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Powerwall: To Get or Not To Get

dandrewk

Active Member
Supporting Member
Jun 25, 2019
1,278
1,009
Marin County, CA
1. It gives you power when your home loses power from the grid. This has taken more relevance lately in light of USA utilities adopting more proactive policies regarding grid shutdowns during wildfire season. The PW works like a whole-house UPS. If the power goes out, you won't know it unless you look at the app (or your neighbor's dark homes. ;) )

2. You will probably soon be on a TOU (time of use) rate tier with your utility, if you aren't already. With PWs, you won't have to worry about not using power hungry devices (EV charging, A/C, laundry etc.) during the day when rates are way higher.

3. During a power outage, you won't lose any solar production. Without PWs, your solar panels shut down when the grid goes down.

BTW, is the $4500 labor costs? Each wall has a list price of $6700.
 
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Reactions: Daskid

Daskid

Member
Jan 5, 2019
127
25
Inland Empire
1. It gives you power when your home loses power from the grid. This has taken more relevance lately in light of USA utilities adopting more proactive policies regarding grid shutdowns during wildfire season. The PW works like a whole-house UPS. If the power goes out, you won't know it unless you look at the app (or your neighbor's dark homes. ;) )

2. You will probably soon be on a TOU (time of use) rate tier with your utility, if you aren't already. With PWs, you won't have to worry about not using power hungry devices (EV charging, A/C, laundry etc.) during the day when rates are way higher.

3. During a power outage, you won't lose any solar production. Without PWs, your solar panels shut down when the grid goes down.

BTW, is the $4500 labor costs? Each wall has a list price of $6700.

Thanks for the information! The $4500 cost is approximate labor cost for installing 2 PW’s as I am told.

I also am under TOU-D-A plan with Southern California Edison. The rep told me that once my solar panels go live, I will be switched to TOU-PRIME automatically. Don’t know if that is true or not. I do want to stay in the TOU-D-A plan though.
 

GenSao

Member
Aug 3, 2017
585
1,016
Pleasant Hill, CA
As an investment, it's not worth it. But if you need backup power and want to be able to use your solar and charge your cars during a grid outage, it's a cool thing to have.

It is not worth it an investment if you excluding the backup power component.

The battery backup portion is worth a couple thousand dollars for the equivalent diesel system with the fuel and maintenance required. If factored in, then I think it can be worth it. Especially if you are on an EV TOU schedule and can take advantage by making some extra money with demand response programs.

As a reminder, the cost of the PW with installation does qualify for the 30% federal tax credit (set to go down after 2019).
 
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NuShrike

Member
Nov 13, 2017
462
197
SoCal
Thanks for the information! The $4500 cost is approximate labor cost for installing 2 PW’s as I am told.

I also am under TOU-D-A plan with Southern California Edison. The rep told me that once my solar panels go live, I will be switched to TOU-PRIME automatically. Don’t know if that is true or not. I do want to stay in the TOU-D-A plan though.
Switched in late 2020, if you're NEM-2.0. Existing TOU-D-A foks are grandfathered until then. NEM-1.0 people are not affected. SCE isn't clear where the cut-off is.

Are you installing a lot of kW that's putting you over some limit? That should at worse only switch you from NEM-1.0 to 2.0, not switch TOU plan on you.

PWs, not worth it unless you're getting a huge rebate, or you'll be heavily hurt by the TOU-PRIME rate.
 

RoBoRaT

Zero Farts Given!
Nov 22, 2018
1,562
1,423
NorthSoCal
Switched in late 2020, if you're NEM-2.0. Existing TOU-D-A foks are grandfathered until then. NEM-1.0 people are not affected. SCE isn't clear where .
Switched in late 2020, if you're NEM-2.0. Existing TOU-D-A foks are grandfathered until then. NEM-1.0 people are not affected. SCE isn't clear where the cut-off is.

We missed the boat, March 2019 was the cut-off...

Screenshot_20190703-163413_Samsung Internet.jpg
 

commasign

TeslaAdviceBlog.com
Aug 31, 2013
3,202
4,292
Davis, CA
It is not worth it an investment if you excluding the backup power component.

The battery backup portion is worth a couple thousand dollars for the equivalent diesel system with the fuel and maintenance required. If factored in, then I think it can be worth it. Especially if you are on an EV TOU schedule and can take advantage by making some extra money with demand response programs.

As a reminder, the cost of the PW with installation does qualify for the 30% federal tax credit (set to go down after 2019).

True. A good value in that case.
 
Has there been a debate regarding if a powerwall is worth getting?

Tesla is recommending me an 8kW system with 2 powerwalls. From my understanding, I would have to issue a check for about $4,500 to get the powerwalls installed.

What does "worth getting" mean to you? The quotes I've seen on this forum for 2 PWs are generally $18-22k installed. The $4,500 figure you mention is just the labor cost -- you're looking at $13-18k more for the PWs and associated equipment. I'm saying this just to make sure you aren't under the impression 2 PWs are only $4,500 because that is not the case.

As others mentioned, you can knock 30% off but even if you take the low-end cost range, you're still talking bout $12,500 after the federal incentive. I don't know if there are still SGIP incentives in your area, so maybe that could knock a few grand more off but my understanding is that those funds are largely unavailable at this point.

You can probably save a few hundred bucks a year in electricity cost with the PWs via "arbitrage" (basically charging PWs from your non-peak solar energy and then consuming from the PWs during peak power so your solar generation can be sold back to the grid)...but it really depends on your setup and again, it's probably only going to amount to a couple hundred bucks a year if you are lucky.

So...is whole house backup worth $8-12k to you? I think most of us love having them and generally think they are awesome...but the "worth it" question seems to depend on each person's personal circumstances.
 

reddy

Active Member
Jan 26, 2013
1,022
1,636
Amarillo, TX
Here's my scenario:

Electric utility (Xcel Energy) in the stone age : I get a 2.3c / kWh credit for any power supplied to Xcel, plus they charge $20 a month to do the accounting. No net metering.

18kWh solar system on large house, 4 powerwalls.

In spring months before AC is needed, I can go weeks with no purchases of power from Xcel. My bill for May/June was $18, most of it for 'service availability', taxes, and fees. About $3 for actual electricity.

In March, we had a massive 'bomb cyclone' that took out power lines for 100 miles in every direction. Power crews worked frantically to get power restored, but we had no grid power for almost 31 hours. I live in a city of about 200,000 , it's not like we live in the boonies.

The solar + powerwalls completely maintained my house for the entire 31 hours. I was the only house in the neighborhood with lights, natural gas heating, electric cooking, freezers, computers still going, etc.

I am getting the investment back on the net metering side. I now give away very little power to Xcel. So little that I canceled the $20 charge every month.

How much the UPS function is worth is debatable. I probably would not have lost much actual money from the power loss, but the freedom from disruption is worth something. As is the satisfaction that I'm living off my solar 24/7 in the spring and fall. Once summer AC season starts, I need more kWh than my panels produce, but I still am getting a lower utility bill by a significant amount.
 
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reddy

Active Member
Jan 26, 2013
1,022
1,636
Amarillo, TX
@reddy are you saying that if you forego the 2.3c / kWh feed in credit, you can also skip the $20 monthly fee? That sounds like a great trade-off in your case.

Yes, I give up the 2.3c credit, but don't get charged the $20. Now that I have powerwalls, I don't sell enough juice to Xcel to amount to $20 in any month. I keep most of it for myself.
 

Daskid

Member
Jan 5, 2019
127
25
Inland Empire
As an investment, it's not worth it. But if you need backup power and want to be able to use your solar and charge your cars during a grid outage, it's a cool thing to have.

I currently do not foresee any power outage in my area. I've only had 1 power outage in the 5 years I lived here. The rep did say that the power company will increase the frequency of these outages. I don't know if she was telling the truth or not. So relying on the PW as backup power is not a main concern. Thanks for your input!

Switched in late 2020, if you're NEM-2.0. Existing TOU-D-A foks are grandfathered until then. NEM-1.0 people are not affected. SCE isn't clear where the cut-off is.

Are you installing a lot of kW that's putting you over some limit? That should at worse only switch you from NEM-1.0 to 2.0, not switch TOU plan on you.

PWs, not worth it unless you're getting a huge rebate, or you'll be heavily hurt by the TOU-PRIME rate.

I'm not sure which NEM tier I'm at with TOU-D-A. I switched from residential tier to the TOU plan in January 2019. How do you find out which NEM tier?
Also heard news that the funds for the SGIP rebate in California is put on hold.

Thanks, that helps. Mar-2019 was when all the former TOU plans got suddenly retired.

But Daskid says already on TOU-D-A PRE-solar, so there's some missing info to connect this all.

I switched from residential tier to the TOU-D-A plan in January 2019 and I have no solar.

What does "worth getting" mean to you? The quotes I've seen on this forum for 2 PWs are generally $18-22k installed. The $4,500 figure you mention is just the labor cost -- you're looking at $13-18k more for the PWs and associated equipment. I'm saying this just to make sure you aren't under the impression 2 PWs are only $4,500 because that is not the case.

As others mentioned, you can knock 30% off but even if you take the low-end cost range, you're still talking bout $12,500 after the federal incentive. I don't know if there are still SGIP incentives in your area, so maybe that could knock a few grand more off but my understanding is that those funds are largely unavailable at this point.

You can probably save a few hundred bucks a year in electricity cost with the PWs via "arbitrage" (basically charging PWs from your non-peak solar energy and then consuming from the PWs during peak power so your solar generation can be sold back to the grid)...but it really depends on your setup and again, it's probably only going to amount to a couple hundred bucks a year if you are lucky.

So...is whole house backup worth $8-12k to you? I think most of us love having them and generally think they are awesome...but the "worth it" question seems to depend on each person's personal circumstances.

Yes, I understand that the $4500 cost is just the labor. I think each PW is around $8000. So you are right, about $20k installed. Backing up my whole house for $8-12k is not worth to me. I'm more concerned about the energy consumption when the sunlight goes out as I plan to be mildly non-conservative on my energy usage.

Here's my scenario:

Electric utility (Xcel Energy) in the stone age : I get a 2.3c / kWh credit for any power supplied to Xcel, plus they charge $20 a month to do the accounting. No net metering.

18kWh solar system on large house, 4 powerwalls.

In spring months before AC is needed, I can go weeks with no purchases of power from Xcel. My bill for May/June was $18, most of it for 'service availability', taxes, and fees. About $3 for actual electricity.

In March, we had a massive 'bomb cyclone' that took out power lines for 100 miles in every direction. Power crews worked frantically to get power restored, but we had no grid power for almost 31 hours. I live in a city of about 200,000 , it's not like we live in the boonies.

The solar + powerwalls completely maintained my house for the entire 31 hours. I was the only house in the neighborhood with lights, natural gas heating, electric cooking, freezers, computers still going, etc.

I am getting the investment back on the net metering side. I now give away very little power to Xcel. So little that I canceled the $20 charge every month.

How much the UPS function is worth is debatable. I probably would not have lost much actual money from the power loss, but the freedom from disruption is worth something. As is the satisfaction that I'm living off my solar 24/7 in the spring and fall. Once summer AC season starts, I need more kWh than my panels produce, but I still am getting a lower utility bill by a significant amount.

Wow 4 PW's at 18kWh. My consumption is at 10.4kWh from July 2018 thru June 2019 being on the conservative side. I started charging at home in January 2019. So I'm thinking my energy consumption for 2019 is around 15kWh. I do want 100% offset but we'll see what the rep recommends. Thanks!

Some utilities are adopting a "virtual power plant" program though perhaps just in NE so far. Adds a bit of payback if you have solar with powerwalls.

Not heard of this program in southern California. I'll have to ask my rep. Thanks!
 

NuShrike

Member
Nov 13, 2017
462
197
SoCal
I'm not sure which NEM tier I'm at with TOU-D-A. I switched from residential tier to the TOU plan in January 2019. How do you find out which NEM tier?
Also heard news that the funds for the SGIP rebate in California is put on hold.
Since you didn't go solar yet, you're be entered into NEM-2.0.

As for being pushed off TOU-D-A, I would get a 2nd and 3rd referral confirmation either directly from SCE.

I've had to go around my installers sometimes because they would spew unchecked BS.
 
I currently do not foresee any power outage in my area. I've only had 1 power outage in the 5 years I lived here. The rep did say that the power company will increase the frequency of these outages. I don't know if she was telling the truth or not. So relying on the PW as backup power is not a main concern. Thanks for your input!

If you're not concerned with power outages, power walls make no sense at all. If you are concerned, they're a hell of an investment.
 

Daskid

Member
Jan 5, 2019
127
25
Inland Empire
Since you didn't go solar yet, you're be entered into NEM-2.0.

As for being pushed off TOU-D-A, I would get a 2nd and 3rd referral confirmation either directly from SCE.

I've had to go around my installers sometimes because they would spew unchecked BS.

Great advise! Will call SCE tomorrow. Thanks!

If you're not concerned with power outages, power walls make no sense at all. If you are concerned, they're a hell of an investment.

Makes sense. Thank you!
 

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