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New Powerwall Advanced Options [Toggles for charging from and discharging to grid from powerwalls]

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So these are included in the normal rates, but are not credited for exports under NEM2. I think of it as a tax on exports. In effect our sell price is 2.449 cents less that our buy price. Relative to the $0.2448 off peak price, this is a 10% tax. Not huge, but not trivial.
It's somewhat worse than that, because of the non-bypassable part.

I.e. say there are two TOU rates, $0.25/kWh off peak and $0.30/kWh peak, and NBCs are $0.03/kWh in each case. And say during peak you import 0 kWh and export 100 kWh, while during off peak you import 100 kWhs and export 0 kWhs.

Then you might think your bill is $0, because the peak credit would be $27, and the off peak charge is $25. But in fact the bill is $3, because you can't offset the NBCs from the imported energy with the credits from the exported energy.

Cheers, Wayne
 
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I think of it as a tax on re-importing the energy you already have been credited for. You don't pay NBCs on exported energy that you don't re-import. And you don't pay NBCs on energy you use once you have exhausted your credit.


I think this is the confusing part… wwhitney thinks you pay NBC on all imports and I think NBC is capped at your export credit kWh.

Why the hell are these things so complicated lol.

The only thing I think we can all agree with is Solar + ESS = awesome.
 
Well thanks to you all I think I now have a fairly reasonable way to inform the Tesla app of the costs of NBCs and where they apply. So I will back off the NBC value from the export price in my rate tables.

Probably won't make a big difference but it could affect the operation in fringe cases and I'll feel better. 🙂
 
I think this is the confusing part… wwhitney thinks you pay NBC on all imports and I think NBC is capped at your export credit kWh.

Why the hell are these things so complicated lol.

The only thing I think we can all agree with is Solar + ESS = awesome.
The NBC is mostly an accounting mechanism to make sure that four line items are always paid for the kWh that you import. The four line items are Public Purpose Programs ($0.01954), Nuclear Decomissioning (-$0.00013 yes this is a credit right now), Competition Transition Charge ($0.00023) and Wildfire Fund ($0.00141) and these add up to $0.02423/kWh.

On the monthly bill this is presented as imported kWh * $0.02423. On the NEMPS/NEMMT black bill if you are with a CCA then it is also shown as a PG&E sub-total with PPP+ND and a CCA sub-total with CTC+WF. However, these monthly number aren't final. If you are a net consumer then at true-up it will be reduced to just the non-paid imports, so if you had imported 2,500 kWh and exported 1,900 kWh then you pay only NBCs on the difference (2500-1900 = 600 kWh * NBC) in addition to your NEM charge totals. If you are a net producer and exported more than you imported then the NBC total is the total for the year.

In both cases, your annual total of Minimum Daily Charges that you have already paid is subtracted from your NEM+net NBC or NBC total and that is what you owe. BTW, the MDC is total of all of the various tariff components which include the four that make up the NBC. The current MDC is $0.34810/day which is worth 14.07 kWh of NBCs per day, so if you are a net producer you can import 5,135 kWh over the year and owe nothing at true-up as it matches the amount of MDCs that you have already paid.
 
The NBC is mostly an accounting mechanism to make sure that four line items are always paid for the kWh that you import. The four line items are Public Purpose Programs ($0.01954), Nuclear Decomissioning (-$0.00013 yes this is a credit right now), Competition Transition Charge ($0.00023) and Wildfire Fund ($0.00141) and these add up to $0.02423/kWh.

On the monthly bill this is presented as imported kWh * $0.02423. On the NEMPS/NEMMT black bill if you are with a CCA then it is also shown as a PG&E sub-total with PPP+ND and a CCA sub-total with CTC+WF. However, these monthly number aren't final. If you are a net consumer then at true-up it will be reduced to just the non-paid imports, so if you had imported 2,500 kWh and exported 1,900 kWh then you pay only NBCs on the difference (2500-1900 = 600 kWh * NBC) in addition to your NEM charge totals. If you are a net producer and exported more than you imported then the NBC total is the total for the year.

In both cases, your annual total of Minimum Daily Charges that you have already paid is subtracted from your NEM+net NBC or NBC total and that is what you owe. BTW, the MDC is total of all of the various tariff components which include the four that make up the NBC. The current MDC is $0.34810/day which is worth 14.07 kWh of NBCs per day, so if you are a net producer you can import 5,135 kWh over the year and owe nothing at true-up as it matches the amount of MDCs that you have already paid.


Ok so in wwhitney's earlier example, he assumed $0.30 per kWh as the "retail rate" and the NBC was $0.03 per kWh.

I think we all agree that if a homeowner imports 100 kWh (per year) and exports 100 kWh (per year), they are exactly NEM-neutral, and the
NBC = 100 kWh imported x $0.03 = $3.00

But for the other example where a homeowner imports 100 kWh (per year) and exports 50 kWh (per year)... what would be their bill?

Is it...
(50 kWh net imported at retail $0.30/kWh) + (100 kWh imported x $0.03 NBC) = ($15.00) + ($3.00) = $18.00?

Or is the NBC capped at the exported kWh?...
(50 kWh net imported at retail $0.30/kWh) + (50 kWh capped kWh x $0.03 NBC) = ($15.00) + ($1.50) = $16.50?
 
Ok so in wwhitney's earlier example, he assumed $0.30 per kWh as the "retail rate" and the NBC was $0.03 per kWh.

I think we all agree that if a homeowner imports 100 kWh (per year) and exports 100 kWh (per year), they are exactly NEM-neutral, and the
NBC = 100 kWh imported x $0.03 = $3.00

But for the other example where a homeowner imports 100 kWh (per year) and exports 50 kWh (per year)... what would be their bill?

Is it...
(50 kWh net imported at retail $0.30/kWh) + (100 kWh imported x $0.03 NBC) = ($15.00) + ($3.00) = $18.00?

Or is the NBC capped at the exported kWh?...
(50 kWh net imported at retail $0.30/kWh) + (50 kWh capped kWh x $0.03 NBC) = ($15.00) + ($1.50) = $16.50?
NBC's are just a part of the retail rate, that can't be avoided. If the retail rate is $0.30, the $0.03 that can't be bypassed is already in there.

Since you have the 100 in, 100 out scenario clear, you also know 50 in, 50 out. Then just consume another 50 in, at retail, like every non-NEM customer, to drive at the 2nd scenario; retail is retail, imported by definition.
 
NBC's are just a part of the retail rate, that can't be avoided. If the retail rate is $0.30, the $0.03 that can't be bypassed is already in there.

Since you have the 100 in, 100 out scenario clear, you also know 50 in, 50 out. Then just consume another 50 in, at retail, like every non-NEM customer, to drive at the 2nd scenario; retail is retail, imported by definition.


You lost me on the 50 in 50 out thing...

So in the example above with imports of 100 kWh and solar exports of 50 kWh is the homeowner's annual costs $18.00 or $16.50 or something else alltogether?
 
However, these monthly number aren't final. If you are a net consumer then at true-up it will be reduced to just the non-paid imports, so if you had imported 2,500 kWh and exported 1,900 kWh then you pay only NBCs on the difference (2500-1900 = 600 kWh * NBC) in addition to your NEM charge totals. If you are a net producer and exported more than you imported then the NBC total is the total for the year.
You lost me here. Let's go back to my example with just one TOU bucket, no minimum daily charges, and a $0.33 retail rate of which $0.03 are NBCs.

Non-NEM customer uses 100 kWh: bill is $33
NEM customer imports 100 kWh, no export: bill is $33
NEM customer imports 100 kWh, exports 100 kWh: bill is $0 or $3?

I have always assumed that the bill is $3. Otherwise, how is NEM2 different from NEM1 (which has no NBCs and for which the bill would be $0)? That conflicts with your statement that you "only pay NBCs on the difference."

Cheers, Wayne
 
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You lost me here. Let's go back to my example with just one TOU bucket, no minimum daily charges, and a $0.33 retail rate of which $0.03 are NBCs.

Non-NEM customer uses 100 kWh: bill is $33
NEM customer imports 100 kWh, no export: bill is $33
NEM customer imports 100 kWh, exports 100 kWh: bill is $0 or $3?

I have always assumed that the bill is $3. Otherwise, how is NEM2 different from NEM1 (which has no NBCs and for which the bill would be $0)? That conflicts with your statement that you "only pay NBCs on the difference."

Cheers, Wayne


For the 100 kWh imported and 50 kWh exported example you drew up ... I hope redhill_qik and wwu123 say $16.50 instead of $18.00 hehe.

Edit: I hate how complicated electricity bills are...
 
Ok so in wwhitney's earlier example, he assumed $0.30 per kWh as the "retail rate" and the NBC was $0.03 per kWh.
No, I assumed that $0.33/kWh was the retail rate, of which the NBCs make up $0.03/kWh.

You lost me on the 50 in 50 out thing...
The point was that if you express your usage as (imports, exports), then you know (X,0) gives a bill of $0.30 * X [in your example, as you used a different retail rate than me.] And you know that (Y,Y) gives a bill of $0.03 (NBCs) * Y. So if the billing is linear, then (X+Y, Y) gives a bill of $0.30 * X + $0.03 * Y.

In other words,, the answer to your example would be $16.50 using your example rates.

Cheers, Wayne
 
You lost me here. Let's go back to my example with just one TOU bucket, no minimum daily charges, and a $0.33 retail rate of which $0.03 are NBCs.

Non-NEM customer uses 100 kWh: bill is $33
NEM customer imports 100 kWh, no export: bill is $33
NEM customer imports 100 kWh, exports 100 kWh: bill is $0 or $3?

I have always assumed that the bill is $3. Otherwise, how is NEM2 different from NEM1 (which has no NBCs and for which the bill would be $0)? That conflicts with your statement that you "only pay NBCs on the difference."

Cheers, Wayne
Oh, this is the key question. I haven't done any deep reading but Ive understood the second NEM case to be $3. I can't seen it working any other way that doesn't make it the same as NEM1.
 
The four line items are Public Purpose Programs ($0.01954), Nuclear Decomissioning (-$0.00013 yes this is a credit right now), Competition Transition Charge ($0.00023) and Wildfire Fund ($0.00141)
I am good with the PPP and ND items on my White Bill (non CCA) but the CTC and WF line items don't seem correct.

The $0.00023 >>> OCF code and the $0.00141 >>> WH.

Can you confirm these are the correct codes?
 
Ok so in wwhitney's earlier example, he assumed $0.30 per kWh as the "retail rate" and the NBC was $0.03 per kWh.

I think we all agree that if a homeowner imports 100 kWh (per year) and exports 100 kWh (per year), they are exactly NEM-neutral, and the
NBC = 100 kWh imported x $0.03 = $3.00

But for the other example where a homeowner imports 100 kWh (per year) and exports 50 kWh (per year)... what would be their bill?

Is it...
(50 kWh net imported at retail $0.30/kWh) + (100 kWh imported x $0.03 NBC) = ($15.00) + ($3.00) = $18.00?

Or is the NBC capped at the exported kWh?...
(50 kWh net imported at retail $0.30/kWh) + (50 kWh capped kWh x $0.03 NBC) = ($15.00) + ($1.50) = $16.50?
Your example is confusing as the numbers are symmetrical. Let's change it to importing 10,000 kWh and exporting 7,500 kWh. You pay the retail NEM charges on the 2,500 kWh difference and 7,500 kWh * NBC rate minus the annual MDC that you have already paid.
 
You lost me here. Let's go back to my example with just one TOU bucket, no minimum daily charges, and a $0.33 retail rate of which $0.03 are NBCs.

Non-NEM customer uses 100 kWh: bill is $33
NEM customer imports 100 kWh, no export: bill is $33
NEM customer imports 100 kWh, exports 100 kWh: bill is $0 or $3?

I have always assumed that the bill is $3. Otherwise, how is NEM2 different from NEM1 (which has no NBCs and for which the bill would be $0)? That conflicts with your statement that you "only pay NBCs on the difference."

Cheers, Wayne
In your net zero edge case scenario you would owe the $3.00 because you paid no NBCs on your imports as your NEM charges were $0.00.
 
Your example is confusing as the numbers are symmetrical. Let's change it to importing 10,000 kWh and exporting 7,500 kWh. You pay the retail NEM charges on the 2,500 kWh difference and 7,500 kWh * NBC rate minus the annual MDC that you have already paid.

Ok I was using a 100 import vs 50 export ... but your example works too. So yeah, let's now use your example...

The semantics of this whole thing has been what is mixing me up... I think the phrase "paying the NBC" is where I'm getting mixed up. But I think swedge, myself, wwhitney, you, and miimura are all saying the same thing.

I still think it's easiest to just conceptualize the NBC as a reduction of export credit. That is why for the sake of the Tesla App, it's better to just go into the "utility pricing" and reduce the value of the exported energy by $0.03 compared to the imported energy rate.

The NBC is always "going to be paid" ... but to your point it's basically an item where the homeowner isn't getting export credit for the NBC because they'll either "pay it" on the re-import of the NEM energy; or "lose the value" when they get the wholesale rate for over-producing kWh on the NEM true-up.

But PG&E doesn't bill this way. They simply calculate a NBC as the unavoidable cost for (in your example) having sent 7,500 kWh to their grid and taken 7,500 kWh from their grid.
 
In your net zero edge case scenario you would owe the $3.00 because you paid no NBCs on your imports as your NEM charges were $0.00.
I think we are in agreement now. The phrase "only pay NBCs on the difference" threw me, because NBCs are part of the retail rate, so you pay NBCs on everything.

But you could say that when imports > exports, you pay full retail rate on "net imports" (imports - exports) and then "only the NBCs) on the "exports".

Cheers, Wayne
 
Yes, that covers most cases. But it's actually a bit worse than that, as per my post #582: New Powerwall Advanced Options [Toggle for charging from the grid that is not stormwatch mode!]

Cheers, Wayne


Yeahhhhhhh, I'm agreeing with myself to ignore that post you just linked since that's the post that screwed me up to begin with hah.

PS, those threads in the main Tesla forums show other people are thinking about this too! NBCs and NEM 3.0 are getting people to think about how to use the grid as little as possible...

 
Yeahhhhhhh, I'm agreeing with myself to ignore that post you just linked since that's the post that screwed me up to begin with hah.
At the risk of confusing you again, let me try putting it this way:

The retail rates on a TOU plan are what non-NEM customers pay. If you are NEM2, some fraction of those rates are the NBCs. So you could say "retail rate = NBCs + refundable charges" for each TOU bucket (off peak, part peak, peak).

Then if you aren't a net exporter of energy, your bill is:

(a) at least the NBCs for all imported energy (ignoring exports)
(b) plus the net "refundable charges" for your TOU net energy use across all buckets, if that's positive (if it's a credit, you lose it)
(c) and then rounded up to the minimum charge, if the bill is still below the minimum charge.

Of course, the bill is monthly, while the true-up is annual, so (b) and I think hence (c) can only be finalized at true-up.

Cheers, Wayne
 
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