Tesla PowerWall without Solar with TOU

[TSLRider]

I'm trying to determine the viability of getting 1 or 2 PowerWall's installed given I have no solar to power them and they would have to be grid charged. On the plus side I'm in the most expensive electricity market in the USA being San Diego (SDG&E) and have access to the EV-TOU5 plan which has tremendous delta's in rates being charged from as low as $0.145 at the lowest to as high as $0.816 on peak. So I put together a google sheet EV TOU5 that includes my actual power usage for on/off/super for both Winter and Summer rates. You could simply copy this to your own sheet and adjust the usage numbers to your own and the rates to your rates and it should calculate the rest for you, but it's already SDG&E EV-TOU5.

Based upon this it really does appear to be a very fast payback cycle as a single powerwall should be able to more than shift just winter and summer on to Super Off Peak and 2 powerwalls would be more than enough to shift both On and Off to Super Off. This leads me to believe I'm probably making some type of fundamental mistake, or I just use a ridiculous amount of power (true).

Am I mistaken in my approach as I've generally heard it won't pay for itself for a long time for most people or is it just the unique San Diego market and EV TOU pricing that makes it practical?

 

[sunwarriors]

Another poster here has ran numbers for what you are thinking so maybe they can link to their old post.

What breaks in this calc in my mind is that SDG&E can always raise rates/fees to break this or make this less beneficial. Probably by tacking on higher NBC or more fees to use the grid at all.

They can raise EV-TOU5 off-peak rates as well and also raise the minimum monthly fees to be on the plan.

Overall, TOU is probably here to stay so it will probably still be ok, but one forgets that you have to shell out $25k-$30k for 2 PWs or something for batteries and one shoouldn't forget how bad degradation/if any will be in 10 years.

 

[h2ofun]

Another poster here has ran numbers for what you are thinking so maybe they can link to their old post.

What breaks in this calc in my mind is that SDG&E can always raise rates/fees to break this or make this less beneficial. Probably by tacking on higher NBC or more fees to use the grid at all.

They can raise EV-TOU5 off-peak rates as well and also raise the minimum monthly fees to be on the plan.

Overall, TOU is probably here to stay so it will probably still be ok, but one forgets that you have to shell out $25k-$30k for 2 PWs or something for batteries and one shoouldn't forget how bad degradation/if any will be in 10 years.

I just do not understand why some think they can game the system, and to do it, pay tens of thousands. Makes no logical sense to me.
But as I continue to say, if one has money to burn, and wants to play with this stuff all the time, go for it.

 

[Redhill_qik]

I'm trying to determine the viability of getting 1 or 2 PowerWall's installed given I have no solar to power them and they would have to be grid charged. On the plus side I'm in the most expensive electricity market in the USA being San Diego (SDG&E) and have access to the EV-TOU5 plan which has tremendous delta's in rates being charged from as low as $0.145 at the lowest to as high as $0.816 on peak. So I put together a google sheet EV TOU5 that includes my actual power usage for on/off/super for both Winter and Summer rates. You could simply copy this to your own sheet and adjust the usage numbers to your own and the rates to your rates and it should calculate the rest for you, but it's already SDG&E EV-TOU5.

Based upon this it really does appear to be a very fast payback cycle as a single powerwall should be able to more than shift just winter and summer on to Super Off Peak and 2 powerwalls would be more than enough to shift both On and Off to Super Off. This leads me to believe I'm probably making some type of fundamental mistake, or I just use a ridiculous amount of power (true).

Am I mistaken in my approach as I've generally heard it won't pay for itself for a long time for most people or is it just the unique San Diego market and EV TOU pricing that makes it practical?

Your highest usage is in September with 433 kWh Peak and 512 kWh Off-Peak for a total if 945 kWh. This works out to 31.5 kWh/day and you would need 3 Powerwalls to cover this. You may need 4 Powerwalls as you need to look at your single day peak usage and not the monthly average to get the full savingsor you could go less and not get the full savings.

You calculated the savings of shifting Peak and Off-Peak to Super-Off Peak as $2,412, but this really should be $2,273 as you forgot to include the 90% charging efficiency (need 1.1 kWh to replace 1.0 kWh) and the intrinsic loss per day (0.2kWh*3=0.6kWh).

Three PWs will likely cost you more than $25K, so around 10-12 years which I wouldn't consider this a very fast payback. The Powerwall warranty is for 10 years and with a target capacity of 70%, so your 3 Powerwalls would be at 28.3 kWh and below the average max need of 31.5 kWh. Seems like a wash to me.

 

[TSLRider]

Thank you all for the feedback,

I am wondering why people are using numbers like 20 or 25k for the cost of 2 powerwalls? I'm showing ordering online directly from Tesla at Powerwall Direct | Tesla the cash price being $18,749 including Tax/Shipping including the gateway and then the 30% federal tax credit takes that down to a much more reasonable $13,124. There is also the possibility of a SGIP if you can find an installer with room in their cap of approx $1750 for each as well. I could also net back another $500 or so in credits from the credit card used of course taking it down to 12.6k if no sgip or even $9k if SGIP (but would have to pay for install if going this route)

Is that what the old pricing was before Tesla opened up ordered directly again just a few weeks ago?

It's also a relatively simple install at least in my house since the location where the breaker box is situated right near where the gateway and powerwalls would be, and shouldn't be too pricey (can even be done yourself if comfortable with it).

Great correction Redhill_qik with the 90% efficiency and loss though, that is a big difference and important to consider along with the degradation as mentioned in the battery capacity. I can try to model those numbers into the sheet to get a better perspective - at least the 10% loss is easy, not sure about the degradation. That particular month you were looking at was during the worst heatwave San Diego has experienced to date, I'm hoping that doesn't become a regular occurrence.

For me if I could get the payback cycle down to something in the neighborhood of 5-7 years I'd consider that very feasible. I'd agree that taking 10 years would be far too long. So I'll keep crunching based upon the numbers and changes provided here to evaluate that position. As mentioned above though of course I am dependent on SDG&E not changing the TOU programs.

 

[jjrandorin]

I am wondering why people are using numbers like 20 or 25k for the cost of 2 powerwalls?

Because its going to cost you around 4-7k labor to get someone to install them. If you get that far down the road of considering this, you will likely find that to be the case.

 

[sunwarriors]

I think it's also good to quote prices before any tax incentives as that's how it's been done I've noticed historically. Some retirees have little/no tax liability so quoting after tax prices makes one feel better or to convince the spouse that it's cheap, but isn't guaranteed if one doesn't have tax liability or it'll take so long to get back.

It's what's out of pocket at the time of payment so one still has to have that sitting around. As for SGIP, good luck. As I've mentioned long ago, a lot of installers have no/0/zero clue how to deal with it and it's a headache.

If you buy 2 PWs for $18-$19k, most installers won't bother unless the labor is worth their time because doing a solar job is simply easier. They don't care how easy you may claim it will be.

Bottom line I still point back to is if you need some ROI to convince yourself, don't bother and keep your powder/cash dry. Do it if you want for power outage protection, tell the IOU to bugger off, but I really feel people overthink this when that introduce ROI in it.

You can also consider other ESS alternatives which I feel has always been better than Tesla PWs. LFP alone which I think Tesla may offer eventually is a no brainer IMO, but as all my posts state, I've pretty biased that Tesla isn't the only game in town for Solar. V2G will be here for Enphase I'd bet for sure and generator support is already live. I paid about the same for Enphase vs. Tesla PWs from 3rd party installers so no need to limit oneself purely from a $$ perspective (though the PWs have higher capacity).

 

[h2ofun]

Because its going to cost you around 4-7k labor to get someone to install them. If you get that far down the road of considering this, you will likely find that to be the case.

Cost me 31K for 2 installed

 

[GregBallantyne]

Because its going to cost you around 4-7k labor to get someone to install them. If you get that far down the road of considering this, you will likely find that to be the case.

Actually.... the 3 I just got installed were $45k installed. The price each didn't vary.... I think that turns out to be about $7k installation each, and there was no discount after the first for lesser install requirements, as I thought there might have been.

 

[TSLRider]

I just wanted to update my post since it's been a while. In my digging I found out that we actually qualify for that California SGIP Equity Resilience Program due to fire zone location and a secondary qualification. I just signed paperwork for an installer to install 2x Powerwalls for just about $30,500 (it was difficult to find one that would work in condo's without solar), however under the equity resilience program my actual out of pocket costs for the 2 Powerwalls will be about $1,800. SDG&E is unable to provide 15 minute usage data which might have qualified me for 3x Powerwalls, but the hour usage data only provided justification for 2. The installer will process the SGIP program and has been 100% successful in their use of it to date. I'll update the post again once they are installed and how long Equity Resilience takes to pay me.

 

[Miata Head]

Almost a MW a month in usage seems insane to me. But I don't have a pool. Do you have a pool? Or is the A/C always on and you're in Escondido or something?

 

[jjrandorin]

I am wondering why people are using numbers like 20 or 25k for the cost of 2 powerwalls?

Because its going to cost you around 4-7k labor to get someone to install them. If you get that far down the road of considering this, you will likely find that to be the case.

I just signed paperwork for an installer to install 2x Powerwalls for just about $30,500

SGIP equity and resiliency notwithstanding, it appears you confirmed what I posted in answer of your question of "why is everyone quoting 20-25k for install?"

 

[TSLRider]

SGIP equity and resiliency notwithstanding, it appears you confirmed what I posted in answer of your question of "why is everyone quoting 20-25k for install?"

Oh I found places willing to do it for much less and you were free to purchase them yourself, but they can't process SGIP which is the problem for me once I realized that component. Otherwise I could have done it for around 5k in labor plus the purchase directly from Tesla.

 

[TSLRider]

Almost a MW a month in usage seems insane to me. But I don't have a pool. Do you have a pool? Or is the A/C always on and you're in Escondido or something?

No pool - but just outside Poway, summers do get very hot for sure.

 

[veganjoe]

No pool - but just outside Poway, summers do get very hot for sure.

So, it's been several months; how goes the energy arbitrage?

 

[TSLRider]

So, it's been several months; how goes the energy arbitrage?

Actually amazingly well - saving literally hundreds of dollars a month. It went so well I went ahead and moved the gas hot water heater to a heat pump in December to save an additional approx $50 in gas cost by shifting that entirely to super-off peak instead.

Here is some data, you can see it was installed mid September and by October I'm using absolutely zero on-peak usage and very little off peak. It enabled my house to shift almost entirely to super-off peak usage. Which on SDG&E is not a joke delta wise see: Electric Vehicle Pricing Plans | San Diego Gas & Electric for EV-TOU5 since it's literally a 4x multiplier.

Tesla VPP program also started in San Diego which assuming I can get admitted would add substantial more savings since I can get up to $2 per kwh selling back to them from a 12.4 cent cost (currently). I do think this arbitrage can potentially make sense for people that have that type of delta. Of course unknowns would be income based billing should it happen, which could mean anyone with solar/batteries has lost their savings, not just me.