PG&E NEM 2.0

[miimura]

Thanks.
When you say 'utility meter' , you mean to physically goto the ,meter to check the usage in real time ? or is their any other way to get this data ? I guess it takes 24 hours for this data to be posted on the PGE portal and then i can see some charts . Is that what you are referring to ?
In my case, part of it is just interest and excitement to monitor these things and also ultimately to charge my EV directly.
I mean why should i spend so much money to buy a power pack , when i have much bigger battery already at home , which needs to be charged . On weekends , uptill 2 PM the TOU rates are same as night time.

You can "stream" the data from the SmartMeter if you get the right kind of Zigbee device. Then you can do whatever you want with the data at almost any interval you care to measure and store.

Stream Your Data

The key point you will need to address is how you bridge this information gap between knowing what your solar and your utility meter is saying about your production and consumption and making decisions about how to control an EV charging. This can be done with OpenEVSE or SmartEVSE (European type) if you are a programmer, but I don't know of a commercial offering that will "just work" out of the box. Eventually, I would expect Tesla to offer this kind of software interface and integration, but it must not be a high priority since it's a relatively esoteric feature for most people.

 

[miimura]

I hope I do not get reported to the authorities. We are on PG&E NEM 1.

We installed our original PV system six years ago. It was sized properly with a string inverter for the 14x185w panels. I felt like we could use a few more at the time, but my wife nixed it. Regardless, our annual true-up was $150-$200 per year. We remained on the tiered rate structure because TOU made no sense during our blistering summers.

We purchased our Model S in May 2014, and in June had another contractor install 7x270w panels with micro inverters so as not to run through the string inverter. Clearly our addition exceeded the 1kW/10% threshold mentioned above. We were either ignorant of this rule, or we had forgotten the rule after the initial set-up.

Our annual true-ups after the addition have remained about the same; perhaps slightly less. We have not been visited upon by the solar police.

I really do not know how PG&E audits their customers who have rooftop solar. Perhaps they just have some sort of filter to be on the lookout for wild reductions in deliveries and do not look at generation and receipt. Since the Tesla is offsetting most, if not all, of our second installation, we have slid through their internal review process, if they even have one.

As indicated in the first post in this thread, PG&E reached the NEM 2.0 threshold in December 2016. If you installed solar before that time, there was no significant limitation on how you could expand your solar system, within reason. Normally PG&E is notified by installers when new solar equipment is interconnected and many building departments notify PG&E when significant electrical loads are signed off.

 

[miimura]

Can someone suggest a link , how does Powerwall logic work. How does it decide, when to charge ?
As i understand, the best way would be to connect to the smart meter zigbee and get Net Metering data if its +/-
If i decide to charge my EV on solar , it would be similar logic as well.

The Tesla Gateway that is installed with the PowerWall contains a device that uses CTs (Current Transformers) to measure the power flowing through the utility meter and (I think) the critical loads panel. In a PowerWall installation that includes solar, the default mode of operation is Self Consumption. In this mode the system tries to minimize all grid use by using as much solar as possible to charge the batteries and to satisfy all household loads from either solar or the battery. The solar will only go to the grid when the batteries are full and loads will only draw from the grid when the batteries are empty or the power requirement exceeds the capacity of the PowerWall(s).

 

[Sun007]

As indicated in the first post in this thread, PG&E reached the NEM 2.0 threshold in December 2016. If you installed solar before that time, there was no significant limitation on how you could expand your solar system, within reason. Normally PG&E is notified by installers when new solar equipment is interconnected and many building departments notify PG&E when significant electrical loads are signed off.

Its not just PGE , if the 7x270w panels have a impact on the electrical panel load , it may need a city code review.
May be if you have a 200Amp electric panel , this may not be big enough

 

[Sun007]

Miimura / Others,
It was suggested, to use the PGE smart meter to read the consumption data.
Is there any way to get this data or download this data , broken down on a hourly or daily basis ?

I have had solar inverter working for 2 days , and generating electricity.
When i goto the opower portal , via the PGE web site to look up my consumption.
Surprise surprise. There is no change. as if the inverter is not generating anything.
The bar charts look , just like pre solar days.
While some charts have a disclaimer of *estimated , i believe all the charts are estimated , and basically bogus.
Not quite sure , of what is going on.
My PGE agreement is still not processed , but that should not alter the energy consumption charts.
I should have 0 or negative charts at day time , but they look exactly like before solar.

In Fact in the past also i noticed that the consumption data was incorrectly displayed by an hour earlier ( i plug my car at 10AM , it shows spike at 9 AM) . now it looks the dates are also incorrect.
O power , what r u doing ?

ok , just realized , i will walk to the meter tomorrow to look at the consumption at day time.

 

[miimura]

First, if you don't have the final Permission to Operate letter from PG&E, your solar should not be turned on. Until they activate you as a solar customer, the meter may not register negative values, or they may assume negative data is erroneous.

You can download your SmartMeter data by logging into your account, clicking through My Energy Usage which takes you to an oPower site, then look for the "Green Button, Download my data" button. You can download it a couple different ways, but I usually take CSV by billing cycle.

 

[mike-415]

Reading the bills provided above and the NEM 2 tariff, I cannot make sense of how the NBC and NBC adjustment calculations work. I would love to be able to give you some estimation of how your bills might change, but my initial guess at NBCs was far higher than what was actually billed to the customer shown above.

Reviving this old thread. Did anyone ever figure out how the PG&E NBC and NBC adjustment are calculated? I’m trying to model my future bills and these are throwing me off!

 

[miimura]

Reviving this old thread. Did anyone ever figure out how the PG&E NBC and NBC adjustment are calculated? I’m trying to model my future bills and these are throwing me off!

I have not made any progress nor any actual effort on this front. I want to put more solar but the 1kW allowed if I want to stay on NEM 1.0 hardly seems worthwhile. I may hassle the PG&E Solar department to explain it in more detail on the premise of doing an accurate estimation of my costs if I were to change to NEM 2.0.

Ok, I just did a quick Google search on this subject again and found an article that implied that the tariff line items charged as NBCs are not included in the energy charges for the same kWh where the NBCs apply. That is different than the way I did the calculation before. However, the article did not offer any explanation for how the NBC Adjustment was calculated. The article also said that the NBCs were 2-3c/kWh while I seem to recall that I had calculated just over 5c/kWh by adding up the indicated line items in the tariff. I will probably have another go at figuring this out soon.

 

[Bigtanuki]

@zamallchi Why did you decide to choose the option to convert your entire system to NEM2 rather than the option to keep existing solar on NEM1 and put expansion on NEM2? Did you calculate a savings for the first option? For such a large expansion (depends on overall system size), I would guess the extra savings for keeping original on NEM1 would offset extra meter cost.

@miimura Do you know if adding a Powerwall to existing solar on NEM1 will trigger an NEM2 upgrade? (Technically it adds 5kW of generation, but from what I now I think I understand from many discussions, that is typically not fed back to grid at peak solar production the way they have set it up).

I've seen several references to the PWs being additional generation but I don't think that's true since, by design, the batteries are prevented from feeding the grid by the gateway and existing PW firmware. My neighbor up the street installed 3 PWs about the same time I did and he wasn't forced to NEM2.

 

[Sun007]

Question on hourly energy aggregation with NEM2 ?

In regards to Solar , I wanted to understand , if the meters return 2 separate readings per hour , one consumption , and 2nd for solar generation and send it back, and its totaled at the server OR this calculation is done at the meter itself , and only one value is set back by meter , per hour
e.g - In one hour
Consumption- 5 KWH
Generation - (-2) KWH
Does the Meter returns both the data values OR the meter returns only 3 KWH single value ?

I ask , as with NEM2 they have introduced a $.03 fee on any consumption. Its not clear , in the above example if the fee on consumption is on net i.e. 3 KWH or absolute i.e. 5 KWH

Basically if within an hour if i consume and produce , but the total is zero, will the meter report 0 or the meter reports consumption and generation separately withing the hour , like +2 and -2 ?

I know if in one hour i generate 5 KWH
and in another hour i consume 5KWH , i still pay the .03 fee on the consumption

 

[Ampster]

In regards to Solar , I wanted to understand , if the meters return 2 separate readings per hour , one consumption , and 2nd for solar generation and send it back, and its totaled at the server OR this calculation is done at the meter itself , and only one value is set back by meter , per hour

As far as I know my single PG&E meter sends a net number every 15 minutes. I have observed my generation via solaredge monitoring and my meter date via Rainforest Eagle to reach the above conclusion. During the day I have observed what happens when I have generation and I add load which reduce the generation (negative number). I have another property in SCE territory and the conclusion is the same, the meter only reports a net number.

 

[miimura]

As far as I know my single PG&E meter sends a net number every 15 minutes. I have observed my generation via solaredge monitoring and my meter date via Rainforest Eagle to reach the above conclusion. During the day I have observed what happens when I have generation and I add load which reduce the generation (negative number). I have another property in SCE territory and the conclusion is the same, the meter only reports a net number.

The question you're trying to answer above is very specific to Net Meter Aggregation. This is a scheme where you can have multiple meters in a Net Metering arrangement (on the same or adjacent properties) and the generation from one can be apportioned to offset the usage and their charges on the other meters. It's relatively straight forward before you start considering Non-Bypassable Charges. The question is very specific and without knowing exactly how they calculate the NBCs, I could not provide a meaningful answer, so I didn't post. This is really a question for the PG&E Solar Department - 1-877-743-4112

 

[Ampster]

The question you're trying to answer above is very specific to Net Meter Aggregation.

Aha, I didn't see that at first. I thought it was generally about NEM.
I agree, PG&E is the best entity to answer that question, My experience with SCE and NEM Aggregation was not good and with the complications of Non Bypassable Charges it has become even more complicated. I was on NEM Aggregation (NEM 1.0) for some properties I owned and it took SCE six months to get me a bill. It was done by a clerk on a spreadsheet and to this day I am not sure it was correct. One of the things that made it complicated was that the meter with solar which generated the excess kWhrs was on a residential TOU rate. The other meters in the aggregation were commercial meters which had different TOU rates plus some fixed charges. Even though this aggregation generated more kWhrs than it consumed I always had a bill of about $25 which represented the fixed charges for each of those comercial meters. There may be an analogy to NEM 2.0 and NBCs and we have yet to see how that plays out.

 

[Sun007]

Actually my question was for a single meter only, generally about NEM
. I am trying to understand , what would be the best way to reduce the NEM 2 changes for a singe meter , when you are both producing and consuming

I trying to understand, withing an hour , if my solar is generating say 2 KWH continuously. Should i try to use my toaster and my microwave and my cooking range in a serial order to keep my demand low or does it not mater , and only the aggregate consumption counts ?

If the aggregation is done per hour , then , then withing an hour, it should not matter if i consumption is very heavily for 10 mins and then nothing
If the aggregation is done every 15 mins, then the consumption should be averaged with the 15 mins.
If the meter reads both values separately , then we need to serialize the loads to minimize the NEM 2 charges

The pge online charts are for display purpose and the obviously aggregate the final values . But for the NEM 2 consumption charges , it may be a different story.

By NEM charges i meant Non Bypassable Charges

 

[miimura]

If PG&E My Energy shows bars in 1 hour increments, that's the only data they have. My account used to be set up for 15 minute intervals, but after having solar for about 4 years, they changed it to 1 hour intervals. So, if your meter is on one hour intervals and you net export 1 kWh in the first half of the hour, and net consume 1 kWh in the second half of the hour, it will still report zero and I believe they must bill based on those figures.

 

[aesculus]

So, if your meter is on one hour intervals and you net export 1 kWh in the first half of the hour, and net consume 1 kWh in the second half of the hour, it will still report zero and I believe they must bill based on those figures.

This is not how I read the NEM 2 from PG&E. In this scenario you do break even for the power cost, but you will pay $.03 for every kWh that you move across the meter to your premise, no matter how much credit you have. This is the primary difference between NEM 1 and NEM 2. For NEM 1 you never got charged if you had a balance.

 

[aesculus]

One thing that bothers me with NEM 2 is that they are allowed to have you provide the peak production capability of your units. With a NEM 1 system this was the CEC calculation. With NEM 2 its the rated efficiency of the panels minus the inverter losses.

What really gets me though is that you could essentially use much of your solar production before any net takes place and the determination of your system is not the maximum you agree to send back to the utility, but the theoretical maximum that you COULD send back if you turned every device in your premise off and only produced energy to send to the grid. I think that's unfair.

So basically they are adding up all the nameplate solar minus the inverter(s) efficiency and don't care how much you will ever send to them. You may never send them more than 1 kWh of energy on a 5 kW system, but they will still see it as a 5 kW system.

 

[Ampster]

What really gets me though is that you could essentially use much of your solar production before any net takes place and the determination of your system is not the maximum you agree to send back to the utility, but the theoretical maximum that you COULD send back if you turned every device in your premise off and only produced energy to send to the grid. I think that's unfair.

I have some systems on NEM 1.0 and a new system on NEM 2.0 and there were no system size limitations put on those systems that I know of. As far as I know I never agreed to send any production back to the utility. I haven't yet received the PTO on the recent system that will be under NEM 2.0 and the only thing that bugs me is that I will be paying Non Bypassable Charges. Depending on how that works out I may try to self consume as much of my production as I can. Under NEM 1.0 I load shifted and consumed more than I generated but still had a negetive bill. For the new system I also have a Powerwall on order to facilitate self consumption.

 

[miimura]

This is not how I read the NEM 2 from PG&E. In this scenario you do break even for the power cost, but you will pay $.03 for every kWh that you move across the meter to your premise, no matter how much credit you have. This is the primary difference between NEM 1 and NEM 2. For NEM 1 you never got charged if you had a balance.

My point was that if they can't measure it, they can't charge you for it. If you have a 1 hour interval meter, they can only bill you for the net usage in that whole hour. If it's positive, it's subject to NBCs, if it's negative, you get credits for it. However, if they suspect you have very peaky plus and minus usage, they could change your meter to 15 minute intervals at your next true-up. My meter used to report 15 minute intervals, for no discernable reason.

 

[aesculus]

My point was that if they can't measure it, they can't charge you for it.

With NEM 2.0, the meter is not the only device they will be able to query. NEM 2.0 came about with enhancements to the inverters (BTW there is a working group involved in trying to decide how much of this should be retrofitted to legacy inverters).

Phase 1 includes feature that offer grid stability and volt/var coordination etc.

Phase 2 will set a common language for how inverters, solar energy systems, and utility systems talk to one another. Systems must also be able to communicate over the internet, although they can’t yet be required to have an internet connection because California has yet to decide who should pay for internet connection, the utility or the homeowner. The new date appears to be February 2019.

Phase 3 will cover additional inverter functions, like data monitoring, remote connection and disconnection, and maximum power controls.

BTW all of this applies to solar inverters and energy storage systems. Not sure about wind generation but I suspect it's covered here too.

If you have a 1 hour interval meter, they can only bill you for the net usage in that whole hour. If it's positive, it's subject to NBCs, if it's negative, you get credits for it. However, if they suspect you have very peaky plus and minus usage, they could change your meter to 15 minute intervals at your next true-up. My meter used to report 15 minute intervals, for no discernable reason.

The 15 min vs 1 hr is just the window you have from which they will decide to "settle up for NBCs". In the end of the day I doubt that makes a big difference, but with AC cycling maybe some.

This is a good summary blog of how NEM 2.0 works. They use EV-A as an example too.

The Ultimate Guide to NEM 2.0: Non-Bypassable Charges Explained

Here is another blog by same person that talks about how NEM is evolving
How Net Metering is Evolving: Three Changes You Need to Know

If you really want to look under the covers see the Rule 21 working group notes.
Smart Inverter Working Group

This one is an interesting read for the current issue debate and a list of who's who in the process
http://www.cpuc.ca.gov/uploadedFile...I/itcn/R1707007WorkingGroupOneFinalReport.pdf