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Emergency Powerwall Mode

HappyWino

Member
Sep 5, 2019
62
70
NorCal, US
So I'm sitting in my dark garage on day one of a multiday PG&E outage looking at a "60kWh Powerwall on wheels" (Model 3 SR+) that is already connected via a 50A circuit to my home thinking "Tesla has to have all the bits and pieces to make this happen just laying around!!!"

How about it Elon?
 

lemketron

Member
Nov 8, 2013
31
120
Sunnyvale, CA
I'm tempted to hook up a 750W inverter (that I currently have attached to a small Toyota to keep the fridge in the house running) to the 12v Penthouse tonight and see how it works out. If I turn on Standy for Summon then it should stay energized all night right?
This thread suggests that the penthouse connection could be good for 200A... that would imply ~2000W, but I haven’t seen confirmation of anyone trying such a load:
Aux 12V Always On Power Supply | Tesla

But with PG&E blackouts looming, it sure would be nice to be able to use our car as a temporary Powerwall for a ~$300 investment. Actually a LR stores about five powerwalls’ worth of energy!
 

miimura

Well-Known Member
Aug 21, 2013
6,478
6,230
Los Altos, CA
This thread suggests that the penthouse connection could be good for 200A... that would imply ~2000W, but I haven’t seen confirmation of anyone trying such a load:
Aux 12V Always On Power Supply | Tesla

But with PG&E blackouts looming, it sure would be nice to be able to use our car as a temporary Powerwall for a ~$300 investment. Actually a LR stores about five powerwalls’ worth of energy!
Yes, it seems to be consensus that the penthouse terminals are the best place on a Model 3 to take significant amounts of power.

I have used Anderson-type connectors like this one with 4ga welding wire.
https://smile.amazon.com/dp/B007JMTS14/?coliid=IXZXT5M1BUBED&colid=1CDOB7SW5FOVM&psc=1
Also, make sure to get a good quality inverter. I bought this one for my power export from the RAV4 EV.
https://smile.amazon.com/gp/product/B076T8MW4F/ref=ppx_yo_dt_b_asin_title_o09_s01?ie=UTF8&psc=1
 
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ecobra

New Member
Jan 31, 2019
3
0
San Diego, CA
Since before you could by a Roadster there has been Vehicle To Grid standards, discussion, etc. in the industry. Nissan has been saying how stupid power walls are when you already have hundreds of thousands of large energy storage devices.
That said the Tesla is more than capable of becoming a mobile energy storage device through it's supercharging connector. It would require a Tesla charging cable, inverter, and software on both ends. It may be possible to use with with a chademo adapter to use something like OVO Vehicle-to-Grid Charger | OVO Energy but I haven't tried.
 

HappyWino

Member
Sep 5, 2019
62
70
NorCal, US
Just an update, I got on chat with Tesla and after some initial misunderstanding the rep. said yes, it would be fine to hook up an inverter to the 12v battery.

Hooked up a 750W inverter, positive to the positive on the battery, negative to the chassis. Set summon mode to allow Standby at home and plugged in the two fridges.

Ran all night for two nights in a row without issue, battery drain was less than 10% but I have to attribute at least some of that to Standby being on on all for Summon.

Very happy with the result and will do it again in a pinch.
 

ecarfan

Well-Known Member
Sep 21, 2013
19,344
14,010
West Vancouver, British Columbia
So how many AC 120V amps are you producing from the DC 12V battery?
Just an update, I got on chat with Tesla and after some initial misunderstanding the rep. said yes, it would be fine to hook up an inverter to the 12v battery.

Hooked up a 750W inverter, positive to the positive on the battery, negative to the chassis. Set summon mode to allow Standby at home and plugged in the two fridges.

Ran all night for two nights in a row without issue, battery drain was less than 10% but I have to attribute at least some of that to Standby being on on all for Summon.

Very happy with the result and will do it again in a pinch.
 

SageBrush

REJECT Fascism
May 7, 2015
12,499
15,505
New Mexico
Yes, it seems to be consensus that the penthouse terminals are the best place on a Model 3 to take significant amounts of power.

I have used Anderson-type connectors like this one with 4ga welding wire.
https://smile.amazon.com/dp/B007JMTS14/?coliid=IXZXT5M1BUBED&colid=1CDOB7SW5FOVM&psc=1
Also, make sure to get a good quality inverter. I bought this one for my power export from the RAV4 EV.
https://smile.amazon.com/gp/product/B076T8MW4F/ref=ppx_yo_dt_b_asin_title_o09_s01?ie=UTF8&psc=1

Can you attach the inverter to your house panel for the equivalent of a whole-house battery backup ?
Would that risk energizing the grid, and if so could be it be handled by flipping the main panel switch ?
 
Feb 26, 2016
528
501
California
Summon standby! I didnt think of that.

I hooked a 1000w to mine and it ran down the 12v battery so quickly the car never got a chance to charge it back up and I got a low voltage error on the car. Only took about 10 minutes.
 

miimura

Well-Known Member
Aug 21, 2013
6,478
6,230
Los Altos, CA
Can you attach the inverter to your house panel for the equivalent of a whole-house battery backup ?
Would that risk energizing the grid, and if so could be it be handled by flipping the main panel switch ?
My inverter is only 120VAC. In theory, if you wanted to power the circuits in your house this way you could do one of two things:
1. Get an autotransformer and plug in to a 14-50 socket in your garage. When you create an energized plug (not socket), this is commonly called a "Dead man's plug" because it's dangerous.
https://smile.amazon.com/Victron-Energy-Autotransformer-120-240VAC-32A/dp/B01MXI87GZ

2. Wire the 120V output to both hot wires in a 14-50 socket in your garage. Make sure to turn off any 240V double pole breakers in the house because they won't work.

Of course, you would have to turn off your main breaker to make sure you're not back-feeding the grid. You would also have to turn off the breakers for most of the loads that you don't really need so that you don't overload the inverter.

This is NOT RECOMMENDED. I'm just commenting on what would theoretically work in an emergency.
 
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miimura

Well-Known Member
Aug 21, 2013
6,478
6,230
Los Altos, CA
That's only if you get solar + powerwall at same time.
No. You can take the ITC 30% credit on your taxes as long as the batteries are charged 100% from on-site renewable energy. There is an IRS advice letter that stipulated that a Powerwall system installed in a different tax year than a paired solar system is allowed to take the credit.

I have taken the credit for a Powerwall system installed in 2018 and a solar system that was installed in 2012. My tax accountant is very strict and he allowed it. However, the credit amount is only calculated on your net cost after any applicable rebates. I got a large SGIP rebate, so the 30% tax credit was calculated with the SGIP deducted from my up-front cost.
 

crackers8199

Active Member
May 31, 2015
1,285
599
lake elsinore, ca
No. You can take the ITC 30% credit on your taxes as long as the batteries are charged 100% from on-site renewable energy. There is an IRS advice letter that stipulated that a Powerwall system installed in a different tax year than a paired solar system is allowed to take the credit.

I have taken the credit for a Powerwall system installed in 2018 and a solar system that was installed in 2012. My tax accountant is very strict and he allowed it. However, the credit amount is only calculated on your net cost after any applicable rebates. I got a large SGIP rebate, so the 30% tax credit was calculated with the SGIP deducted from my up-front cost.

How did you go about getting the powerwalls with SGIP? I still can't get installers to give me a straight answer on it...
 

miimura

Well-Known Member
Aug 21, 2013
6,478
6,230
Los Altos, CA
How did you go about getting the powerwalls with SGIP? I still can't get installers to give me a straight answer on it...
I placed a deposit with a third party installer before the current round of SGIP opened in May 2017. By doing that, my application went in on the first day that the Step 1 opened and I got the maximum SGIP rebate for the Small Residential Storage class. If I was in the market today and wanted to get a rebate, I would wait and watch what the next round of SGIP will be like. It has already been funded by the State but they need to let this cycle run its course and then decide what if any changes they want to make for the next round. I would expect them to start deciding about the next round in the Spring. If you are seriously in the market now for 3 or more Powerwalls, there is still money available in the Large Storage class.
 

crackers8199

Active Member
May 31, 2015
1,285
599
lake elsinore, ca
I placed a deposit with a third party installer before the current round of SGIP opened in May 2017. By doing that, my application went in on the first day that the Step 1 opened and I got the maximum SGIP rebate for the Small Residential Storage class. If I was in the market today and wanted to get a rebate, I would wait and watch what the next round of SGIP will be like. It has already been funded by the State but they need to let this cycle run its course and then decide what if any changes they want to make for the next round. I would expect them to start deciding about the next round in the Spring. If you are seriously in the market now for 3 or more Powerwalls, there is still money available in the Large Storage class.

i'm looking at one or two, so large storage won't work. i have been trying to figure out if it's doable to get the federal credit + SGIP together...or if not, which one is better to take on its own.

how many powerwalls do you have, and what was your total cost all-in after all credits?
 

miimura

Well-Known Member
Aug 21, 2013
6,478
6,230
Los Altos, CA
i'm looking at one or two, so large storage won't work. i have been trying to figure out if it's doable to get the federal credit + SGIP together...or if not, which one is better to take on its own.

how many powerwalls do you have, and what was your total cost all-in after all credits?
I have two. I think after SGIP and tax credit it was about $6,030 final net cost. There's no way you're going to get anywhere close to that now. AFAIK, if you want one this year with the 30% tax credit your best bet is to go straight with Tesla and take the tax credit. You will still be about $12k net cost for two.
 

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