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Tesla Powerwall Question

mattack4000

Active Member
Oct 1, 2017
2,424
952
CA
When I had my Tesla Solar installed, I moved away from the Powerwall due to the cost and NEM. Yet after calculating how much my 1.4kw battery backup system is, where NEM2 is heading and what I am seeing as actual productions from my new solar, I am starting to think PW2 might not be a bad idea. I have a couple things I want to toss you guys to see if makes sense.

1. I have Tesla Solar on my E facing roof, 3.8kw making about 20kwh per day (likely more, but estimate conservative number). Sunpower 2.0kw making about 9kwh per day. They are on separate inverters on the same 200a main panel. My question is can I charge the battery with both solar or can it only be one or the other?

2. My house has 200A service to the main and 100A to the sub panel. I understand one PW is not enough to charge cars or run my AC, yet it is plenty to run the rest of the items in the house. How does Tesla setup the PW to not power the other items that I can't run or do I trigger overload?

3. I would be interested in the cost saving component due to the NEM2 and EV2-A. I can power the house and charge the battery from empty to full before 3PM barring bad weather. If anything, I might even overflow since I get 13kw before 3PM net of my usage. What happen if I generate more, I am assuming I pass it back to the grid without getting anything? This is after my usage too as I only burn about .8kwh during the day 1.2kwh at night. My 14SEER AC and the cars are what kill my electric bill.

4. Does the battery always default to sending all power to the house before charging or can you change it to not use it? In my scenario, I am hoping to use all solar for home usage as soon as it starts generating. Any excess should go back to the battery (I will likely set it to 10-15% reserve). I should start feeding the battery at about 9AM and the battery should be full by 2 or 3PM. I want to then stop charging the battery and use battery only except when I hit 15%. In the perfect world, that would be 11PM. That would basically shoot my peak electric bill to zero and I am really paying for the car's charging and a few kw I use at night. If I get lucky and have extras, I will drain it overnight and have 2 or 3kw ready for the morning. Rinse and repeat. I guess on rainy days I would be screwed as I would have to buy everything from the grid.

5, What is the labor cost for one PW2? I already have the panel and their solar.

Am I off base or not?
 

bob_p

Active Member
Apr 5, 2012
3,706
2,814
You will need both a PowerWall 2 and a Tesla Backup Gateway. The Gateway is the gatekeeper channeling power between the solar panel inverter/microinverters, PowerWall(s) and grid.

The Tesla app provides several operation modes for the system. We normally run our system in "Self-Powered" mode with a 20% power reserve. When solar power is being generated, it goes first to power the house and any excess goes to charging the PowerWalls. If there isn't enough (or any) solar power, the PowerWalls will provide power until they hit 20% - and the rest of the energy comes from the grid.

When we have days of full sun, we may have a few hours late in the day when excess solar power is routed to the grid after our 4 PowerWalls are full. And because we don't have a solar "buyback" plan, we're probably not getting any credit for that power. Though because our electricity rates are so low ($.091 per KWh), we're not too concerned about providing the grid a little bit of extra power.

We may shift to a time-of-use plan that would provide us free electricity from 9PM to 9AM every day. If we do that, we'll shift to the Advanced Time-based Control operating mode, and have the system maximize solar & PowerWall use from 9AM to 9PM, and not use any PowerWall power between 9PM to 9AM. We've already set our Tesla S and X to do scheduled charging starting at 10PM each night, so our EV charging is ready to take advantage of the free overnight power. [Of course this assumes the utility doesn't exclude homes with battery storage from their free nights plans.]

In the OP's case - it may be necessary to split the house circuits into two panels - one panel powered by the Tesla Gateway and the other panel (HVAC, EV charging) from the grid.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,654
10,899
Riverside Co. CA
1. Not sure, I only have one system so no idea on this.

2. They install a "backup loads" panel (breaker box) and move all circuits to be backed up to that breaker box. Any powerwall install is going to do that, unless you were to get enough powerwalls to backup your whole house AND run the AC.. like 3-4. Most people have a backup loads panel and a few items not on it. I myself have one, and the only thing I have NOT backed up is my 60 amp tesla wall connector, so my main panel has 2 breakers in it... one for the tesla wall connector, and one feeding the backup panel (and the main breaker to the home)

3. In general, when your solar turns on, it starts powering the house automatically, as it does now, and any excess goes to the powerwall. How (and when) the powerwall(s) stop accepting solar power and shunt power to the grid depends on what mode you have the powerwalls in. I use mine in " self powered" mode, which means every day my powerwalls accept all excess solar till full, then sit idly by until the home load can no longer be covered by solar, and then provide power to make up the differece / take over. My two powerwalls cover my usage all night, except for car charging.

I have my reserve set at 30% now, because Its more important to me to have power if the power goes out overnight until the sun comes up than it is to wring the last drop of power out of my powerwalls.... but I am still on NEM 1.0 and have full net metering with smaller non bypassable charges.

4. the two advanced tesla modes allow covering the peak period with your powerwall. In all cases, solar, when on, will power your home if it is generating enough to power the home. Where the extra comes from if solar is NOT generating enough to power your home depends on what setting you are in. one of the modes is specifically to cover time of use peak pricing.
 

woferry

Member
Mar 4, 2019
405
478
San Jose, CA
The maximum charge rate of a single PW is 5kW. So by the nameplate ratings of your inverters if both of your inverters were on the PW side of the Gateway's transfer switch, when your house was islanded from the grid during an outage both inverters combined could produce more energy than the PW could absorb. Now it's close enough that the house might make up the difference, but that seems hard to guarantee. If the excess wasn't absorbed by something your mini-grid voltage could spike and everything (solar inverters and the Powerwall inverter) could shut down, leaving you with no power until you reset the system. In my case (1 PW, 2 5.2kW inverters) Tesla put one inverter on the PW side of the Gateway and one on the other side. This means if the grid goes out one inverter shuts down, but it keeps things balanced. At 5.8kW total I could see that design decision going either way. I hope to add a second PW to my system some day, and expect that the second inverter would be moved to the other side of the Gateway at that time.

In terms of loads, at least for my house Tesla clearly wasn't too concerned about the total power, they set me up for whole-house backup on a single PW, and the total amperage of the breakers can well exceed the 5kW sustanied / 7kW peak a single PW supports. I do think they care about breaker size, as far as I know with a single PW they won't allow any breakers above 30A to be in the PW-powered panel(s), since that one load could exceed the PW's inverter rating (my biggest breaker was 30A, so no problem there). But I think they largely view it as the customer's responsibility to not turn on more loads than the PW can handle during an outage, if I turned everything in my house on at once my PW would be protecting itself (turning off) pretty quickly, but in normal usage I have yet to exceed 5kW, the only time I even get close is when cooking. Depending on how your existing panels are wired, it seems most likely that they'd install a new panel for backed-up loads, and probably keep the panel closest (wiring-wise) to the meter for any loads not to be backed-up (in my case the only thing in that panel besides the Gateway's breaker is my second inverter). For loads in this panel beyond the Gateway, while those loads would lose power during a grid outage, it is still possible for the PW to "power" those loads when the grid is up. It all depends on how the Gateway's Current Transformers (CTs) are connected and what circuits they do/don't monitor, the Gateway can still sense loads in that panel and increase Powerwall inverter's output to try to cover them rather than have that power come from the grid if you wish, at the trade-off of draining the battery faster (it's worth noting that whatever the Gateway doesn't monitor is invisible to the app, so if you put the AC and/or car charger outside of the Gateway's CTs their loads simply won't show in the app, and the app's reported grid consumption/production data won't match your meter).

Cost-wise the PW is pretty independent from solar from what I've seen, even though I had both installed together it was largely different crews handling each. So I don't think there's really any benefit or penalty to already having solar. I think I've heard on this forum that installation costs tend to run between 1-3k depending on just how much they have to do. The Gateway is a separate charge beyond the Powerwall itself, since one Gateway can support multiple PWs.
 

gpez

Member
Apr 25, 2019
689
567
USA
The maximum charge rate of a single PW is 5kW. So by the nameplate ratings of your inverters if both of your inverters were on the PW side of the Gateway's transfer switch, when your house was islanded from the grid during an outage both inverters combined could produce more energy than the PW could absorb. Now it's close enough that the house might make up the difference, but that seems hard to guarantee. If the excess wasn't absorbed by something your mini-grid voltage could spike and everything (solar inverters and the Powerwall inverter) could shut down, leaving you with no power until you reset the system. In my case (1 PW, 2 5.2kW inverters) Tesla put one inverter on the PW side of the Gateway and one on the other side. This means if the grid goes out one inverter shuts down, but it keeps things balanced. At 5.8kW total I could see that design decision going either way. I hope to add a second PW to my system some day, and expect that the second inverter would be moved to the other side of the Gateway at that time.

I have 1 Powerwall and my max production is about 6.4kw on the sunniest of days for my 8.5kw panel rated / 6.7kw inverter rated system. During a grid outage with a full battery and max solar I could potentially exceed the 5kw continuous inverter limit so I use the Over Frequency Power Limit functionality of my inverters to ramp down production and avoid this problem. See page 6 of https://enphase.com/sites/default/f...Considerations-AC-Coupling-Micros-Battery.pdf.
 

GenSao

Member
Aug 3, 2017
550
938
Pleasant Hill, CA
1. Yes, you can charge a Powerwall with both 3.8 kW and 2.0 kW solar arrays. Per Tesla support/FAQ, "To ensure reliable operation during power outages, at least one Powerwall is required for each 7.6 kW AC of solar included in the backup circuit." Your total 5.8 kW of solar falls within the 7.6 kW limitation.

2. With one Powerwall, Tesla will move all your 120V household loads and solar breakers to a new sub panel. All the remaining loads will stay in the existing electrical panel(s). The Tesla Backup Gateway will be installed between the backup sub panel and the main panel. See below diagram.

Capture.JPG


3. Under CA Net Energy Metering (NEM) rules, you will get paid for the surplus power you provide the grid.

4. There are various modes. Use the Backup-Only mode to force the Powerwall to charge the batteries from solar. Self Powered and Time Based Control modes are default options. You'll likely use the Time Based Control-Cost Savings to maximize savings. If the default behavior does not work for you, you can manually make changes or use are custom third party apps.

5. You'll likely need additional supporting hardware. The labor cost is a standard price based on the number of Powerwalls installed. If your installation is harder, Tesla will not charge you more. Inversely, if your installation is easier, Tesla will not give you a discount. See below chart for an estimate for Tesla California pricing.

Capture.JPG


For some reason, there is a discount in labor for two Powerwalls.
 

mattack4000

Active Member
Oct 1, 2017
2,424
952
CA
Thanks guys. Couple things, I believe Tesla changed their installation cost to variable? I believe it reads $2500-4500 now?

Going back to the subpanel for a sec. I have a situation where my main 200A only has the 100A house panel, two solar, my AC and my car charger. In theory, I can run the new subpanel and tie the sub panel with the two solar to it. The problem is that my 100A subpanel has a 40A EVSE in there, will that cause a problem during inspection

Since my intend is to not pull grid power to charge the battery, I think under the new rule I can in theory offload my excess back tot he grid for like .10 cents? I figure net of my usage, I can fill the battery in 4-5 hours. That would mean I must have 2-3 hours where I am just generating excess before peak time.

We rarely lose power here, I am not concern about draining down my battery to 15% nightly and then wait until the morning before I can charge the battery and have power again. My house only runs about .6-.8kwh at night, so it shouldn't be a problem other than maybe dying from being too hot or something.

The 5kw limit isn't a concern to me because my panels face both sides of the sky evenly. I think at peak I can generate maybe 3.5kw combined net of my usage.
 

GenSao

Member
Aug 3, 2017
550
938
Pleasant Hill, CA
Thanks guys. Couple things, I believe Tesla changed their installation cost to variable? I believe it reads $2500-4500 now?

Going back to the subpanel for a sec. I have a situation where my main 200A only has the 100A house panel, two solar, my AC and my car charger. In theory, I can run the new subpanel and tie the sub panel with the two solar to it. The problem is that my 100A subpanel has a 40A EVSE in there, will that cause a problem during inspection

Since my intend is to not pull grid power to charge the battery, I think under the new rule I can in theory offload my excess back tot he grid for like .10 cents? I figure net of my usage, I can fill the battery in 4-5 hours. That would mean I must have 2-3 hours where I am just generating excess before peak time.

We rarely lose power here, I am not concern about draining down my battery to 15% nightly and then wait until the morning before I can charge the battery and have power again. My house only runs about .6-.8kwh at night, so it shouldn't be a problem other than maybe dying from being too hot or something.

The 5kw limit isn't a concern to me because my panels face both sides of the sky evenly. I think at peak I can generate maybe 3.5kw combined net of my usage.

Yes, Tesla's install price is $2,500 to $4,500. To install a single Powerwall, the cost is $3,000. This excludes the optional cost of a main panel replacement which can be $2,000 to $3,000 (you will not likely need this as your main panel is 200A already).

Depends on how the house is wired, location of the stronger 240V breakers, and distance between panels. Without much details to go by, your installer may install a new backup load center adjacent to the old panel. Assuming only one Powerwall, they would move all the 120V to the new panel. The EV charger and other 240 V loads would remain. Alternatively, the installer may move the 240 V loads directly to your main 200 A panel and convert the 100 A sub panel to a backup loads panel.

Note, Tesla prefers to have the solar circuit breakers and Powerwall circuit breakers next to each other. Either at the bottom of the back up load sub panel or in a "generation" sub panel that connects directly to the Tesla Gateway.

When paired with solar, by default the Powerwall will never charge from the grid (except when Storm Watch mode is activated). You will be able to offload your excess at the prevailing market rate. For EV2-A, this would be $0.1686/kWH in the summer and winter off-peak during most of the day.

It is best to use Time Based Control - Cost Savings to maximize savings. Fill the batteries during the off-peak period and cover home use during part-peak and peak periods. Directly offload the maximum solar during summer peak ($0.4811/kWH) and part-peak ($0.37061/kWH) periods.
 
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dortor4ev

Member
Feb 24, 2013
210
336
San Jose, CA
When I had my Tesla Solar installed, I moved away from the Powerwall due to the cost and NEM. Yet after calculating how much my 1.4kw battery backup system is, where NEM2 is heading and what I am seeing as actual productions from my new solar, I am starting to think PW2 might not be a bad idea. I have a couple things I want to toss you guys to see if makes sense.

1. I have Tesla Solar on my E facing roof, 3.8kw making about 20kwh per day (likely more, but estimate conservative number). Sunpower 2.0kw making about 9kwh per day. They are on separate inverters on the same 200a main panel. My question is can I charge the battery with both solar or can it only be one or the other?

You can charge the batteries with both solars - as noted above Tesla will combine the circuits for the Solar so that both solar systems will "dump" excess solar into batteries or the grid depending on your current Powerwall settings. There is a limit on the number of inverters the Powerwall can control, but I doubt you're above it.

2. My house has 200A service to the main and 100A to the sub panel. I understand one PW is not enough to charge cars or run my AC, yet it is plenty to run the rest of the items in the house. How does Tesla setup the PW to not power the other items that I can't run or do I trigger overload?

You can have them split your panels (expensive and a hassle) it's a matter of controlling your usage while on battery power - if the Powerwalls get overloaded they just shutdown (blackout) so they won't let themselves be damaged.

I'd recommend you seriously consider at least two Powerwalls - that's 60 amps of power on tap and you'll find 13.5 kWh really isn't all that much - and two Powerwalls will let you run high demand things like Oven/Stoves

3. I would be interested in the cost saving component due to the NEM2 and EV2-A. I can power the house and charge the battery from empty to full before 3PM barring bad weather. If anything, I might even overflow since I get 13kw before 3PM net of my usage. What happen if I generate more, I am assuming I pass it back to the grid without getting anything? This is after my usage too as I only burn about .8kwh during the day 1.2kwh at night. My 14SEER AC and the cars are what kill my electric bill.

Powerwalls can manage this for you by sending 100% of the solar to the grid during peak rates, and only charging the batteries with "cheap" off-peak solar power - however getting an ROI out of Powerwalls is a difficult $$$ proposition - so I recommend you make your decision based on the PW functionality and benefit to your home rather than trying to calculate marginal returns by sending power to the grid for 3 or 4 hours day.

4. Does the battery always default to sending all power to the house before charging or can you change it to not use it? In my scenario, I am hoping to use all solar for home usage as soon as it starts generating. Any excess should go back to the battery (I will likely set it to 10-15% reserve). I should start feeding the battery at about 9AM and the battery should be full by 2 or 3PM. I want to then stop charging the battery and use battery only except when I hit 15%. In the perfect world, that would be 11PM. That would basically shoot my peak electric bill to zero and I am really paying for the car's charging and a few kw I use at night. If I get lucky and have extras, I will drain it overnight and have 2 or 3kw ready for the morning. Rinse and repeat. I guess on rainy days I would be screwed as I would have to buy everything from the grid.

House gets first dibbs on the solar power, the batteries will only charge from solar (either all solar or excess solar). After the batteries are "full" solar goes first to the house and then to the grid.

5, What is the labor cost for one PW2? I already have the panel and their solar.

labor starts at about 2500-4000 for 1 or more PW's - the major cost it he batteries, the gateway, the new sub panel, and the labor (in that order) again I'd recommend more than 1 Powerwalls - the incremental cost barely changes the labor and at least 2 with 60 amps of power and 28 kWh of capacity is a great system and can handle most homes over night.

labor isn't quite as much about number of Powerwalls as it is complexity of integrating your existing electrical system into the Powerwalls.
 
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mattack4000

Active Member
Oct 1, 2017
2,424
952
CA
I don't need new panel, I have plenty of panel space. They can basically create a panel and just run my entire 100A subpanel off it. I am just concern they will have problem with it because there is a 40A EVSE charger on there (something I don't use), I charge my car off a 50A off the main panel.

I should mention it isn't just a NEM1 vs NEM2 problem. Does anyone know if they will kick me off EV-A and onto the stupid EV2-A? I think that's going to be a big determining factor on rather this is a good $ prop or loser. Excluding my usage after midnight (car charging), I am seeing an average of -13kwh going back to the grid daily (sunny 75-80F weather here) and +10kwh between 3PM-12AM. On EV-A, I might save around $1-$1.5 per day. On EV2-A, the savings is closer to $2.50-$3 on average per day by just charging between 8AM-3PM and offload as much as I can from 3PM onward.

Also some have mentioned that PGE has to pay you if you feed extra to the grid as long as you don't charge your battery with their power? That would make the math even better. Am I correct or totally off base?

I checked my feed. If this weekend's weather is any indication, 1 battery should provide what I need.
 

GenSao

Member
Aug 3, 2017
550
938
Pleasant Hill, CA
I don't need new panel, I have plenty of panel space. They can basically create a panel and just run my entire 100A subpanel off it. I am just concern they will have problem with it because there is a 40A EVSE charger on there (something I don't use), I charge my car off a 50A off the main panel.

I should mention it isn't just a NEM1 vs NEM2 problem. Does anyone know if they will kick me off EV-A and onto the stupid EV2-A? I think that's going to be a big determining factor on rather this is a good $ prop or loser. Excluding my usage after midnight (car charging), I am seeing an average of -13kwh going back to the grid daily (sunny 75-80F weather here) and +10kwh between 3PM-12AM. On EV-A, I might save around $1-$1.5 per day. On EV2-A, the savings is closer to $2.50-$3 on average per day by just charging between 8AM-3PM and offload as much as I can from 3PM onward.

Also some have mentioned that PGE has to pay you if you feed extra to the grid as long as you don't charge your battery with their power? That would make the math even better. Am I correct or totally off base?

I checked my feed. If this weekend's weather is any indication, 1 battery should provide what I need.

Assuming the 40A EVSE charge is the only 240V circuit in the 100 A panel, the easiest solution is to move the 40A curcuit breaker to the 200A main panel or remove it entirely.

Regarding staying on the EV-A rate, you have up to five years of EV-A depends how long you have had solar or been on the EV-A rate schedule. Adding Powerwalls or solar will not kick you off the EV-A rate.

Pursuant to D.17-01-006, as revised by D. 17-02-017 and D. 17-10-018, for grandfathered service, certain solar customers will be allowed to continue service on Rate A of this schedule. Specifically, solar customers that interconnected by December 16, 2016, and elected service under Schedule EV prior to July 31, 2017, are allowed to retain service under this schedule for five years after issuance of the permission to operate, but no later than July 31, 2022. In addition, pursuant to D. 16-01-044, net energy metering customers that interconnected after December 15, 2016 and elected service on Rate Option A of this rate schedule may also continue service on this rate schedule for a period of 5 years from the date the customer commenced service on the NEM 2.0 rate, but no later than November 30, 2025. Existing EV-A customers seeking to commence service on NEM2.0 rate and continue service on EV-A for up to 5 years must submit an interconnection application by November 30, 2019.

Furthermore, the PG&E EV FAQ states: "NEM customers are eligible for 5-years of grandfathering based on either their Permission to Operate (PTO) date. Please refer to this table for an example schedule.

NEM1 Transition Examples
  • PTO Date = Grandfathered Until
  • Prior to 11/30/14 = No Grandfathering
  • 12/1/14 - 11/30/15 = November 2020
  • 12/1/15 - 11/30/16 = November 2021
  • 12/1/16 - 11/30/17 = November 2022
NEM 2 Transition Examples
  • NEM 2.0 Active Date = Grandfathered Until
  • 12/16/16 - 11/30/17 = November 2022
  • 12/1/17 - 11/30/18 = November 2023
  • 12/1/18 - 11/30/19 = November 2024
  • 12/1/19 - 10/31/20 = November 2025"
In all cases, you will be eventuality forced to switch to EV2-A. I am not looking forward to the switch. At least the Powerwalls will mitigate the cost of the revised peak times.

I don't believe PG&E will pay you more for power outside of the existing TOU rates. You may be talking about Community Choice Aggregation (CCA) programs. They have different incentives and rates.
 
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dortor4ev

Member
Feb 24, 2013
210
336
San Jose, CA
you will get a new subpanel - Tesla will combine all the “generation/battery” breakers into one common panel for safety and consistency - it’s call the generation load center (anything that can “produce” power” solar & battery) from this panel will be a single circuit that feeds into the Powerwall gateway - that way the gateway can “tap/montior” this source of power for the power routing it needs to perform.

the SOP install is as follows

1. combine the solar sources into the new new generation subpanel
2. add 1 30 amp breaker per-battery to the generation subpanel
3. insert the gateway between the power meter and the whole house subpanel so that the gateway can disconnect you from the grid in the event of a poweroutage
4. now that the gateway is at the center of things it can control the solar inverters and batteries and take over hte power distribution for the home.

it’s very unlikely you will get a powerwall installed with out the basic steps outlined above.
 

dortor4ev

Member
Feb 24, 2013
210
336
San Jose, CA
and yes you will be transitioned on to a “new” NEM plan as part of the appllcation to PG&E - since you are making a change to your solar system and grid connection by adding storage on site PG&E will mandate a new agreement and tranistion you off of your old agreement.

ask me how I know it came as a rude surprise.
 

dortor4ev

Member
Feb 24, 2013
210
336
San Jose, CA
Assuming the 40A EVSE charge is the only 240V circuit in the 100 A panel, the easiest solution is to move the 40A curcuit breaker to the 200A main panel or remove it entirely.

Regarding staying on the EV-A rate, you have up to five years of EV-A depends how long you have had solar or been on the EV-A rate schedule. Adding Powerwalls or solar will not kick you off the EV-A rate.



Furthermore, the PG&E EV FAQ states: "NEM customers are eligible for 5-years of grandfathering based on either their Permission to Operate (PTO) date. Please refer to this table for an example schedule.

NEM1 Transition Examples
  • PTO Date = Grandfathered Until
  • Prior to 11/30/14 = No Grandfathering
  • 12/1/14 - 11/30/15 = November 2020
  • 12/1/15 - 11/30/16 = November 2021
  • 12/1/16 - 11/30/17 = November 2022
NEM 2 Transition Examples
  • NEM 2.0 Active Date = Grandfathered Until
  • 12/16/16 - 11/30/17 = November 2022
  • 12/1/17 - 11/30/18 = November 2023
  • 12/1/18 - 11/30/19 = November 2024
  • 12/1/19 - 10/31/20 = November 2025"
In all cases, you will be eventuality forced to switch to EV2-A. I am not looking forward to the switch. At least the Powerwalls will mitigate the cost of the revised peak times.

I don't believe PG&E will pay you more for power outside of the existing TOU rates. You may be talking about Community Choice Aggregation (CCA) programs. They have different incentives and rates.

getting PG&E to honor these agreements is a night mare - 14 months later and I’m still arguing with them.
 

miimura

Well-Known Member
Aug 21, 2013
6,375
6,079
Los Altos, CA
and yes you will be transitioned on to a “new” NEM plan as part of the appllcation to PG&E - since you are making a change to your solar system and grid connection by adding storage on site PG&E will mandate a new agreement and tranistion you off of your old agreement.

ask me how I know it came as a rude surprise.
PG&E NEM1 Tariff has explicit rules for remaining on that tariff. Just adding battery storage is not sufficient to get you kicked out to NEM2. I am still on NEM1 with my solar installed in 2012 and Powerwall installed in 2018. I did get kicked out of EV-A to EV2-A.
 

mattack4000

Active Member
Oct 1, 2017
2,424
952
CA
It's not that easy to remove the 40A EVSE from the 100A subpanel because the subpanel is on the other side of the garage. All the wires are inside the wall. Ideally their transfer box should contain my two solar and the subpanel and maybe the alarm system. I could in theory just swap the breaker to a 20A and the plug to keep it low. I have put the $99 deposit on one, let's see what the final damage is going to be. I got my permission to operate, luckily still on NEM1 and EV-A. Let's see when they make the switch
 

mattack4000

Active Member
Oct 1, 2017
2,424
952
CA
I spoke too soon. I already got a 8 day bill for NEM2, luckily still EVA. I am seeing net negative for peak and partial peak, mainly usage during off peak hours (car charging).
 

PVRoadster

New Member
May 9, 2019
3
1
Michigan
The Tesla is only eligible for the Tax Credit if it is being charged by the solar only. ThepPower company shouldn't have to be notified as long as you aren't changing inverters, solar panels, or anything else that would impact outflow/generation. in other word, adding a Tesla Power should not affect your net metering/distributed generation agreement. The Powerwall does not send energy back to the grid.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,654
10,899
Riverside Co. CA
The Tesla is only eligible for the Tax Credit if it is being charged by the solar only. ThepPower company shouldn't have to be notified as long as you aren't changing inverters, solar panels, or anything else that would impact outflow/generation. in other word, adding a Tesla Power should not affect your net metering/distributed generation agreement. The Powerwall does not send energy back to the grid.

Adding a powerwall (at least in california) does not effect NEM agreements already in place, but DOES require an amendment to the interconnect agreement with the utility. It has to be noted that you have storage as well as generation onsite with the utilities here. Maybe its different where you are.

In any case, even though it requires a new interconnect agreement, it does not chnage NEM status with the utilities here.. but as I mentioned they DO have to be notified, and permits pulled etc.
 
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