"Free" Power from my Electric Company. Will a PowerWall be worth it?

[SadPanda]

Hi Everyone,

xPosting this from reddit. There is a new power plan from my electric company that features the following rates:

• Super Off-Peak (12 a.m. – 6 a.m.)
  • First 400 kWh: FREE
  • Over 400 kWh: $.0450 per kWh
• Off-Peak (6 a.m. – 1 p.m.) and (9 p.m. – 12 a.m.)
  • $.07181 per kWh
• On-Peak (1 p.m. – 9 p.m.)
  • $.1350 per kWh
• You are allotted up to 400 kWh free per billing cycle during the Super Off-Peak period only. Any consumption over 400 kWh is billed at $.0450 per kWh

So given this scenario, would it be worth it for me to get a powerwall? My power bills are usually over 100, sometimes high 100s.

My monthly meter stats are listed below in kWh.

High Usage:
1,574
Low Usage:
1,178
Average Usage:
1,378

Daily
High Usage:
4.44
Low Usage:
0.85
Average Usage:
2.92
Total Usage:
72.91

Obviously I'm not going to buy one of these things outright. Any decent finance/lease deals that makes sense for me?

 

[JasJ]

Assuming a PW is now $10K installed, you need to offset 74,000 kwH at the peak rate (best case). That's about 153 months of time-shifting the free energy quota (400 per month). So 13 years. This assumes the plan lasts that long and you get a free loan or similar. There is some additional benefit of shifting the low rate to the high rate period but you will need more than one powerwall to do so given your average daily use and that doubles/triples the payback window.


My $0.02

 

[NuShrike]

My monthly meter stats are listed below in kWh.

High Usage:
1,574
Low Usage:
1,178
Average Usage:
1,378

Daily
High Usage:
4.44
Low Usage:
0.85
Average Usage:
2.92
Total Usage:
72.91

Obviously I'm not going to buy one of these things outright. Any decent finance/lease deals that makes sense for me?

My 2c, is you'll probably get more payback if you figure out ways to first somehow cut your baseline usage. Daily use of 72.91 kWh swamps any savings you can get from one PW. You may need up to 4 PWs just to cover normal usage in a power-outage.

Maybe some smart-plugs that can push usage of certain discretionary devices more toward off-peak times. One of the TOU rates here actually allow unlimited off-peak usage, for instance.

 

[cwied]

If you're not shaded, it sounds like solar would be a much better investment than a Powerwall. That should pay back much more quickly than a Powerwall would. It's currently still hard to financially justify a Powerwall even with high California electricity rates unless you get an incentive from your state.

 

[JasJ]

and if you do a powerwall with solar, then the 30% federal tax credit kicks in for not only solar, but the PW as well. Makes the payback better.

 

[miimura]

Drive an electric car and only charge it from midnight to 6am. That will use up your 400kWh/mo and you won't have to buy gas any more. It's a bigger savings than a Powerwall.

 

[gilscales]

Hi Everyone,

xPosting this from reddit. There is a new power plan from my electric company that features the following rates:

• Super Off-Peak (12 a.m. – 6 a.m.)
  • First 400 kWh: FREE
  • Over 400 kWh: $.0450 per kWh
• Off-Peak (6 a.m. – 1 p.m.) and (9 p.m. – 12 a.m.)
  • $.07181 per kWh
• On-Peak (1 p.m. – 9 p.m.)
  • $.1350 per kWh
• You are allotted up to 400 kWh free per billing cycle during the Super Off-Peak period only. Any consumption over 400 kWh is billed at $.0450 per kWh

So given this scenario, would it be worth it for me to get a powerwall? My power bills are usually over 100, sometimes high 100s.

My monthly meter stats are listed below in kWh.

High Usage:
1,574
Low Usage:
1,178
Average Usage:
1,378



Daily
High Usage:
4.44
Low Usage:
0.85
Average Usage:
2.92
Total Usage:
72.91

Obviously I'm not going to buy one of these things outright. Any decent finance/lease deals that makes sense for me?

This is the cheapest electricity rates I have seen!
I'm with SCE and get a pretty good rate on TOU-D-B since I use an average of over 2,000 kWh monthly, still my best rate is .12

Time-Of-Use Residential Rate Plans | Rates | Your Home | Home - SCE

My brother who lives a few minutes from Oroville lake where quite a bit of power is generated is averaging almost twice my rate

 

[Shygar]

Is your grid stable? There could be other benefits besides offsetting your peak usage with a powerwall. But yea as mentioned with rates that cheap your best bet is to get an electric car and drive that, but I know gas is cheaper in the south too.

Your peak rates are my super offpeak rates

 

[ewoodrick]

To determine if it is worth it, you would want to compare it to your existing plan and other offers. Also, be aware that "Free" doesn't necessarily mean free, there are probably some base charges on the bill.
But, using 73 kWh per month, that's just under $10 in usage per month. But I dare say that your bill is more.

So, at $7000, it's going to take 70 months+ to break even.

You really need to look closer at your bill and usage, something tells me that you may be missing something.

 

[ahkahn]

To determine if it is worth it, you would want to compare it to your existing plan and other offers. Also, be aware that "Free" doesn't necessarily mean free, there are probably some base charges on the bill.
But, using 73 kWh per month, that's just under $10 in usage per month. But I dare say that your bill is more.

So, at $7000, it's going to take 70 months+ to break even.

You really need to look closer at your bill and usage, something tells me that you may be missing something.

You're exactly right. Most likely while the electricity itself is free, the distribution costs are still billed. So, all in, you're still paying roughly .03-.05/kWh even if it's free.

 

[SadPanda]

Drive an electric car and only charge it from midnight to 6am. That will use up your 400kWh/mo and you won't have to buy gas any more. It's a bigger savings than a Powerwall.

It looks that would be the best option. Neighbor a few blocks down has a model s and x. Guess they're reaping the benefits already. Might look into getting a used leaf, my car loves to drink gas haha.

This is the cheapest electricity rates I have seen!
I'm with SCE and get a pretty good rate on TOU-D-B since I use an average of over 2,000 kWh monthly, still my best rate is .12

Time-Of-Use Residential Rate Plans | Rates | Your Home | Home - SCE

My brother who lives a few minutes from Oroville lake where quite a bit of power is generated is averaging almost twice my rate

Is your grid stable? There could be other benefits besides offsetting your peak usage with a powerwall. But yea as mentioned with rates that cheap your best bet is to get an electric car and drive that, but I know gas is cheaper in the south too.

Your peak rates are my super offpeak rates

These rates are actually higher than what I'm use to. Before I moved to my current address, I was use to a "normal" plan without peak charges that was lower than the off peak pricing you guys see. Sadly I'm with a EMC now and they love forcing folks with "smart" plans that punish you using electric when you need to. On the upside, somehow despite having wires above ground, I have far far less outages than before, so hey the $ is being put into good use I guess.

You're exactly right. Most likely while the electricity itself is free, the distribution costs are still billed. So, all in, you're still paying roughly .03-.05/kWh even if it's free.

Of course, I understand that "free" here only means the metered use, not the service charges and what not.

 

[Shygar]

The whole point of why utilities prefer the time of use rates is because that's when the electricity costs the most for them to produce traditionally. They're not trying to punish you because you're using electricity when you need it, they're charging you the market cost of that electricity when you and everyone else needs it (after they get home from work and before bed). This is why you charge electric cars at night as the power plants just idle since no one is using power intensive things.

 

[ahkahn]

Of course, I understand that "free" here only means the metered use, not the service charges and what not.

Just to clarify for others that may see this in the future, the distribution costs are ALSO meter billed. Other fees are typically flat, but distribution costs are metered and will vary based on usage. So, for instance, when you're on variable-rate billing, the breakdown is as follows:

Electricity costs: $0.00/kWh (variable)
Distribution costs: $0.04/kWh (typically fixed/kWh)
Taxes: (if applicable, variable based on total charged above)
Account Fees/Meter charges/Etc: flat charges (typically fixed/account)

Hopefully that clears up any confusion.

 

[miimura]

Just to clarify for others that may see this in the future, the distribution costs are ALSO meter billed. Other fees are typically flat, but distribution costs are metered and will vary based on usage. So, for instance, when you're on variable-rate billing, the breakdown is as follows:

Electricity costs: $0.00/kWh (variable)
Distribution costs: $0.04/kWh (typically fixed/kWh)
Taxes: (if applicable, variable based on total charged above)
Account Fees/Meter charges/Etc: flat charges (typically fixed/account)

Hopefully that clears up any confusion.

In Texas there is so much surplus wind power that they really do have free power overnight, even including distribution costs.

 

[2012MS85]

With utility rates this cheap (down to free electricity that could run an EV for your local commute), there is simply no way to ever economically pay for the cost of any battery storage, much less several thousand for a PW2. Where do you live (county and state)? More importantly, what utility offers these great electric rates?

 

[2012MS85]

And when I say Powerwalls are "economic," that is really only true when the "spread" of between your local utility's peak electricity rate (e.g., $0.30/kWh) and off-peak rate (e.g., $0.10/kWh) is about 20 cents, assuming you have Time-Of-Use (TOU) rates. I posted yesterday that most people nod off when I get too detailed with math, so I'm going to give the following break-even analysis only for those numbers geeks who understand and care (everyone else, just remember you need about a $0.20/kWh spread between your time-of-use rates before the Powerwall 2 (PW2) is cost justified for you, if saving money is your ONLY criteria). Let's assume the following:
1. Fully installed cost of PW2 is $8,000 (i.e., $5,500 PW2, $700 Gateway, $1,000 installation, $200 permit, $600 sales tax).
2. 11 kWh of energy are stored every day, on average, for the 10-year warranty life, then the PW2 dies. While you may benefit from a longer life, you also are going to have rainy, snowy, winter days where you can't charge much, so let's call that a wash. Also, Tesla's warranty is for 70% of the 13.2 kWh by year ten, so I'm using a simple linear average of 11 kWh [13.2 + (70% x 13.2)/2].
3. $8,000 full cost, divided by 10-yr useful life, means your cost (assuming you have cash and no better opportunity cost to invest your eight grand cause you're waiting for a stock market crash and your bank pays a lousy 0.1% interest) per year is $800. So you need to divide by 365 days to compute a $2.19 "daily cost" of your PW2. Now divide $2.19 by the average of 11 kWh that you'll charge each day (preferably with your solar, otherwise off-peak TOU cheap electricity) and discharge during peak time (offsetting the limited and expensive resource known as peak electricity). $2.19 / 11 = 19.9 cents.
4. For simplicity, I've ignored that you're going to have efficiency losses when you move all those electrons around (e.g., DC solar to AC PW2, etc.). Depending on your situation, this may average round-trip efficiency loss of 10% or so. So that would bump your 20 cent break even up to $0.22/kWh. So now open your next utility bill and see if you have a 20-22 cent spread on your time of use rates?

Here's a post on the economics of PW2 from a year and a a half ago. Long story short, PW2 only makes economic sense (at the fully installed price, with a 10-year warranty/payback) if you highest peak rate vs your cheapest off-peak rate has at least a 20 cent/kWh spread. Most west coast and east cost (big city) utility rates are high and can justify PW2, once you factor in government rebates/tax credits. Most utility rates in non-coastal areas of the US are too inexpensive to cost justify PW2. Rates are simply too cheap to ever pay off this large upfront investment. That said, there's always the "cool factor" and potential for using PW2 for your backup power if you have frequent power outages

 

[SadPanda]

The whole point of why utilities prefer the time of use rates is because that's when the electricity costs the most for them to produce traditionally. They're not trying to punish you because you're using electricity when you need it, they're charging you the market cost of that electricity when you and everyone else needs it (after they get home from work and before bed). This is why you charge electric cars at night as the power plants just idle since no one is using power intensive things.

I can see the logic, but I'd much rather it be a fixed rate, period like we've always had it. Most of them are grandfathered at this point :/

With utility rates this cheap (down to free electricity that could run an EV for your local commute), there is simply no way to ever economically pay for the cost of any battery storage, much less several thousand for a PW2. Where do you live (county and state)? More importantly, what utility offers these great electric rates?

I guess cheapness is a matter of perspective. I'm in GA. The EMC I'm with has higher rates than GA power actually.

 

[SadPanda]

Hmm no edit button?

Looks like I should look into getting an electric car in the future. I wonder if the used leaf market will get even lower, hmmm... Shame only the newest ones have adaptive cruise control lol. Would be perfect for lazy commuting.

 

[mspohr]

I think it's difficult in most situations to have a Powerwall "pay for itself". It requires TOU with very high peak charges and very low off peak charges and solar. Even then, it's a long time to pay back the cost. (My personal situation is that our local electric utility, Liberty Utilities, oddly mandates that you cannot have TOU with solar net metering.)
However, I am looking at the Powerwall primarily as backup for grid failure. This is something that it difficult to cost so I am not even attempting to do that. Many homeowners in my area have installed backup whole house generators ($10k - $15k) which have no "return" on investment except the peace of mind that they will have power in the event of a grid failure.
My particular situation is that I have fairly reliable grid power but live in the mountains and we do get ferocious storms which damage power lines and can take days or weeks to repair. Lately, the power companies have been shutting down the grid when there is a wind/storm threat to the power lines. They do this to prevent fires caused by downed power lines. Last month they shut down the grid in parts of Northern California when high winds were forecast. Some areas were without power for 3-4 days due to downed lines (but no fires).
The Tesla Powerwall(s) coupled with my solar panels should be able to provide reliable power continuously even during a prolonged grid outage.

So, long story short, I do not expect the Powerwall to "pay for itself" through electricity savings but I do expect the peace of mind and the actual experience of having reliable power during storms, wind, fires, etc. to be worth the cost.

 

[miimura]

Yes, I mentally subtracted the $5k I had budgeted for a nat-gas backup generator when I was deciding on whether to go ahead with my Powerwall installation. Even with the SGIP rebate, I had to allocate some value to the backup power to justify it. We have had 2 hours and 45 minutes of outages across 4 events since the middle of August. There were no outages from when we first got the system installed in the beginning of March to the middle of August. Because we have so many trees in our neighborhood and all overhead power distribution, we have a 4 hour to 12 hour outage almost every year and sometimes a couple times per year.