Interaction of PG&E NEM-2 and EV2-A

[graubart]

Does anyone know of a good explanation of how PG&E's NEM-2 for solar panels interacts with the EV2-A rate plan? Sample scenario:
I generate 5 MWh during the year from solar panels.
Not counting my Tesla, I consume 5 MWh during the year, all at peak hours when rate is $0.56/kWh
Charging my Tesla, I consume another 5MWh during the year, all off-peak when rate is $0.25/kWh
No Power Walls or other storage.

Does NEM-2 only look at totals: 10 MWh used and 5 MWh generated, so I owe for the other 5 MWh at some rate such that it didn't matter that I charged the Tesla only off-peak?
I thought an answer would be easy to find, but no luck so far.
My first post, so apologies if this has been asked and answered before (I couldn't find it).

Thanks!

 

[hayhayday]

Billing\crediting is done in money not kwh so avoiding usage during peak is important.

 

[graubart]

Thanks hayhayhay, That would make sense, but my read of NEM-2 is that PG&E takes a look, once per year, at total generation and consumption, and then bills or refunds to true-up. I'm not understanding if they consider when the "excess" consumption took place or if/how they decide which kWh are the excess ones that they bill me for.

 

[BGbreeder]

Thanks hayhayhay, That would make sense, but my read of NEM-2 is that PG&E takes a look, once per year, at total generation and consumption, and then bills or refunds to true-up. I'm not understanding if they consider when the "excess" consumption took place or if/how they decide which kWh are the excess ones that they bill me for.

Please read the various write ups on this site. There are some excellent explanations.

 

[getakey]

Thanks hayhayhay, That would make sense, but my read of NEM-2 is that PG&E takes a look, once per year, at total generation and consumption, and then bills or refunds to true-up. I'm not understanding if they consider when the "excess" consumption took place or if/how they decide which kWh are the excess ones that they bill me for.

It keeps a running total of usage and credits at the time you use or export. So today, if you use 10 kWh off peak and export 10 kWh Peak, you will have a credit which is carried forward.

 

[wwu123]

To expand on getakey, it keeps a running $ total. It accrues the credits and debits converted to $ balances, not the kwh balances. Simply put it looks at the excess kwh consumption for each of the main TOU periods - peak, part-peak, off-peak, and multiplies by the TOU rate, to get the $ accruals.

So in your example, it's not 5000 kwh net consumption that matters, but also that it was consumed at peak rates - you'll accrue debits of 5000 kwh x $0.56 = $2800 owed. If we simplify that all your 5000 kwh solar was generated before 3 pm (when off-peak ends), it'll accrue credits of 5000 kwh x $0.25 = $1250. So you can see that WHEN you consume during TOU always matters (unless you have batteries to time-shift), as your debits/costs would be less if you can shift your household consumption more to off-peak.

It's slightly more complicated because there are seasonal rates (e.g. EV-2A peak is $0.43 in winter, not $0.56), as well as daily part-peak rates for some of your solar generation and consumption. So for each monthly bill, PG&E will take the net consumption in each of the three TOU periods and multiply each by the seasonal TOU rate to get $, and then add each to your accrual.

That last slight factor that impacts NEM2, but not NEM1, is non-bypassable charges - NBC's. In reality every 5-minute period you are exporting or importing, but your monthly bill only shows the net consumption. You might be exporting and importing at different times within the same one minute. You'll never be able to track this yourself unless you have a means of logging realtime net consumption, and accruing the totals. For example, it's theoretically possible that over the year you imported 105,000 kwh, and exported 100,000 kwh for the net of 5000 kwh - but you'd owe NBC's of ~$0.02/kwh on 100,000 kwh. The reality is NBC's for the year probably are modest <$100-200, and you can mostly ignore them for back-of-envelope ROI calcs....

 

[jjrandorin]

Thanks hayhayhay, That would make sense, but my read of NEM-2 is that PG&E takes a look, once per year, at total generation and consumption, and then bills or refunds to true-up. I'm not understanding if they consider when the "excess" consumption took place or if/how they decide which kWh are the excess ones that they bill me for.

Please read the various write ups on this site. There are some excellent explanations.

OP, since you seem to be talking about true up, there is a stickied thread where a few of our members have gone through, in detail, and explained a PGE true up example. You can find it stickied at the top of this subforum, but I will also link it here:

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

I was having difficulty in understanding where all the elements came from in my annual true-up bill and reached out the both @miimura and @Redhill_qik for some insight. From our discussions a document was created that is copied into this post. This document explains the factors that determine...

teslamotorsclub.com

Its probably the most comprehensive explanation you will find on this subject, which appears to me to be deliberately obtuse by the utilities.

 

[wwu123]

With all due respect to our hardworking moderator, that sticky is way overkill and unnecessarily complicated for someone who's first post on this whole site is asking to understand the basics of NEM and TOU essentially. Particularly the OP asked about solar specifically without Powerwalls, and solar-only PG&E customers do not get the complicated monthly B&W bill, nor such a complex annual true-up summary.

Probably two-thirds of what's explained there is utterly non-applicable to solar-only customers, but unless you already have either the solar bill or the solar + storage bills for a while, you'll not understand what is applicable or not there. The initial explanation there actually does not even mention the terms "TOU" or "peak" - it is implicit there that you already understand TOU, as it's jumping right into annual true-up.

And the fact that PG&E does annual true-up's for solar is probably what got confusing for the OP, that PG&E only asks you to actually pay up once a year. But because PG&E rates change about 7 times a year (if you include the two seasonal changes as well), one really needs to understand the monthly accrual first, because then you're only dealing with one set of TOU rates at a time (well, sometimes two, since the rates change on the 1st of the month, but most bills don't - but I think you get my drift)

I'm sure there are several very good AND simple explanations of NEM, NEM2, and TOU buried in this sub-forum, but that sticky is NOT that...

 

[jjrandorin]

With all due respect to our hardworking moderator, that sticky is way overkill and unnecessarily complicated for someone who's first post on this whole site is asking to understand the basics of NEM and TOU essentially. Particularly the OP asked about solar specifically without Powerwalls, and solar-only PG&E customers do not get the complicated monthly B&W bill, nor such a complex annual true-up summary.

Probably two-thirds of what's explained there is utterly non-applicable to solar-only customers, but unless you already have either the solar bill or the solar + storage bills for a while, you'll not understand what is applicable or not there. The initial explanation there actually does not even mention the terms "TOU" or "peak" - it is implicit there that you already understand TOU, as it's jumping right into annual true-up.

And the fact that PG&E does annual true-up's for solar is probably what got confusing for the OP, that PG&E only asks you to actually pay up once a year. But because PG&E rates change about 7 times a year (if you include the two seasonal changes as well), one really needs to understand the monthly accrual first, because then you're only dealing with one set of TOU rates at a time (well, sometimes two, since the rates change on the 1st of the month, but most bills don't - but I think you get my drift)

I'm sure there are several very good AND simple explanations of NEM, NEM2, and TOU buried in this sub-forum, but that sticky is NOT that...

I definitely missed the "no powerwalls or other storage" in the OPs post. Without storage, its simpler (well a bit). Unless its different in PGE land, you get credit for what you generate at the rate you would have been charged at the time for it, so if you generate solar during off peak, thats what you get credit for it at. Thats why the utilities moved the peak and off peak around, and forced everyone signing up onto TOU (but you know this already).

 

[wwu123]

I definitely missed the "no powerwalls or other storage" in the OPs post. Without storage, its simpler (well a bit). Unless its different in PGE land, you get credit for what you generate at the rate you would have been charged at the time for it, so if you generate solar during off peak, thats what you get credit for it at. Thats why the utilities moved the peak and off peak around, and forced everyone signing up onto TOU (but you know this already).

Yup, last night I was thinking there's probably a lot simpler way to have explained it, and you pretty much nailed it. For each kwh generated, you get credited in $ at the TOU rate applicable for that hour... if you're net-consuming loads during that hour, it offsets a kwh you would have pulled from the grid at the TOU rate, if you're not consuming, it gets exported, and you get the $ credited to your accrual for use later, either way it's the TOU rate for that hour.

 

[swedge]

Thanks hayhayhay, That would make sense, but my read of NEM-2 is that PG&E takes a look, once per year, at total generation and consumption, and then bills or refunds to true-up. I'm not understanding if they consider when the "excess" consumption took place or if/how they decide which kWh are the excess ones that they bill me for.

Welcome to solar! Congratulations on getting in before they killed NEM2.

PG&E does consider the time of consumption and of generation. Consumption is charged at the retail rate per kWh based on time and season, and generation is credited at the same retail rate minus a small fee of about 3¢ per kWh for "Non Bypassable Charges". The total monthly charges and credits are not billed monthly, but instead are accumulated in your account. You are billed around $10 each month for what they call "Minimum Delivery Charges", essentially their cost of the meter and billing, but in your true-up, this amount may be credited against the accumulated total amount you owe for the year.

At the end of the year, what you have already paid, around $120, is subtracted from the accumulated charges and credits. If you still owe, they bill you the difference as a "True-Up Adjustment". If your balance says they owe you, they keep it, sorry.

There are a few other possible outcomes because of "minimum" changes for NBC's or minimum "energy charges" and those monthly Minimum Delivery Charges. And in the event that you actually export more kWh than you import, you are considered a Net Generator and are credited at a small rate for the excess kWh. I got a $4.00 credit once!

To simplify, you pay ~$10 per month plus a yearly mystery bill. You monthly bill will show but not ask you to pay the accumulating totals. Typically your year end adjustment will be the largest of the accumulated totals minus what you have already paid, but not less than zero.

The concept is that you can run you meter foreward and backward, essentially loaning or borrowing power to and from the grid with the grid acting like a giant battery. This lets you, in effect, use your own solar at night, and to bank your summer excess to use in the winter. But because PG&E needs juice during peak time and has excess at night, they use the time of use rates to encourage import at night and export during peak times, and to accomplish this they apply the time-of-use rates to your in and out flows. But they do not credit retail for any more kWh than you bought from them at retail. They are not buying you juice, but rather giving it back to you when you need it.

I hope this helps. It is a very clever system because it is revenue neutral for PG&E, but lets you install only enough solar to supply your average needs over the entire year, day and night, summer and winter. But the details do get a bit complicated.

 

[h2ofun]

Welcome to solar! Congratulations on getting in before they killed NEM2.

PG&E does consider the time of consumption and of generation. Consumption is charged at the retail rate per kWh based on time and season, and generation is credited at the same retail rate minus a small fee of about 3¢ per kWh for "Non Bypassable Charges". The total monthly charges and credits are not billed monthly, but instead are accumulated in your account. You are billed around $10 each month for what they call "Minimum Delivery Charges", essentially their cost of the meter and billing, but in your true-up, this amount may be credited against the accumulated total amount you owe for the year.

At the end of the year, what you have already paid, around $120, is subtracted from the accumulated charges and credits. If you still owe, they bill you the difference as a "True-Up Adjustment". If your balance says they owe you, they keep it, sorry.

There are a few other possible outcomes because of "minimum" changes for NBC's or minimum "energy charges" and those monthly Minimum Delivery Charges. And in the event that you actually export more kWh than you import, you are considered a Net Generator and are credited at a small rate for the excess kWh. I got a $4.00 credit once!

To simplify, you pay ~$10 per month plus a yearly mystery bill. You monthly bill will show but not ask you to pay the accumulating totals. Typically your year end adjustment will be the largest of the accumulated totals minus what you have already paid, but not less than zero.

The concept is that you can run you meter foreward and backward, essentially loaning or borrowing power to and from the grid with the grid acting like a giant battery. This lets you, in effect, use your own solar at night, and to bank your summer excess to use in the winter. But because PG&E needs juice during peak time and has excess at night, they use the time of use rates to encourage import at night and export during peak times, and to accomplish this they apply the time-of-use rates to your in and out flows. But they do not credit retail for any more kWh than you bought from them at retail. They are not buying you juice, but rather giving it back to you when you need it.

I hope this helps. It is a very clever system because it is revenue neutral for PG&E, but lets you install only enough solar to supply your average needs over the entire year, day and night, summer and winter. But the details do get a bit complicated.

Yep, only allow solar install to the average amount needs