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Choosing Power Wall 2 mode Self Powered versus Time Based Control

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
I've just had my new 3 Power Wall 2's turned up with my existing 16KW of solar and I've begun playing with the modes. I'm wondering if anyone has done an analysis and knows pros and cons of Self Powering versus trying to optimize TOU ( PG&E E6 ) using the advanced Time Based Control.

I was also wondering about thoughts on modes combined with reserve power levels given I'm in a high risk fire area and high risk of PG&E power shut off to avoid fire risk. There has always been a few days notice before a PG&E power shutoff suggesting I could switch modes just before the shutoff to get a high charge. I'm also wondering if storm watch includes power shut offs given its typically done before a high offshore wind event.

I have been running a few days in self powered mode and I've used no PG&E power easily and this morning my powerwalls had 30% charge left when the sun came up. So my power generation now in September exceeds my nightly needs. But that suggests I'm not using the power wall capability to its maximum when I've got PG&E power. It also suggests I should be ok when I need backup.

When I began to play with setting the TOU in advanced, I realized my PG&E E6 TOU is in summer peak from 1PM till 7PM which is roughly me best power production. That means most of my solar power would be pushed into the PG&E grid to get credit for the peak E6 rate. But that implies my power walls might be starved since only power production before 1PM would be used for charging. But I could cheat and set the begin of the TOU to say 2 or 3PM so as to tweak things to get a reasonable power wall charge.

I'd be curious on peoples thoughts on the pros and cons of the modes given my situation and if tweaking the advanced TOU can be used to find a middle ground ... Or am I missing anything significant?

thanks
 

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arnolddeleon

Supporting Member
Jul 21, 2012
838
909
SF Bay Area
I'm also on grandfathered E-6 and I tweaked the times to make things charge/discharge more to what I want. I generally run with "Cost Savings". I've made peak start later so my powerwalls are discharging from 4 to 8 pm. I've also switched modes manually based on expected situations.

What are you objectives? Maximize savings? Help the grid? Consume your own solar? What's the balance among those?

One question is are you on NEM 1.0 or NEM 2.0? If you are on NEM 2.0 then you may want to avoid round trips to the grid if you are trying to maximize savings.

Since you have existing solar, double check that your PTO application for the batteries correctly reflects the size of your PV system. Right now I'm in the crazy situation of PG&E limiting what I'm credited on my PV production because Solar City/Tesla screwed up the size of my PV system in the paperwork. It's recorded as being much smaller than it actually is. I'm still waiting for resolution on that.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,530
10,725
Riverside Co. CA
I've just had my new 3 Power Wall 2's turned up with my existing 16KW of solar and I've begun playing with the modes. I'm wondering if anyone has done an analysis and knows pros and cons of Self Powering versus trying to optimize TOU ( PG&E E6 ) using the advanced Time Based Control.

I was also wondering about thoughts on modes combined with reserve power levels given I'm in a high risk fire area and high risk of PG&E power shut off to avoid fire risk. There has always been a few days notice before a PG&E power shutoff suggesting I could switch modes just before the shutoff to get a high charge. I'm also wondering if storm watch includes power shut offs given its typically done before a high offshore wind event.

I have been running a few days in self powered mode and I've used no PG&E power easily and this morning my powerwalls had 30% charge left when the sun came up. So my power generation now in September exceeds my nightly needs. But that suggests I'm not using the power wall capability to its maximum when I've got PG&E power. It also suggests I should be ok when I need backup.

When I began to play with setting the TOU in advanced, I realized my PG&E E6 TOU is in summer peak from 1PM till 7PM which is roughly me best power production. That means most of my solar power would be pushed into the PG&E grid to get credit for the peak E6 rate. But that implies my power walls might be starved since only power production before 1PM would be used for charging. But I could cheat and set the begin of the TOU to say 2 or 3PM so as to tweak things to get a reasonable power wall charge.

I'd be curious on peoples thoughts on the pros and cons of the modes given my situation and if tweaking the advanced TOU can be used to find a middle ground ... Or am I missing anything significant?

thanks

Its good to hear you finally got the nightmare install scenario you were dealing with situated in some form. I use self powered because I am not on a TOU rate yet, but many here do use the advanced modes.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
I'm also on grandfathered E-6 and I tweaked the times to make things charge/discharge more to what I want. I generally run with "Cost Savings". I've made peak start later so my powerwalls are discharging from 4 to 8 pm. I've also switched modes manually based on expected situations.

What are you objectives? Maximize savings? Help the grid? Consume your own solar? What's the balance among those?

One question is are you on NEM 1.0 or NEM 2.0? If you are on NEM 2.0 then you may want to avoid round trips to the grid if you are trying to maximize savings.

Since you have existing solar, double check that your PTO application for the batteries correctly reflects the size of your PV system. Right now I'm in the crazy situation of PG&E limiting what I'm credited on my PV production because Solar City/Tesla screwed up the size of my PV system in the paperwork. It's recorded as being much smaller than it actually is. I'm still waiting for resolution on that.

Thanks. What is NEM 1.0 vs 2.0? What is a PTO application? I installed my solar in 2008 and added more in 2012. If the PTO is the application to PG&E for interconnect, my addition was under a building permit but I didn't think to advise PG&E. My situation is slightly more complicated as I'm under Sonoma Clean Power rather than PG&E for reselling my power. Last year I got a check for $1000 for over production.

My main reason for adding the power walls was I wanted to be grid independent when PG&E shuts the power off during fire risk. I have 25,000 gallons of water in water tanks pumped by electric which can be used for fire fighting. I also have a 30,000 gallon pool and a gas pump as a backup. I had to live through 3 multi-day power outages and I don't want to do that again.

My goal for the entire system is to do my share in helping offset the looming "to much solar" problem in California by not being a user of power in the early evening while at the same time adding power during peak if needed while breaking even or making a small profit at years end.

I installed 12.6KW of solar in 2008 myself because my PG&E electric bill was about $900+ a month. That's over $10k per year. Since I bought all the parts myself back when the cost per watt was much higher, I spent just over $30k for my system. My payback was roughly 3 years. In 2012 I was still paying some PG&E so I added another 3000W on micro-inverters also myself and put myself past break even. I've gotten between $500 and $1000 back after true up each year since then. I stopped paying attention to peak, off peak etc.. and everything because everything was rosy. No need.

So I don't want to break my break even as I don't even know what is paid to me for power during the TOU times. I forgot how it works being 12 years. I'm reaching out to help me re-learn the various issues from people here who have done it. Nobody will have the same issues as I but now I want to learn what NEM 1.0 vs 2.0 and PTO are and do I need to update PG&E with my increased power or if that would help or hurt or is it Sonoma Clean Power. I asked both PG&E solar and the Sonoma Clean Power Solar expert about power wall issues and they both punted.

Any ideas, help appreciated as a brand new 3 day old power wall owner. Its working well.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
20200920_093331.jpg
Its good to hear you finally got the nightmare install scenario you were dealing with situated in some form. I use self powered because I am not on a TOU rate yet, but many here do use the advanced modes.

Well my nightmare continued for a while. The sub-contractor Tesla hired took a few months more but they did a nice install but Tesla wanted to finish the solar hookup - seemed silly! I had dug a trench making it trivial to run around my old panel pole a directly to the generation panel. The sub had installed this nice overhead tray system and pre-drilled holes above the trench. But when Tesla showed up, they hadn't looked at the project nor talked to the sub. They didn't bring any conduit. So they were going to Jerry Rig around the clean approach all ready by myself and the sub. I blew up at them. So one of them drove to Home Depot and bought some conduit and did it right.

But the ripped out my AC disconnects and threw them and a bunch of conduit and wires on my driveway and left. A huge mess plus I had all the Solar labelled as per code and they didn't label anything. I have no idea how the final inspection will go with no labels and no AC disconnects. There are breakers to shut off both Solar systems which might suffice on the latest code but I don't think you can leave labels off. We will see.

thanks
 

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,468
2,537
Northern California
My goal for the entire system is to do my share in helping offset the looming "to much solar" problem in California by not being a user of power in the early evening while at the same time adding power during peak if needed while breaking even or making a small profit at years end.
The Cost Savings or Balanced Mode is probably the best. It will use a bit of logic to maximize sending power to grid when you don't need it or it would be too expensive to buy from the grid (ie peak). You can adjust the time sequence to perform how you would like it too even if your costs don't reflect the same time. For example you could adjust for give back to the grid earlier than peak by just moving the time up. Or conversely you could move the off peak time to 9PM even when your plan reduces it at 8PM.

I tweak my reserve based on what I think my risk might be. If fire danger seems higher I up my reserve. I generally run 50% during lower risk times but will jump to 70% or more if risk is higher.

Note that PG&E gives lots of warning on PSPS and generally Tesla is at least a day ahead of an event. So I generally keep Storm Watch off and then turn it on off peak when PG&E calls a PSPS plan but before they execute it. Red Flag warnings are more hit or miss. Sometimes you get a Storm Watch and some times you don't.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
Thanks.

My very first thinking ( without to much detailed analysis) is I'm not going to make any additional money on the power walls since my summer peak ( when I get the most credit ) is from 1-7PM ( on E6) is when my solar was pumping its maximum power into the grid and getting top credit. If I use any of that to charge the power walls it seems I lose. Charging from first excess solar power ( solar minus house needs) till 1PM makes sense. The power walls are taking solar power when I get the most credit and simply using it over night when the rates are always low.

It seems with my current E6 rates, I might be best to use backup mode if its about $$. I have to study exactly what Cost Savings and Balanced mode allow precisely to know for sure. In 2022 the E6 stops and the peak moves into the evening after solar is gone. Then it seems the non peak times in early afternoon are the time to charge and then discharge into the grid until peak is over and then stop. Is there something wrong with this simplistic analysis?
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
Does the backup reserve apply to advanced mode? It would seem setting the backup reserve to a higher number would prevent using power wall discharge overnight when rates are low. Why waste power wall charge when rates are the lowest overnight when I just need to use valuable peak solar to recharge it. If I set the backup reserve high, the power walls will stop powering the house at night after hitting my set point yet helping the grid during the early evening. This satisfies my high priority of backup on a surprise power fail which is usually fairly short ( not all night) while I have good warning on a planned shutoff.

Am I missing some way to use time shift to do better in $$ than just solar if one has the E6 rates on NEM 1.0? It seems hard to beat and easy to mess up.
 

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,468
2,537
Northern California
I have to study exactly what Cost Savings and Balanced mode allow precisely to know for sure.
You'll never know. They don't expose the algorithm. ;)

And it can fail if weather or usage is not fairly consistent. For example assuming the default settings which is sort of based on PG&E EVA1, it will try to guess what your Thursday and Friday will be like. This means for example it could charge the PWs less and send more power to the grid. That works great until it's hotter and you use more AC or clouds move in and you get less solar those days. They you can find yourself buying power at peak because the PW gave it away earlier.

So just play around with the different options. But know that the time based modes will need a few days to "learn" what is normal before they will work at all and may adjust themselves a bit afterwards if events change. This whole heat/smoke thing was a bit challenging for them IMHO. I will be interesting what you power bill looks like. I already know August is going to be big because little solar from smoke and lots of AC use from the heat. And a few muli hour power outages in there too, but for me no PSPS recently. Missed it by 5 miles. :D
 

miimura

Well-Known Member
Aug 21, 2013
6,355
6,057
Los Altos, CA
Regarding the Powerwall modes, the best way is to just try each one and see what suits your expectations. When I was on EV-A and all my weekday generation was during Part-Peak hours, Cost Saving never worked well because it wouldn't charge anywhere near full and Tesla Energy support told me that it was not expected to work well in that situation. Balanced worked much better. Now that I'm on EV2-A, I don't think there would be much difference between Balanced and Cost Saving because most of my generation is during Off-Peak, when Cost Saving mode wants to charge.

E-6 starts changing sooner than you think. In January 2021, Peak moves to 3pm-8pm instead of 1pm-7pm and Part-Peak moves from 10am-1pm to noon-3pm. In 2022 Peak moves to 4-9pm and Part-Peak is 2-4pm. PG&E E-6 Tariff

The other thing you should be aware of is that PG&E Powerwall billing will disallow NEM credit for solar export in excess of what they estimate the equipment in their PTO docs should generate. If you did not apply for Interconnection of all the solar equipment that is currently generating, you had better self-consume all of it because PG&E won't give you credit for it. If they don't allow it, Sonoma Clean Power won't credit you for it either. The billing is passed through from PG&E to the CCAs.

PG&E Letter - Paired Storage Billing Update
 
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pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
You'll never know. They don't expose the algorithm. ;)

And it can fail if weather or usage is not fairly consistent. For example assuming the default settings which is sort of based on PG&E EVA1, it will try to guess what your Thursday and Friday will be like. This means for example it could charge the PWs less and send more power to the grid. That works great until it's hotter and you use more AC or clouds move in and you get less solar those days. They you can find yourself buying power at peak because the PW gave it away earlier.

So just play around with the different options. But know that the time based modes will need a few days to "learn" what is normal before they will work at all and may adjust themselves a bit afterwards if events change. This whole heat/smoke thing was a bit challenging for them IMHO. I will be interesting what you power bill looks like. I already know August is going to be big because little solar from smoke and lots of AC use from the heat. And a few muli hour power outages in there too, but for me no PSPS recently. Missed it by 5 miles. :D


I also missed the PSPS by about 5 miles. Lucky!

It seems like playing around and really knowing what is happening is tough as for years I tried to go over the monthly bills but there is so much variation in situation that I gave up and waited for my true-up. Waiting a year doesn't work too well. True-up integrates all the variables together and gives a solid result. When I put my initial solar in I shot for breakeven but came up short. That led me to add the additional capacity which got me over by the $500 or last year $1000 with Sonoma Clean Power.

My largest concern is losing ground seems more likely than gaining any. Do you think the power wall can actually improve on E6 until it changes? I hate to go back in and dig into all the PG&E bills graphs and analyze just to remain neutral. I'm not worried about losing the true-up money but it would seem sad to pay for those power walls and lose ground. Just using backup mode would avoid a lot of effort and probably cause the power wall life to improve.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
Regarding the Powerwall modes, the best way is to just try each one and see what suits your expectations. When I was on EV-A and all my weekday generation was during Part-Peak hours, Cost Saving never worked well because it wouldn't charge anywhere near full and Tesla Energy support told me that it was not expected to work well in that situation. Balanced worked much better. Now that I'm on EV2-A, I don't think there would be much difference between Balanced and Cost Saving because most of my generation is during Off-Peak, when Cost Saving mode wants to charge.

E-6 starts changing sooner than you think. In January 2021, Peak moves to 3pm-8pm instead of 1pm-7pm and Part-Peak moves from 10am-1pm to noon-3pm. In 2022 Peak moves to 4-9pm and Part-Peak is 2-4pm. PG&E E-6 Tariff

The other thing you should be aware of is that PG&E Powerwall billing will disallow NEM credit for solar export in excess of what they estimate the equipment in their PTO docs should generate. If you did not apply for Interconnection of all the solar equipment that is currently generating, you had better self-consume all of it because PG&E won't give you credit for it. If they don't allow it, Sonoma Clean Power won't credit you for it either. The billing is passed through from PG&E to the CCAs.

PG&E Letter - Paired Storage Billing Update

Thanks.

Good to know E6 is changing sooner. That should make it easier since solar production maximum and peak rates no longer overlap.

The tricky part is knowing if my expectations are being met. It takes a bit of effort to go over every statement to know if you are doing ok. And those are monthly. That's the only mechanism besides yearly true-up ( the acid test) where all the variables are integrated including Sonoma Clean Power.

I put off having a smart meter installed for an $8/mo charge. How would PG&E know what I should generate. They read my meter once a month which integrates a whole month of my solar minus my usage. They can't differentiate whether its my usage being down or solar being up. Since my original solar was 12.6KW and it actually produced it but has now fallen to about 11KW after 12 years and then I added about 3KW, it would be difficult to determine without a smart meter given I'm maybe 1.5KW above my original power. Is there something wrong with this thinking?

It seems what they are saying is that they won't pay for any power pushed into the grid that exceeds the total theoretical power a system should generate in a year in their location. But the home usage is deducted and they measure the total produced by solar minus home usage. Given home usage is a large variable, it would seem there is slop in their limit about equal to the home usage.

I looked at that letter posted and then my most recent statement and I can't find any reference to this. You would think I would have been dinged already if they could differentiate. I don't see anything on my latest statement suggesting any issues. I'll look a little closer. Any thoughts on how exactly and what exactly PG&E would look for in determining you were exceeding the PTO given they can't be sure of the home needs at any time or even over time? I used to have a Leaf to charge daily then sold it. I have a pool that I run variable times during the year. Now my girlfriend charges her Volt most days. So my usage has varied quite a bit from time to time.

The only thing that would look weird is if I had a 12.6KW PTO and they could measure instantaneous power and saw greater than 12.6KW during a short interval. But monthly meter reading gives them no visibility to instantaneous or short interval rates and they don't have a clue on my usage during short interval either. If I produced twice my PTO, it would show up in averages but not a 10% overage, I would think.
 
Last edited:

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,468
2,537
Northern California
I also missed the PSPS by about 5 miles. Lucky!

It seems like playing around and really knowing what is happening is tough as for years I tried to go over the monthly bills but there is so much variation in situation that I gave up and waited for my true-up. Waiting a year doesn't work too well. True-up integrates all the variables together and gives a solid result. When I put my initial solar in I shot for breakeven but came up short. That led me to add the additional capacity which got me over by the $500 or last year $1000 with Sonoma Clean Power.

My largest concern is losing ground seems more likely than gaining any. Do you think the power wall can actually improve on E6 until it changes? I hate to go back in and dig into all the PG&E bills graphs and analyze just to remain neutral. I'm not worried about losing the true-up money but it would seem sad to pay for those power walls and lose ground. Just using backup mode would avoid a lot of effort and probably cause the power wall life to improve.
Here's the problem. Whatever you conjure up regulators and the utility will find a way to screw it up. Rarely will it favor you.

In the end of the day you just have to decide (and operate) in the current situation that is best for you. That includes the environment, money, stability etc.

Just like buying a Tesla car, solar and especially the PWs were an investment we made to move the ball along. We had the money and felt that approach had the most likely positive return to change the world while benefiting us a little at the same time. Maybe not financially, but consciously.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
Here's the problem. Whatever you conjure up regulators and the utility will find a way to screw it up. Rarely will it favor you.

In the end of the day you just have to decide (and operate) in the current situation that is best for you. That includes the environment, money, stability etc.

Just like buying a Tesla car, solar and especially the PWs were an investment we made to move the ball along. We had the money and felt that approach had the most likely positive return to change the world while benefiting us a little at the same time. Maybe not financially, but consciously.

Agreed!.

So I'm trying to tap into the knowledge here so as to better understand what is "best" for me and how to operate in the way best for me. Its complicated. I'm surprised Tesla hasn't built a modeling program. With just this one thread I've learned about a number of things that might have slipped by had I not either asked or posed my situation. And I'm sure there is more.

Since my solar has paid back about 3 times over, I detest generators, like Tesla and its PWs, my main incentive here was backup due to PG&E shutoffs and water during power outages plus do my share in spreading solar generation over a wider time frame ( the silly duck curve problem)

Does anyone know if the SGIP Equity Resiliency Program is paying for PW installs if one meets the criteria. I'm in a High Fire location as per PG&E and rely on electric for pumped water. I just discovered this part of SGIP and recently wrote to the program. Does anyone know of any obstacles such as my system was just installed last week or having 3 PWs as a problem. Just thought I'd ask. The PG&E SGIP group responded with an automatic email saying they are running about a week behind so I hope to hear back this week.

Plus, does the SGIP program place restrictions or any other limitations that are additional problems.
 

miimura

Well-Known Member
Aug 21, 2013
6,355
6,057
Los Altos, CA
Thanks.

Good to know E6 is changing sooner. That should make it easier since solar production maximum and peak rates no longer overlap.

The tricky part is knowing if my expectations are being met. It takes a bit of effort to go over every statement to know if you are doing ok. And those are monthly. That's the only mechanism besides yearly true-up ( the acid test) where all the variables are integrated including Sonoma Clean Power.

I put off having a smart meter installed for an $8/mo charge. How would PG&E know what I should generate. They read my meter once a month which integrates a whole month of my solar minus my usage. They can't differentiate whether its my usage being down or solar being up. Since my original solar was 12.6KW and it actually produced it but has now fallen to about 11KW after 12 years and then I added about 3KW, it would be difficult to determine without a smart meter given I'm maybe 1.5KW above my original power. Is there something wrong with this thinking?

It seems what they are saying is that they won't pay for any power pushed into the grid that exceeds the total theoretical power a system should generate in a year in their location. But the home usage is deducted and they measure the total produced by solar minus home usage. Given home usage is a large variable, it would seem there is slop in their limit about equal to the home usage.

I looked at that letter posted and then my most recent statement and I can't find any reference to this. You would think I would have been dinged already if they could differentiate. I don't see anything on my latest statement suggesting any issues. I'll look a little closer. Any thoughts on how exactly and what exactly PG&E would look for in determining you were exceeding the PTO given they can't be sure of the home needs at any time or even over time? I used to have a Leaf to charge daily then sold it. I have a pool that I run variable times during the year. Now my girlfriend charges her Volt most days. So my usage has varied quite a bit from time to time.

The only thing that would look weird is if I had a 12.6KW PTO and they could measure instantaneous power and saw greater than 12.6KW during a short interval. But monthly meter reading gives them no visibility to instantaneous or short interval rates and they don't have a clue on my usage during short interval either. If I produced twice my PTO, it would show up in averages but not a 10% overage, I would think.
I have very simple goals for my Powerwall system. First, I want backup power. Second, I want to reduce my billable cost as much as possible through time shifting my solar generation. As you watch the system operating and observe the SOC% and the intra-day power flow, you can see if it's meeting your expectations.
2020-07-23r.jpg

To me, the chart above meets my requirements. It charges to full just before the start of Part-Peak, earns me Part-Peak and Peak NEM credits, and powers the house completely from 3pm-midnight. This makes for high Off-Peak billable kWh and negative billable Part-Peak and Peak kWh on EV2-A. This is the best possible outcome for my small solar system. This is the end of July. Now that we're past the middle of September, it's not charging to full, but still powering the house from 3pm-midnight. Eventually, it will start hitting the Reserve before midnight, then eventually around Thanksgiving it will struggle to have enough energy to cover the Peak hours 4-9pm. At that point my bills go up substantially until February.

If you have opted out of a SmartMeter and are on E-6, then you must have a digital TOU meter from before the SmartMeter transition. In that case, the meter is only reporting aggregated monthly flows in and out during each time period programmed into the meter. I don't think this meter will work for the NEM-Paired Storage billing system. Therefore, in order to give you PTO on your Powerwalls, they will probably force you to install a SmartMeter. The solar PTO documents include the actual equipment used and approximate orientations, so they can put it into a system like PVWatts to estimate your production. They will simply disallow NEM credits in excess of your estimated production as you can see from the billing tables in that other thread. I don't know what penalty there is for operating generating equipment without Permission To Operate.
 
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pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
I have very simple goals for my Powerwall system. First, I want backup power. Second, I want to reduce my billable cost as much as possible through time shifting my solar generation. As you watch the system operating and observe the SOC% and the intra-day power flow, you can see if it's meeting your expectations.
View attachment 590605
To me, the chart above meets my requirements. It charges to full just before the start of Part-Peak, earns me Part-Peak and Peak NEM credits, and powers the house completely from 3pm-midnight. This makes for high Off-Peak billable kWh and negative billable Part-Peak and Peak kWh on EV2-A. This is the best possible outcome for my small solar system. This is the end of July. Now that we're past the middle of September, it's not charging to full, but still powering the house from 3pm-midnight. Eventually, it will start hitting the Reserve before midnight, then eventually around Thanksgiving it will struggle to have enough energy to cover the Peak hours 4-9pm. At that point my bills go up substantially until February.

If you have opted out of a SmartMeter and are on E-6, then you must have a digital TOU meter from before the SmartMeter transition. In that case, the meter is only reporting aggregated monthly flows in and out during each time period programmed into the meter. I don't think this meter will work for the NEM-Paired Storage billing system. Therefore, in order to give you PTO on your Powerwalls, they will probably force you to install a SmartMeter. The solar PTO documents include the actual equipment used and approximate orientations, so they can put it into a system like PVWatts to estimate your production. They will simply disallow NEM credits in excess of your estimated production as you can see from the billing tables in that other thread. I don't know what penalty there is for operating generating equipment without Permission To Operate.

Makes sense.

Since Tesla handled everything on the PW addition, they applied for the permit and wouldn't they have applied for the PW PTO? I would think they would arrange for the PW permission to operate. PG&E came out and disconnected the mains for my main panel upgrade and returned and they turned the system up. My experience with Tesla has been weird to put it nicely. They didn't say anything and its been about 5 days and I have no idea if all is well or if there is a PTO and final yet to come. Looks like I better check. I think COVID has everything going weird. The building department did a video inspection. I applied for the 2008 PTO at 12.6KW and after my building department final, it was powered up working with PG&E. Then in around 2011 I applied for another building permit, put in about 3KW additional and it got its final and its just run ever since for 8-9 years. The building department said nothing about another PTO. ???
 

miimura

Well-Known Member
Aug 21, 2013
6,355
6,057
Los Altos, CA
Tesla will definitely apply for the Powerwall PTO with PG&E. @arnolddeleon got into this problem with disallowed NEM credits because Tesla did not list all his old solar on the interconnection paperwork when he added solar and Powerwalls, so he is not getting all his solar credit. He's trying to straighten it out, even though PG&E originally had all the information. It's not the building department's job to do anything about PG&E PTO. If I were you, I would call the PG&E solar department and check on the status of your Powerwall Interconnection application and find out what is listed for solar. You may have to give all you solar info to Tesla to get them to modify the interconnection application.
 

pgrovetom1

Member
Aug 27, 2019
59
7
Sonoma, CA
I have very simple goals for my Powerwall system. First, I want backup power. Second, I want to reduce my billable cost as much as possible through time shifting my solar generation. As you watch the system operating and observe the SOC% and the intra-day power flow, you can see if it's meeting your expectations.
View attachment 590605
To me, the chart above meets my requirements. It charges to full just before the start of Part-Peak, earns me Part-Peak and Peak NEM credits, and powers the house completely from 3pm-midnight. This makes for high Off-Peak billable kWh and negative billable Part-Peak and Peak kWh on EV2-A. This is the best possible outcome for my small solar system. This is the end of July. Now that we're past the middle of September, it's not charging to full, but still powering the house from 3pm-midnight. Eventually, it will start hitting the Reserve before midnight, then eventually around Thanksgiving it will struggle to have enough energy to cover the Peak hours 4-9pm. At that point my bills go up substantially until February.

If you have opted out of a SmartMeter and are on E-6, then you must have a digital TOU meter from before the SmartMeter transition. In that case, the meter is only reporting aggregated monthly flows in and out during each time period programmed into the meter. I don't think this meter will work for the NEM-Paired Storage billing system. Therefore, in order to give you PTO on your Powerwalls, they will probably force you to install a SmartMeter. The solar PTO documents include the actual equipment used and approximate orientations, so they can put it into a system like PVWatts to estimate your production. They will simply disallow NEM credits in excess of your estimated production as you can see from the billing tables in that other thread. I don't know what penalty there is for operating generating equipment without Permission To Operate.


Thanks. I think I've got balanced mode doing what I want by setting my E6 TOU times and adjusting my reserve to 65%. Each morning as my solar begins to come up, it is able to fully charge my PWs before 1PM and then at 1PM ( peak start) it begins back feeding PG&E fully. Then as solar and peak ends at about 7PM it lets the PWs power my home until it hits 65% and then I buy power from the grid all night. I can widen it to include the shoulder a bit with a lower reserve. So I can see how to tweak it to be sure I'm selling my solar to PG&E during peak ( or some shoulder) and then buying during the night after the evening shoulder ends. My house only uses about .9KW over night where I'm mostly buying power when the PWs hit the reserve I set.

We have a PG&E PSPS warning coming up tomorrow morning and I just entered Power Watch. So it appears Tesla has correctly identified a PSPS event and overrode my reserve. This week I had a 2 hour power fail and barely noticed. Its working pretty nicely so far!

thanks
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,530
10,725
Riverside Co. CA
We have a PG&E PSPS warning coming up tomorrow morning and I just entered Power Watch. So it appears Tesla has correctly identified a PSPS event and overrode my reserve. This week I had a 2 hour power fail and barely noticed. Its working pretty nicely so far!

thanks

Really nice to read the above, after all the difficulty you had this year getting it all situated. For me at least, the primary function of the powerwalls is to provide a person with power to their home for at least their essential loads during a power outage. All of the load shifting, etc, is all helpful in trying to cover the cost of the darn things, but the primary job is providing power.

For the most part, they do that very well. Sometimes we read here about things like @getakey 's issue with the neurio blaster failing, or @jeep1979 issue with the powerwalls being outside and not running because it was too cold and they couldnt warm up to accept a charge, but for the most part they work well in their primary function.

To me (as a person who has tesla solar panels, 2 tesla powerwalls, and a tesla vehicle), this describes tesla pretty well in fact (lol). Great products that work well for their primary purpose. Sometimes getting those products can be a challenge, depending on inventory, circumstances, etc. The more "custom" someones needs are, the more difficult it can be to work with tesla, but usually, in the end, the product you are purchasing itself is good enough to "slog through" that.

Congrats again @pgrovetom1 on getting everything up and running, and it working like you expect / want it to for the primary purpose!
 

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