We are in Southern California (Orange County) and in the process of the site inspection etc for Powerwall installation. We installed an 11kwh solar system through Tesla last year but have been waiting on the Powerwall due to "supply issues". My question is with the new software and the ability to discharge to augment TOU demand, has anyone in the area actually seen an effect on their monthly bill? I keep trying to justify these power walls from a financial standpoint and can't make a good argument except to have backup power. We have lived in this neighborhood for five years and have maybe had two or three short power surges where things reset but no actual outages.
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Any change in electric bill?
- Thread starter OCdave
- Start date
nwdiver
Well-Known Member
I have a 12kW solar system in Los Angeles County. I was already on SCE TOU-D-A rate before PW installation, and my bill ranged from -$25 to -$50 per month. After PW and operating in TBC, it ranges -$60 to -$80 per month. Not a tremendous amount, but a decrease nevertheless.
roblab
Active Member
I have 11 kW of solar and use the grid for my power balancing, and the power company routinely turns off power for days at a time with no warning, the last time for winds that would be mild zephyrs in Colorado. I am buying power walls simply so that my computers, TV, lights, and heater fan keep working, along with my well pump and septic pump, when the power company decides to turn off power for several hundred square miles. After three days, you don't want to go there, as they say.
Yes, I've seen a significant change in my power bills, but I'm a net consumer, so I can use any extra NEM credits I generate. If you're a net producer, you won't get as much benefit. On a typical summer week day, I can shift about 4-5 kWh of usage from peak to part-peak. On the E-6 rate, that comes out to 46-57.5 cents per day or maybe $10 per month. As you can see payback if you're counting on TOU arbitrage is not really in any kind of reasonable time frame. In addition, I managed to get a few hundred dollars back during the year by doing OhmConnect. I did get the SGIP (Step 3), and I do value the backup functionality, so all in all I'm happy with my purchase, but I definitely don't think you can make a financial argument for getting them unless you assign some value to the backup potential.
Note also that I'm on NEM 1. On NEM 2, you might be able to save a few more pennies a day by doing more self-consumption (to avoid non-bypassable charges).
Shygar
Member
I see a benefit to curtail my peak usage since most of my solar is generated in my part peak time. But it's even more beneficial for me since my total installed price was $7500 for one powerwall 2, minus 30% from the federal tax credit, and minus another $3500 for SGIP. So it really made sense for me and I really wish I got two of them instead of just one, since one is not enough to keep my AC running through my peak hours.
How many EVs do you have? I also have a 12kW solar and so far (5 months since turn on in Aug '18), I have -$520. This is with charging 2 EVs at night (50,000 annual miles combine for 2 cars). I am also on the TOU-D-A rate and no PW. Maybe you charge your cars during the day or use a lot of other electricity during the day?
I have no EV's yet. The amounts were monthly, right now my annual bill is at -$750 and I'm on NEM 1.0. All my heavy usage (pool pump) is at night on the lowest rate, PW covers entire peak, and most of part peak is solar. But it's all play money, SCE won't credit anything other than negative usage. But it shows how the load shifting can greatly reduce bill amount. And that helps during the summer when AC usage can be high.
With the soon to be coming changes in the TOU time periods (shifting from 2-6pm to 4-9pm) there will be greater impact of PW usage by reducing demand during the "duck curve" ramp. I'll see less saving on the bill because the off-peak rates will be so much lower during the day, but I will still be negative which means no monthly bill (besides the minimum charges). And then I can charge an EV anytime other than peak for the same $.012-$0.13 per kWh.
With the soon to be coming changes in the TOU time periods (shifting from 2-6pm to 4-9pm) there will be greater impact of PW usage by reducing demand during the "duck curve" ramp. I'll see less saving on the bill because the off-peak rates will be so much lower during the day, but I will still be negative which means no monthly bill (besides the minimum charges). And then I can charge an EV anytime other than peak for the same $.012-$0.13 per kWh.
That's why I am wondering why you would not have a even more "neg" monthly bill. I have the same size system, I ran my pool pump during the day, I have 2 EVs, my wife stays home so AC is on continuously during the summer. Yet, I have a -$100 bill per month without PW. My annual bill would be at -$1400 by my estimate. Can't get much back so I should have went for a 8kw system I think.
OH wow - I had no idea they are changing the peak times. That will really effect our production:utilization. Thanks for the info
I think you got the order wrong on that computation, it's $7500 for the powerwall 2, minus $3500 for the SGIP, minus 30% of the residual for the ITC, or $2800.
Cheers, Wayne
Shygar
Member
Actually no, I got the 30% off $7500, which is roughly $2250 off (got that last year). All the documents I've signed for SGIP say I'm getting roughly $3500 for Step 4. So I should be getting a total of roughly $5750 off.
I think it would be interesting to get a tax expert's opinion on this. I think that there may be a requirement to amend the tax return if one takes the ITC on the full amount but gets a rebate later. Otherwise, you may have to claim the SGIP amount as income.
I'm in the same position as I'm getting my ITC for TY 2018 and will hopefully get my SGIP payment this year. Everything authoritative I've seen says that the ITC only applies after all rebates are taken, although I know some installers have a more aggressive interpretation of the rules in their marketing literature.
I'm in your area, and supposedly my installer is just now designing my install after a year of waiting on Tesla for supply.
There is NO financial justification for getting the PowerWall to cover TOU (it'll take more than 10 years), and even more time without a decent SGIP rebate.
With 11 kW, you should have no problems covering the TOU period with just the feed-in tariff you get back from SCE. I have 10.1 kW on NEM 2.0, and I already have $9xx credit for the year that I need to burn off.
You're probably in NEM 1.0 so you don't have to worry about NBCs, so worry only about if keeping your solar-system operating during any of the rolling blackouts is worth the PW price.
The ITC only applies to your net cost for your Powerwall after all other rebates. Please read 26 US Code Section 136 (a) and (b). So if you took the ITC on the full Powerwall cost one tax year, and then get an SGIP rebate the following tax year, you will need to repay the excess ITC that second tax year.
Cheers, Wayne
Shygar
Member
I haven't actually gotten my SGIP rebate check, so once I do I'll talk to a tax guy and see what they recommend.
