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Is Powerwall necessary in Bay Area?

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Hi All,

I am looking to install a 6.4kW system in Bay Area, CA, USA. I currently have electricity service from pg&e. While I am trying to read as many as articles as I can get my eyes on to understand if I need a powerwall for my setup, I am unable to conclude either way. In my 15+ years in bay area, I only had a couple of short outages, so with that historical data (ofcourse it doesn't predict the future), I don't see a need for power backup. However, I am not perfectly clear how net metering works with pg&e. I am assuming with solar, I would be placed on a TOU plan, where I will have a higher rate (peak rate) in the evening and thus I will be paying more when I draw from the grid and getting relatively lesser credit when I send back to grid during the day. Is my understanding correct? If so, is powerwall still worth it, given its current cost of ~11.5k.

Thanks in advance for any insight.
 
Here's a simple questionnaire to determine if you should get Powerwalls.

On a scale of 0 to 10, do you hate PG&E? (10 = lots of hate)

On a scale of 0 to 10, do you get upset seeing the Power Down 4 to 9 billboards on US-101 advising you not to cook dinner or run the air conditioner after you get home from work? (10 = you want to cook dinner and no dumb azz billboard is going to change that)

On a scale of 0 to 10, do you have family members in your house that would make you suffer if your AC's went offline when it was 100F outside? (10 = lots of potential whining and stress for you)

If your total score is >= 10, then get some Powerwalls. The cash ROI means nothing to my questionnaire. If you answered with combined score of 10 or more, you have intangible benefits of gaining as much independence from a mismanaged grid as you reasonably can. 100% grid defection is not realistic for most at this time.
 
Hi All,

I am looking to install a 6.4kW system in Bay Area, CA, USA. I currently have electricity service from pg&e. While I am trying to read as many as articles as I can get my eyes on to understand if I need a powerwall for my setup, I am unable to conclude either way. In my 15+ years in bay area, I only had a couple of short outages, so with that historical data (ofcourse it doesn't predict the future), I don't see a need for power backup. However, I am not perfectly clear how net metering works with pg&e. I am assuming with solar, I would be placed on a TOU plan, where I will have a higher rate (peak rate) in the evening and thus I will be paying more when I draw from the grid and getting relatively lesser credit when I send back to grid during the day. Is my understanding correct? If so, is powerwall still worth it, given its current cost of ~11.5k.

Thanks in advance for any insight.

"Necessary?"

No (but then again, solar isnt "necessary" either. How mad will you be, if there is a power outage (including a power safety shutoff), at your home at any point in the future after you get solar, knowing that even though you have solar, your home still has no power?

If you are trying to quantify it like "its this long till It pays for itself" then you probably dont need a powerwall. If you are only interested in perhaps running "a few lights and my fridge" if there was a power outage, a generator would be a much cheaper alternative.

If none of what @holeydonut posted above applies to you, then you likely should pass. Having had powerwalls since 2020 now, I wouldnt have solar again without them, I dont think, but its not because it completely pencils out in X years.
 
yeah; since being put on EV2-A (NEM1) my true-ups went from +/- $200 per year to about +$600 per year. without the powerwall, i calculate that it would be something like $1600 per year. so the PW gets me (for now) $1k per year and so that's something like a 22 year payback. and of course the batteries will degrade, and PGE will probably con the CPUC into pulling the rug out from under me again, so in fact i think we can safely say that my PW will never pay for itself.

still, like @holeydonut i think i'd rather light $1000 on fire every year rather than give it to PGE, so i'm a happy camper.
 
Here's a simple questionnaire to determine if you should get Powerwalls.

On a scale of 0 to 10, do you hate PG&E? (10 = lots of hate)

On a scale of 0 to 10, do you get upset seeing the Power Down 4 to 9 billboards on US-101 advising you not to cook dinner or run the air conditioner after you get home from work? (10 = you want to cook dinner and no dumb azz billboard is going to change that)

On a scale of 0 to 10, do you have family members in your house that would make you suffer if your AC's went offline when it was 100F outside? (10 = lots of potential whining and stress for you)

If your total score is >= 10, then get some Powerwalls. The cash ROI means nothing to my questionnaire. If you answered with combined score of 10 or more, you have intangible benefits of gaining as much independence from a mismanaged grid as you reasonably can. 100% grid defection is not realistic for most at this time.

I think this can't be stated enough as funny/silly the above sounds. I went in and have stated here many times that there is probably little/no ROI on batteries, but I think the flexibility/control/power/freedom of power outages/possible off grid future can't be understated neither. With batteries, you just don't worry (as much) if the IOU decides to raise peak time rates even higher since they know very well that a very small % of people have batteries due to their cost.

For me, I see it as $$ I just didn't waste on something else. There are enough Model S/X/$100k trucks/cars out there that if you decided to get that $80k car instead, there are your powerwalls/batteries. I don't think 1 battery is really enough for most folks to last overnight though (I have 2x Enphase 10s), but even with the AC on at a non-crazy low temp right now, I can get past the peak hours (4-9pm) and go back to using lower cost power after that. I'm a net exporter anyways so have so much saved up that I can probably run the AC at peak and still not worry.

Still, I've not had a single power outage yet since San Diego has pretty reliable power (so I can't convince myself I got it for that), but we do have the most expensive energy prices so depending on your use case, there is some ToU shifting one can calculate ($0.69/kWh On-Peak vs. $0.336/kWh Super Off-Peak for > 130% Baseline). If we were to go offgrid (for electricity only), I'm pretty sure we can easily do that with 1 or 2 more batteries and hook up the generator option. We rarely get long bouts with no sun in So Cal.

I did the calc earlier and when it wasn't WFH pre-covid, we would use 3x the energy from like 4-9pm vs. 8am-4pm which made batteries financially better. WFH made time shifting (and not having to charge the EV) less of a need really.
 
yeah; since being put on EV2-A (NEM1) my true-ups went from +/- $200 per year to about +$600 per year. without the powerwall, i calculate that it would be something like $1600 per year. so the PW gets me (for now) $1k per year and so that's something like a 22 year payback. and of course the batteries will degrade, and PGE will probably con the CPUC into pulling the rug out from under me again, so in fact i think we can safely say that my PW will never pay for itself.

still, like @holeydonut i think i'd rather light $1000 on fire every year rather than give it to PGE, so i'm a happy camper.
Are your calculations at today's rates? If so, I suspect your payback will be quite a bit sooner. PG&E rates are going up and up.

I have batteries so I minimize the money I have to send to PG&E, and also am insulated from their inability to keep the power flowing to my home.
 
I have a small house, with a small (4 kW) tesla solar install and 1 powerwall 2. We don't use a ton of electricity. It was a no brainer to go for powerwall
* climate change + wild fires == more PG&E outages
* live in Santa Cruz very close to the coast == storms
* single powerwall provides whole house backup for 20+ hours before including solar
* I run essentially off grid from February to November thanks to solar + pw at night
 
Are your calculations at today's rates? If so, I suspect your payback will be quite a bit sooner. PG&E rates are going up and up.

I have batteries so I minimize the money I have to send to PG&E, and also am insulated from their inability to keep the power flowing to my home.

the payback horizon calcs for my PV system (installed in 2015) are definitely out of date. it's true that the huge hit that EV2A represents to the PV payback has to be calculated against the rise in E1/EV/EV2A and i only did that calc in 2015. the horizon was something like 11 years at the time. i know it got worse but not sure by how much.

the PW vs no PW on EV2-A calc was done about a year ago.

i also have a running day-to-day comparison of PW vs no-PW as i have multiple PVOutput systems, two looking at just the solar and house and one looking at the meter only. for the last 30 days, there is a $100 delta between the battery/no battery systems (-$80 no PW vs +$20 w/PW).

on EVA a couple of years back my june/july numbers were like +$100 vs today at -$80. EV2 *really* hurts. i have had an EV as my primary car since 2011, so the usage should be similar.
 
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In sunny San Diego County we haven't needed a PowerWall yet. With the exception of a 3 hour power outage last year we have had very steady electricity provided by SDG&E since 2009 when we bought our home. We are not in one of SDG&E's Public Power Safety Shut-off zones so we haven't dealt with power being shut-off during high wind events.

Our solar 4kW system went in a little over three years ago. It produces more electricity than we use each year. We are a net exporter for at least 10 months of the year. For those few hot summer months where we use more than we produce our accrued NEM credits easily cover the monthly bill. At the end of three years our net SDG&E bills have accrued a $43.00 credit carried over to the start of year 4.

Hard to justify adding a PowerWall under these conditions.
 
With the new ability to charge from grid and export everything, it’s possible to arbitrage rates so the value proposition of the powerwall has significantly changed this year. Is it enough to pay for the powerwall? Maybe maybe not, but then again the Tesla app only gets interesting with powerwall so there’s value having that satisfaction of seeing it everyday. Plus PG&E will keep manipulating rates to make TOU rates less beneficial for solar customers and powerwall hedges against that.

At the time I placed my order, my powerwall was $7,777 after tax credits. It’s worth it to me.
 
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Where I live, PG&E is ALWAYS having time-outs, turning off the power with no notice, no idea of when it will return, or why it went off. I got power walls simply so I could watch a TV show when I wanted or have the lights on when I went to take a shower or got ready for bed. Nothing critical, you understand, just that in this century we should expect to have RELIABLE power. Until the power walls, we didn't have that.

So, yeah, twenty thousand for peace of mind might be steep for some, but with housing costing several million for most of us in Napa Valley, that's not so bad.
 
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With the new ability to charge from grid and export everything, it’s possible to arbitrage rates so the value proposition of the powerwall has significantly changed this year. Is it enough to pay for the powerwall? Maybe maybe not, but then again the Tesla app only gets interesting with powerwall so there’s value having that satisfaction of seeing it everyday. Plus PG&E will keep manipulating rates to make TOU rates less beneficial for solar customers and powerwall hedges against that.

At the time I placed my order, my powerwall was $7,777 after tax credits. It’s worth it to me.

true, though in theory the federal ITC is incompatible with grid charging. and in the end you can’t export more power than pge estimates you can generate with your PV plant. not sure what the rules are when you only have storage.

for me the difference between having the powerwall satisfy the home demand between 3p-12a/solar only export and “export everything” is about $2.50-$3 per day, at least during these summer days.
 
Where I live, PG&E is ALWAYS having time-outs, turning off the power with no notice, no idea of when it will return, or why it went off. I got power walls simply so I could watch a TV show when I wanted or have the lights on when I went to take a shower or got ready for bed. Nothing critical, you understand, just that in this century we should expect to have RELIABLE power. Until the power walls, we didn't have that.

So, yeah, twenty thousand for peace of mind might be steep for some, but with housing costing several million for most of us in Napa Valley, that's not so bad.
Is it necessary? no. Does it pencil out, not likely in a reasonable timeframe. what value do you place on peace of mind and satisfaction of being able to combat PG&E rates and tactics.

Our power went out at 6PM last night, it is still out. Currently estimated to come back on at 10, we’ll see… however, during that whole time we have had no impact from the outage. For me that is well worth it. Actually I lied about no impact…I had to reset the clock on the microwave!
 
I am still waiting for a long power outage to help justify mine, but just see it as a cool toy. Assuming it actually lasts 10+ years it will eventually pay for itself. I wasn't planning on getting one originally, but with the federal rebate and .99 financing Tesla had at the time I decided to pull the trigger.
 
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It is not just earthquakes for us. Fire, old IOU equipment and wires routinely giving out, and of course the next big solar flare...

I think we had more than five fires within twenty miles of us this week. Car crash, poorly maintained IOU equipment, lightning, are amongst the suspected causes.

All the best,

BG
 
It is not just earthquakes for us. Fire, old IOU equipment and wires routinely giving out, and of course the next big solar flare...

I think we had more than five fires within twenty miles of us this week. Car crash, poorly maintained IOU equipment, lightning, are amongst the suspected causes.

All the best,

BG


Don’t worry, here’s the CPUC’s solution to reducing your TOU rates. Interestingly you could do the same thing if you are a normal rate payer who loses power. Just sit there and stare at the wall! It’s free!

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I started an order without a power wall in NNV where we don't have a lot of power outages and then out of the blue I got a letter from the power company advising me that they are going to start utilizing brownouts for certain events ie; wind, fire, etc. I have a feeling in the long run as a few have said, I am going to be glad I have it. Peace of mind is part of the ROI to me.