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Adding a Powerwall to existing solar in CA

NarTaX

Member
Mar 27, 2017
29
3
San Jose, CA
I want to get a Powerwall for the purpose of being able to keep the solar panels online while the grid is down. Mainly to be able to charge the car if there's a multi day outage. I'm currently on NEM 2.0 on EV-A with PG&E. Can I still retain my net metering and EV-A plan if I added a Powerwall?
 

miimura

Well-Known Member
Aug 21, 2013
6,362
6,065
Los Altos, CA
I want to get a Powerwall for the purpose of being able to keep the solar panels online while the grid is down. Mainly to be able to charge the car if there's a multi day outage. I'm currently on NEM 2.0 on EV-A with PG&E. Can I still retain my net metering and EV-A plan if I added a Powerwall?
Yes, you can. Installing a Powerwall system will not force a PG&E rate plan change. However, EV-A is going away eventually and your solar PTO date will determine how much grandfathering you will get.
 
  • Informative
Reactions: bmah

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,608
10,843
Riverside Co. CA
I want to get a Powerwall for the purpose of being able to keep the solar panels online while the grid is down. Mainly to be able to charge the car if there's a multi day outage. I'm currently on NEM 2.0 on EV-A with PG&E. Can I still retain my net metering and EV-A plan if I added a Powerwall?

I just placed an order for powerwalls today after doing some research (its the one piece I am missing, have solar city solar, have tesla car, just missing battery). I am on SCE net metering 1.0, so I am happy to hear that it doesnt change rate plans. I believe I will have to move to "some other" plan next year sometime.

OP just a note.... if your main purpose of getting powerwalls is to "charge your car" you might want to consider that each powerwall has 13.5 kW of power when its full, and your car likely has 75-100kW to fill up. You are not likely going to be "filling your car up from your battery".

Even if you are generating a bunch of solar, during an outage you likely want that for your house, not your car.. Easy enough to drive the car to the closest supercharger or other functioning charger, rather than using up 100% of your batteries to fill your car 30%.

At least, thats my thinking and the way I understand it as a hopefully "soon to be" powerwall owner.
 
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Reactions: KSilver2000

miimura

Well-Known Member
Aug 21, 2013
6,362
6,065
Los Altos, CA
In my situation, I actively DON'T want Powerwall energy to go into my EVs. It's cheaper to take the Off-Peak energy from PG&E and if the batteries fill during the day, take the Part-Peak NEM credits. However, with the EV2 rate plan coming, there will be little Part-Peak solar generation any more. :(
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,608
10,843
Riverside Co. CA
In my situation, I actively DON'T want Powerwall energy to go into my EVs. It's cheaper to take the Off-Peak energy from PG&E and if the batteries fill during the day, take the Part-Peak NEM credits. However, with the EV2 rate plan coming, there will be little Part-Peak solar generation any more. :(

Thats what I would want too (for the EV to actively NOT take power from the powerwall. Reading a few threads here, it seems to me that the EV takes power from the powerwall unless you do some time of use scheduling stuff that @MorrisonHiker mentioned around time of use scheduling.

Even if I ask them to put in an essential loads panel (and I was planning on asking for the whole home option instead of that), and not put the car in that panel, it appears to me that the only time the car wouldnt take from the powerwall if plugged in, would be during a power outage, or if you play around with the scheduling.

I am reading a bunch more on powerwalls since I finally decided to jump in and get one to get the 30% credit that is getting reduced this year (and my wife and I deciding that, yes, we likely will be in this home for at least another 10-12 years, maybe longer).

Hoping to learn more from all you powerwall experts here!
 

miimura

Well-Known Member
Aug 21, 2013
6,362
6,065
Los Altos, CA
Thats what I would want too (for the EV to actively NOT take power from the powerwall. Reading a few threads here, it seems to me that the EV takes power from the powerwall unless you do some time of use scheduling stuff that @MorrisonHiker mentioned around time of use scheduling.

Even if I ask them to put in an essential loads panel (and I was planning on asking for the whole home option instead of that), and not put the car in that panel, it appears to me that the only time the car wouldnt take from the powerwall if plugged in, would be during a power outage, or if you play around with the scheduling.

I am reading a bunch more on powerwalls since I finally decided to jump in and get one to get the 30% credit that is getting reduced this year (and my wife and I deciding that, yes, we likely will be in this home for at least another 10-12 years, maybe longer).

Hoping to learn more from all you powerwall experts here!
The settings in the Time Based Control mode are key to controlling when the batteries are charged and discharged. When the grid is up, the Powerwalls can offset any use on any circuit as long as it's configured properly. When the grid is down, only the circuits behind the Gateway will have power.

The Off-Peak discharge shown by @MorrisonHiker is, in my opinion, a result of a deficiency in the TBC algorithm due to their large solar and 4 Powerwall installation. I have a small solar system, so the algorithm is more conservative about when it discharges. However, when my SOC is high after a weekend of Off-Peak generation, my Powerwalls will also discharge some on Monday mornings during Off-Peak.
 

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