the objective is still to minimize minimize NBCs and Powerwall use by targeting the predicted annual cumulative dollar total of the bills to be $0. Effectively, this gives the same result as totaling the different buckets. You just don't get any additional compensation during True-Up if your surplus was during Peak.

It is interesting that it appears from the wording of the true-up bill that there isn't an incentive to reduce NBCs lower than your minimum delivery charges. If your NBCs were lower than your minimum delivery charges you would still wind up paying the total of the minimum delivery charges, is that correct?

 

[Ampster]

It is interesting that it appears from the wording of the true-up bill that there isn't an incentive to reduce NBCs lower than your minimum delivery charges. If your NBCs were lower than your minimum delivery charges you would still wind up paying the total of the minimum delivery charges, is that correct?

Good question and one that I am also unsure of as well. I have a vague recollection that @miimura explained it that way in another thread but can't find that explanation. At least that is what my strategy contemplates.

 

[miimura]

Good question and one that I am also unsure of as well. I have a vague recollection that @miimura explained it that way in another thread but can't find that explanation. At least that is what my strategy contemplates.

It is a good question. I'm not sure of the real answer about the interaction between NBCs and Minimums because I'm still on NEM 1 and don't pay NBCs.

There are also some small details about how the Minimum Charges are handled at true-up. For any month that your Energy Charges are positive and greater than the Minimum, your true-up balance will be reduced by that amount. It is less clear how lesser amounts are handled. I think if a month has a positive Energy Charge that is less than the Minimum, your true-up balance will be reduced by that positive amount. By the same logic, any month that has a negative Energy Charge will not cause any change to your true-up balance.

If you are a net kWh producer over the true-up period, the TOU is basically out the window unless you are a high peak user and the TOU is hurting you. It is theoretically possible to owe money even if you are a net exporter. If you have Powerwalls on TBC, you are unlikely to get into that situation because the Powerwalls are helping you avoid paying the Peak rate. As a net exporter, the only way to optimize your billable charges is to avoid NBCs. Self-Powered mode is probably the best way to do that.

 

[tfan2018]

Yes, that is true if you are a net energy exporter and have a dollar credit. It's conceivable to be a net energy exporter and have a dollar balance, then I believe you still have to pay. In other words, the annual energy cost goes like this:

For each bucket, convert it to dollars, positive or negative. Add them up.

If the sum is positive, you owe that amount.

If the sum is negative, a new computation is done. Just add up all the kWh exported/imported in each bucket. If that sum is a net export, you get the low reimbursement rate (~$0.03/kWh per miimura).

[One thing I'm unsure on is whether there are fixed monthly charges that can't be offset with a net dollar credit. I.e. whether the "if the sum is negative" check is done before or after adding some fixed monthly charges.]

Cheers,
Wayne

how does minimum bill factor into this (the $10 minimum monthly bill). plus, how are NBCs factored into the math above if sum is positive or negative?

 

[SaveOurPlanet]

Happy Halloween everyone! Last time I talked to the PG&E Solar Customer Service they told me that NBC is something you absolutely have to pay, no offset to anything regardless you are net producer or consumer, that's NEM2PS but I think NEM2 is the same, you are lucky if you have NEM. But he had to put me on hold twice to refer or confirm with someone or documents, so maybe he is wrong, but he works for PG&E.

 

[tfan2018]

Happy Halloween everyone! Last time I talked to the PG&E Solar Customer Service they told me that NBC is something you absolutely have to pay, no offset to anything regardless you are net producer or consumer, that's NEM2PS but I think NEM2 is the same, you are lucky if you have NEM. But he had to put me on hold twice to refer or confirm with someone or documents, so maybe he is wrong, but he works for PG&E.

Thanks, so it means it’s best to leverage PW and draw as little energy from grid as possible.

 

[sunwarriors]

It just seems sort of strange that if you are a net producer you have no incentive to reduce your peak usage. Might as well use the dishwasher, washer, dryer, etc. whenever it is convenient. And instead of precooling your house to reduce consumption during peak you are better off just keeping a constant temperature.

And if you have Powerwalls you can keep them in 100% charged in backup mode with no financial impact.

Am I understanding this correctly?

This was why a lot of utilities didn't want anyone to oversize their system much. Without batteries and on NEM2.0 ToU, they hope you use 2-3x more energy at the higher rates and sorta can't zero out your usage since no battery means no way to rate shift your use.

Also, once someone gets an EV without one in their initial install plan, assuming they have a decently long commute, you can probably bet that their system is now undersized with how much an EV can draw.

 

[miimura]

how does minimum bill factor into this (the $10 minimum monthly bill). plus, how are NBCs factored into the math above if sum is positive or negative?

You pay the Minimum Charges and Non-Bypassable Charges every month on your blue bill. The true-up is a separate transaction. PG&E does not pay out any credit balances from the true-up statement. If you are a net consumer of kWh over the year, your credit balance simply disappears. If you are a net exporter, the credit balance is replaced with the Net Surplus Compensation of ~$0.03/kWh. CCAs have their own rules about their Generation Charges and their credits for surplus exports and TOU credits. If you are on a CCA, you are not eligible for PG&E's Net Surplus Compensation. By the same token, if you are on a CCA, you will never get any credits paid out from PG&E at true-up.

 

[RKCRLR]

I'm a net producer. Below is a summary of my True-Up on EV2-A:

Total Energy Charges -$209.56
Total NEM charges before taxes: -$256.04
Total NBCs: $149.72
Total Minimum Delivery Charges: -$123.86
Total NEM Charges due: $25.86
Credit for Surplus (-841.562180kWh @$0.02576/kWh): -$21.68

The Total Energy Charges come from the sum of my monthly Energy Charges as stated on my monthly bills. The Total Minimum Delivery Charges come from the sum of what I paid what I paid on my monthly bills. The Total NEM Charges due is the difference between my Total NBCs and the Total Minimum Delivery Charges.