NEM-PS Annual True-Up Calculation [PG&E example]

[Redhill_qik]

Thanks! Do you still use allow the powerwall to discharge during on peak in the winter on E-TOU-C? The price differential is just 1-2 percentages more than the ~10% roundtrip efficiency.

I'm thinking of switching from EV2-A back to E-TOU-C as it looks like I am a net exporter either way, and I'm finding myself discharging my single powerwall more than expected in the winter due to my heat pump energy usage over 9 hours.

I have my Powerwall reserve set to 95% for the winter with a Peak start the of 6:30pm (after sunset). I think giving it a little exercise once a day is good for the health of the system without losing too much due to the inefficiency.

I'm also pretty high in the Summer, I think I was doing 85% last summer again with an earlier start of 4:00pm. That gives a higher differential to the baseline hours for the event which were skewed later in the Peak period for increased VPP compensation.

When you are a net producer/exporter the incentive picture is very different than a net consumer/importer.

 

[sorka]

Are you referring to the PG&E black and white bill that is 10+ pages long? If so, that is sent to accounts with that.have ESS/Powerwalls and are on NEM-PS or NEM-MT.

There is an online version of this, but you have to get to it through multiple clicks using the Account pulldown at the top and selecting My Accounts & Services. Then you select the NEM electric account (it isn't obvious which one this this, so try until you find it then add a nickname for the future) and then finally you week get another pulldown selector for the monthly statements.

Once you are comfortable finding this you can call the PG&E solar customer service line and have them stop sending you the paper statement.

They REALLY don't want you to look at the B&W bill.

 

[Redhill_qik]

They REALLY don't want you to look at the B&W bill.

Personally I think that Hanlon's razor applies "Never attribute to malice that which is adequately explained by stupidity" to which in the case of large corporations I would add the corollary "or by the least amount effort". PG&E appears to have just repurposed their software for large generation facilities for residential ESS and it is roughly that #1 grit sand paper.

 

[FurryOne]

For anyone in NYState under National Grid, the whole process is a lot simpler. If you have VTOU service, the day is split into two rate periods most of the year - On Peak: 7am-11pm, and Off Peak: 11pm-7am. During June-September a third rate period is added - Super Peak: 2pm-7pm. Power credits generated during these three rate periods can't be mixed, so even if you have On Peak credit, it can't be used to offset electrical usage during Off Peak times, and vice-versa. Where a problem comes in is if your Anniversary month is, say, March, and you end September with Super Peak credits, all they can do is sit there until your anniversary (or until June's Super Peak rate period starts again.) With National Grid you only have two options for your Anniversary - True-up on your Anniversary (#3 if your Month is March), or No True-up (#0 which will roll-over your electrical credits in each rate period continuously, forever.) Most people start with a yearly True-up. National Grid allows a change ONLY ONCE, so if you switch, there's no going back. If you stay with the yearly True-up, National Grid combines all electrical credit on your anniversary date (from all the rate periods) and credits your account an amount of $$ based on the wholesale On Peak rate that day. (I got roughly 5 cents/kWh for 2,000kWhs even though I'd generated almost half that during Super Peak times where the wholesale rates were 10 cents & higher) Remember that this is under VTOU Service only. I'm not sure exactly how this works if you're running solar on their SC1 standard Residential Service.

 

[YRide]

Thanks @swedge fir the reminder to this. I had read before (and “liked” the excellent work by the team who created this)…

I’m still struggling to fully internalize the math on whether NBC’s are going to hammer me or not being a net-importer (of actual kWh’s, or really MWh’s!) but being a 10.8kW system with 4x PW, 3x EV and an EV2A tariff with Grid Charging, Export Everything and now Charge on Solar.

Behaviorally, my biggest issue is the PW’s seem to fill up to 100% every night. They don’t partially fill, and allow Solar to top them up to 100% SoC the next day before 4p peak (or 3p part-peak). If they anticipated a reasonable amount of Solar charge by 3p (say 30kWh) that would be 30kWh daily x 365 = 11MWh or like $350 NBC’s.

I still don’t have my first B&W bill…PTO was late June. So I suspect that is another 1-2mo away from now?

Once I get that I’ll use the guide here and run a pre-empty live calc. That will maybe help me understand if I should be bothering with GC and/or EE…but I suspect again as I am a net importer (of power), they can basically help me become a net generator (of $).

It is impressive the complexity of this. They could just use this in lieu of SAT’s. Or maybe a Fields Medal?

 

[miimura]

I don't see a good reason to use Grid Charging during good solar generation months. As long as you can recharge your Powerwalls enough from solar before 3pm to make it through without drawing from the grid from 3pm to midnight (Part-Peak and Peak periods), that is sufficient. Any extra grid charging of the batteries is just going to result in more potential NBCs and exporting solar energy during Off-Peak.

Personally, I would only consider using Grid Charging during periods that cannot fill the Powerwalls and it results in paying for grid usage during Peak or Part-Peak periods. I have calculated how much extra I have paid for Winter Part-Peak and Peak usage (annual total) and it has varied between $160 and $200 for the last 3 years that I have tracked it. I suspect that after my solar array is increased from 4.3kW to 10.3kW the yellow zones below will shrink dramatically.

 

[h2ofun]

I don't see a good reason to use Grid Charging during good solar generation months. As long as you can recharge your Powerwalls enough from solar before 3pm to make it through without drawing from the grid from 3pm to midnight (Part-Peak and Peak periods), that is sufficient. Any extra grid charging of the batteries is just going to result in more potential NBCs and exporting solar energy during Off-Peak.

Personally, I would only consider using Grid Charging during periods that cannot fill the Powerwalls and it results in paying for grid usage during Peak or Part-Peak periods. I have calculated how much extra I have paid for Winter Part-Peak and Peak usage (annual total) and it has varied between $160 and $200 for the last 3 years that I have tracked it. I suspect that after my solar array is increased from 4.3kW to 10.3kW the yellow zones below will shrink dramatically.

View attachment 964396

I only consider grid charging during winter where my heat pumps use way more than I can produce with solar

 

[swedge]

Thanks @swedge fir the reminder to this. I had read before (and “liked” the excellent work by the team who created this)…

I’m still struggling to fully internalize the math on whether NBC’s are going to hammer me or not being a net-importer (of actual kWh’s, or really MWh’s!) but being a 10.8kW system with 4x PW, 3x EV and an EV2A tariff with Grid Charging, Export Everything and now Charge on Solar.

Behaviorally, my biggest issue is the PW’s seem to fill up to 100% every night. They don’t partially fill, and allow Solar to top them up to 100% SoC the next day before 4p peak (or 3p part-peak). If they anticipated a reasonable amount of Solar charge by 3p (say 30kWh) that would be 30kWh daily x 365 = 11MWh or like $350 NBC’s.

I still don’t have my first B&W bill…PTO was late June. So I suspect that is another 1-2mo away from now?

Once I get that I’ll use the guide here and run a pre-empty live calc. That will maybe help me understand if I should be bothering with GC and/or EE…but I suspect again as I am a net importer (of power), they can basically help me become a net generator (of $).

It is impressive the complexity of this. They could just use this in lieu of SAT’s. Or maybe a Fields Medal?

You can download a .pdf of the B&W usually as soon as your blue bill goes out. PG&E hides it as follows:

• Log in to your PGE.com account.
• Click on HI, you, and My Accounts & Services on the pop up.
• Click on the Electric Service ID
• Look for Download Detail of Bill
• Drop down list and select the appropriate month.

They post those there in a fairly timely manner because they need the number from that to issue your standard blue bill. I'm not sure about timing after PTO, but I see no plausible excuse for delay.

Don't worry too much about the true-up math. I figure both EE and GC together decrease my true-up by around $200, not a big deal compared to what solar and PW do for you already. Fine tuning may tweak that a bit, but you don't need to sweat the small stuff too much.

I suspect your PW may be grid charging because it anticipation of your car charging. To ferret this out, you might try turning off export everything and not charging you EVs for a few days.

My system does not do this, but it is configured differently, with the car charger outside of and not monitored by the gateway. I have my single PW set to 20% backup, and the house uses about 50% during peak and partial peak, leaving 30% or more to export if export everything is enabled. This is why I'm guessing your car charging is confusing yours.

As for being a net generator of $, that will not happen if you are a net importer of kWh. The best you can do is a zero true up, meaning you paid only the $11 per month all year. This is because the credits from export are forfeited if they say PG&E owe you money. And zero happens only if your NBC's total less than the ~$11 X 12 months = $131. That means that if you draw 4,000 kWh or more of imports, no mater how much you export, you'll still owe some at true-up.

 

[YRide]

I don't see a good reason to use Grid Charging during good solar generation months. As long as you can recharge your Powerwalls enough from solar before 3pm to make it through without drawing from the grid from 3pm to midnight (Part-Peak and Peak periods), that is sufficient. Any extra grid charging of the batteries is just going to result in more potential NBCs and exporting solar energy during Off-Peak.

Personally, I would only consider using Grid Charging during periods that cannot fill the Powerwalls and it results in paying for grid usage during Peak or Part-Peak periods. I have calculated how much extra I have paid for Winter Part-Peak and Peak usage (annual total) and it has varied between $160 and $200 for the last 3 years that I have tracked it. I suspect that after my solar array is increased from 4.3kW to 10.3kW the yellow zones below will shrink dramatically.

View attachment 964396

I have just enough to fully charge the PW’s (4x) on a full day cycle, but that’s by like 730p in summer, not 3p (or 4p). By grid charging (right now PW algorithm goes to 100% SoC off-peak, usually by 3a) I have to find a home for PV during the day…combo of CoS (for 2x EV’s with latest FW) and ChsrgeHQ excess PV tracking (for the third EV that doesn’t have latest FW). Then at 3p I can dump residual solar to grid at part-peak and then leak sell back rates. And at 4p the PW’s dump 95% of their 54kWh straight to the grid at peak. The thinking being this will bank me significant NEM $ credits for winter. With 3x EV, and only 10.8kW PV system, I am a nom-minor net consumer (of kWh).

You said…

Any extra grid charging of the batteries is just going to result in more potential NBCs and exporting solar energy during Off-Peak.

But I should be able to dump GC power back on at peak, not off-peak rates. I pay NBC, but that’s like 3c/kWh, and the TOU arbitrage delta is like 31c/kWh minus 10% minus NBC, so still like 24-24c/kWh if I’m doing my math right.

 

[YRide]

You can download a .pdf of the B&W usually as soon as your blue bill goes out. PG&E hides it as follows:

• Log in to your PGE.com account.
• Click on HI, you, and My Accounts & Services on the pop up.
• Click on the Electric Service ID
• Look for Download Detail of Bill
• Drop down list and select the appropriate month.

They post those there in a fairly timely manner because they need the number from that to issue your standard blue bill. I'm not sure about timing after PTO, but I see no plausible excuse for delay.

Don't worry too much about the true-up math. I figure both EE and GC together decrease my true-up by around $200, not a big deal compared to what solar and PW do for you already. Fine tuning may tweak that a bit, but you don't need to sweat the small stuff too much.

I suspect your PW may be grid charging because it anticipation of your car charging. To ferret this out, you might try turning off export everything and not charging you EVs for a few days.

My system does not do this, but it is configured differently, with the car charger outside of and not monitored by the gateway. I have my single PW set to 20% backup, and the house uses about 50% during peak and partial peak, leaving 30% or more to export if export everything is enabled. This is why I'm guessing your car charging is confusing yours.

As for being a net generator of $, that will not happen if you are a net importer of kWh. The best you can do is a zero true up, meaning you paid only the $11 per month all year. This is because the credits from export are forfeited if they say PG&E owe you money. And zero happens only if your NBC's total less than the ~$11 X 12 months = $131. That means that if you draw 4,000 kWh or more of imports, no mater how much you export, you'll still owe some at true-up.

I’ve followed the original post, your post just now, other instructions for the B&W…but I just can’t see it. I see the three service ID’s, one is gas, one seems to be blank and other seems to be precursor to
NEM2PS…but there’s no detail once selected. Thought I read multiple places this can take, 2, 3, 4+of the where they back date a re-report your bill?

 

[YRide]

As for being a net generator of $, that will not happen if you are a net importer of kWh. The best you can do is a zero true up, meaning you paid only the $11 per month all year. This is because the credits from export are forfeited if they say PG&E owe you money. And zero happens only if your NBC's total less than the ~$11 X 12 months = $131. That means that if you draw 4,000 kWh or more of imports, no mater how much you export, you'll still owe some at true-up.

Sorry, yes, this is what I meant. As an overall net consumer of kWh on an annual basis (3x EV vs only 10.8kW PV)…I’m thinking I can substantially equalize that kWH imbalance toward $ parity leveraging NEM2 benefits from time shifting my PV + using grid charging to cover my usage deficit during peak and part-peak. Basically I should have the full usage of the 4x PW’s (well, 95% of them, 51.3kWh) to generate peak credits, while ensuring I take no peak or part-peak imports. So I require GC to offset house & EV loads during those two windows (technically I shouldn’t have EV loads then). Ideally, PW would only GC just enough to allow PV during the day to get it to 100% SoC, but it’s going all the way with GC in early AM, so I’m accruing more NBC then I want at the moment.

 

[Redhill_qik]

I’ve followed the original post, your post just now, other instructions for the B&W…but I just can’t see it. I see the three service ID’s, one is gas, one seems to be blank and other seems to be precursor to
NEM2PS…but there’s no detail once selected. Thought I read multiple places this can take, 2, 3, 4+of the where they back date a re-report your bill?

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Did you click into the all of the links? One will be the B&W NEM2PS billing account. Here is what the Accounts and Services page looks like for me.

I don't recall what the default nicknames were before I changed them. When you click on the right account, the Service Details page should look like this:

And the pulldown at the bottom let's you select the B&W billing monthly to download.

 

[YRide]

Did you click into the all of the links? One will be the B&W NEM2PS billing account. Here is what the Accounts and Services page looks like for me.

View attachment 964859

I don't recall what the default nicknames were before I changed them. When you click on the right account, the Service Details page should look like this:
View attachment 964860

And the pulldown at the bottom let's you select the B&W billing monthly to download.

Yep, was able to click through all three...one is clearly my residential gas, one is unknown and one is an eletric rate "H2EV2AN". I noted that none of the two non-gas ones show NEM2PS, so i'm thinking stuff just hasnt processed rate. Both the non-gas service ID's have dates the day before my PTO.

@Redhill_qik does is 11/1/20 the date of your PTO?

Since my PTO was late June, i'm just assuming it's still in the transfer phase. Didnt most people indicated this can take 2-3, or sometimes 4 (with all the NEM2 push) months?

 

[Redhill_qik]

Yep, was able to click through all three...one is clearly my residential gas, one is unknown and one is an eletric rate "H2EV2AN". I noted that none of the two non-gas ones show NEM2PS, so i'm thinking stuff just hasnt processed rate. Both the non-gas service ID's have dates the day before my PTO.

@Redhill_qik does is 11/1/20 the date of your PTO?

Since my PTO was late June, i'm just assuming it's still in the transfer phase. Didnt most people indicated this can take 2-3, or sometimes 4 (with all the NEM2 push) months?

Yes, my PTO was on 11/1/2020 which matches the Status field . And yes, it can take 2-3 months for the conversion to happen and the retroactive PG&E bill is quite a mess of numbers. My billing cycle ends between the 23-27th and NEM2PS entries first showed up on my bill ending on 12/23/2020 with a statement date of 01/05/2021, so 2 months for me.

 

[holeydonut]

Yep, was able to click through all three...one is clearly my residential gas, one is unknown and one is an eletric rate "H2EV2AN". I noted that none of the two non-gas ones show NEM2PS, so i'm thinking stuff just hasnt processed rate. Both the non-gas service ID's have dates the day before my PTO.

@Redhill_qik does is 11/1/20 the date of your PTO?

Since my PTO was late June, i'm just assuming it's still in the transfer phase. Didnt most people indicated this can take 2-3, or sometimes 4 (with all the NEM2 push) months?

BTW you're not the only one that has this glitch. When I log in, I also see this H2EV2AN thing, and there is no "download detail of bill" option under the outage block. I used to have a drop-down there to get the black and white bill, but that vanished a few months ago.

I even stopped getting the black and white bill in the mail.

But, now I have a cool series of graphs on my 'normal blue header' PG&E bills.

 

[swedge]

BTW you're not the only one that has this glitch. When I log in, I also see this H2EV2AN thing, and there is no "download detail of bill" option under the outage block. I used to have a drop-down there to get the black and white bill, but that vanished a few months ago.

I even stopped getting the black and white bill in the mail.

But, now I have a cool series of graphs on my 'normal blue header' PG&E bills.
View attachment 965557
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It looks like they forgot you have a PowerWall. But how else can they explain all those peak period exports?

I see that called it NEM Charges and NEM Balance, while my NEM2 bills call this Energy Charges or Credits. I gather you are still on NEM1?

 

[holeydonut]

It looks like they forgot you have a PowerWall. But how else can they explain all those peak period exports?

I see that called it NEM Charges and NEM Balance, while my NEM2 bills call this Energy Charges or Credits. I gather you are still on NEM1?

I'm definitely on NEM 2.0... at least I should be hahaha. I guess you're right, maybe somehow they think I'm on a solar only NEM without the paired storage?

I don't actually know how I have so much peak time export on that particular bill. That graph was before the latest round of VPP participation, so the only peak-time export I should have had was any contemporaneous solar generation that was sent to the grid after 4pm. And it does seem kind of high.

On my next bill, I expect some wicked high peak exports. This Sunrun VPP exports about 20 kWh from my batteries to the grid from 7pm to 9pm every day... and I literally cannot turn it off. If I set my reserve to 100% it changes back to 33% anyway hahaha.

What sucks is that NEM credits have no cash-out value. The only thing with value is the kWh differential of what was exported vs imported. So I think next March I'm going to have to let a bunch of people charge EVs at my house. NACS and J1772 it don't matter!

 

[swedge]

I'm definitely on NEM 2.0... at least I should be hahaha. I guess you're right, maybe somehow they think I'm on a solar only NEM without the paired storage?

I don't actually know how I have so much peak time export on that particular bill. That graph was before the latest round of VPP participation, so the only peak-time export I should have had was any contemporaneous solar generation that was sent to the grid after 4pm. And it does seem kind of high.

On my next bill, I expect some wicked high peak exports. This Sunrun VPP exports about 20 kWh from my batteries to the grid from 7pm to 9pm every day... and I literally cannot turn it off. If I set my reserve to 100% it changes back to 33% anyway hahaha.

What sucks is that NEM credits have no cash-out value. The only thing with value is the kWh differential of what was exported vs imported. So I think next March I'm going to have to let a bunch of people charge EVs at my house. NACS and J1772 it don't matter!

Maybe it is not your bill at all. Did you check the name and address? Kidding, of course.

When Telsa couldn't figure out why my car thought the trunk was flapping open, and accidentally bricked the car so it could not open doors or the frunk, and then couldn't get parts, the only explanation was "Tesla".

With your bill, my weird true-up (they under charged me), rapidly rising prices, and NEM3, all I can say is "PG&E".

In truth, I think the grid is amazing. We get light, heat, A/C, EV go-juice, TV, internet, street lights, stoplights, radar, computers, modernity, etc, etc, etc, all powered by those thin overhead and underground wires. 60.0 Hz 240V, 24/7 (mostly) come rain or shine. Amazing. But still, what do you get when you add F to a "utility" ? "Futility".

 

[YRide]

BTW you're not the only one that has this glitch. When I log in, I also see this H2EV2AN thing, and there is no "download detail of bill" option under the outage block. I used to have a drop-down there to get the black and white bill, but that vanished a few months ago.

I even stopped getting the black and white bill in the mail.

But, now I have a cool series of graphs on my 'normal blue header' PG&E bills.
View attachment 965557
View attachment 965559

@holeydonut when was your PTO? Recent? It sounds like it was a while ago?

My PTO was end June. My understanding is not having B&W isn’t a glitch, it just takes 2-3+ months for PGE to reissue it. Or is this a new approach to billing?

I just got my 2nd blue header bill since PTO, but my first full month since PTO (previous bill was partial EV2A+ Solar with no export and then some PTO). This bill has all these new tables…

And yeah, definitely shows me on EV2A + NEM2.

@swedge does it look like I can use this instead of B&W to predict my EOY true up? It seems like I’m going to be a significant net consumer of kWh (mainly off peak as well as overall) but that my peak export credits will largely balance out on the $ perspective. So it looks like it’s gonna be mainly NBC’s.

I still can’t tell what my peak monthly allowable exports are. Need to make sure I don’t exceed that.

 

[swedge]

@holeydonut when was your PTO? Recent? It sounds like it was a while ago?

My PTO was end June. My understanding is not having B&W isn’t a glitch, it just takes 2-3+ months for PGE to reissue it. Or is this a new approach to billing?

I just got my 2nd blue header bill since PTO, but my first full month since PTO (previous bill was partial EV2A+ Solar with no export and then some PTO). This bill has all these new tables…

And yeah, definitely shows me on EV2A + NEM2.

@swedge does it look like I can use this instead of B&W to predict my EOY true up? It seems like I’m going to be a significant net consumer of kWh (mainly off peak as well as overall) but that my peak export credits will largely balance out on the $ perspective. So it looks like it’s gonna be mainly NBC’s.

I still can’t tell what my peak monthly allowable exports are. Need to make sure I don’t exceed that.

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I had not seen this version of a bill before, thanks for publishing it. This looks like a solar only NEM2 bill. I think the only factor added by storage is the limitation of NEM credits only to the amount of estimated solar production. The estimate is based on theoretical production for your system, based on panel count, orientation, inverter efficiency and sun position for each month. I'm not sure what it does about weather, but in my experience the estimate is far above actual exports. This is due to a substantial amount of our solar being consumed rather than exported. If and when they get you the detailed bill, the export credit probably will not be a problem. In addition to that, the detailed bill will show how your payments get accounted for across the various bundled rate categories, but this is only for their internal account. Hence the 16 pages...

Durning summer months with high solar production, NBC's dominate because the NEM charges are small or negative. But durning winter, your NEM charges will probably be positive, and considerably larger than the NBCs, so your turn-up will probably be based on NEM rather than NBCs. In either case, the monthly minimums will have already been paid, so that amount will be subtracted from the NEM or NBC basis to arrive at the true-up adjustment which you will owe on that true-up bill.