I am a SCE customer to be specific and definitely will be investing in solar panels pretty soon. I’m on the fence about getting a powerwall with the solar panels. Where I live (Pasadena), we hardly get blackouts. So I’ve read people who do end up getting powerwalls, can stay off the grid during peak hours. I’m a a little bit confuse about this part because, shouldn’t the solar panels produce enough energy during the day to supply power to the house during peak hours?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Are powerwalls a necessity for SoCal residents?
- Thread starter Carbonfiber
- Start date
SoCal Dave
Member
I'm with SCE and I decided against Powerwalls.
Besides backup, Powerwalls can help with TOUs and non bypassable charges. For the TOUs, I oversized my system to compensate. For the NBCs, I calculated NBCs to be pretty minimal and the cost for the Powerwalls didn't justify them.
Down the road I may eventually add them as the utilities start playing more games with fees, but for me right now I couldn't make the financials work.
Besides backup, Powerwalls can help with TOUs and non bypassable charges. For the TOUs, I oversized my system to compensate. For the NBCs, I calculated NBCs to be pretty minimal and the cost for the Powerwalls didn't justify them.
Down the road I may eventually add them as the utilities start playing more games with fees, but for me right now I couldn't make the financials work.
hurjio
Member
I'm also in SCE and have the same dilemma. From a strictly financial perspective, powerwalls used for TOU arbitrage will not pay themselves back for many many years (unless peak rates change drastically... the larger the cost difference between peak and non-peak rates, the better for powerwalls). Also, like you know, we don't suffer any extended blackouts, so any outage coverage from powerwalls would simply be a luxury nice-to-have. I think battery tech is still advancing and will get cheaper in the future. The last point is just how much you value reducing your reliance on the grid (subjective).
However, having said that, the argument to get a powerwall if you're getting solar at the same time is 1. the $2500 discount Tesla offers when combining solar and powerwall and 2. the ability to claim the 26% fed credit for the battery install as well as solar. That's quite a bit of discount, and I don't think battery prices will be dropping that fast to make up for the current savings. That's why I'm leaning towards getting 1 powerwall.
However, having said that, the argument to get a powerwall if you're getting solar at the same time is 1. the $2500 discount Tesla offers when combining solar and powerwall and 2. the ability to claim the 26% fed credit for the battery install as well as solar. That's quite a bit of discount, and I don't think battery prices will be dropping that fast to make up for the current savings. That's why I'm leaning towards getting 1 powerwall.
The non-blackout "math" I think is something like this (if there is a blackout the benefit of powerwalls is that you still have power.).
If the panel system is "undersized" you may be using all the energy it produces, so what happens is panels save money by allowing you to get, if you assume a 20 year system, power for about 10 cents per kwh, approximately. That's better than the 20 cents average now, let alone if you are in an area with higher rates (or if rates rise.)
Powerwalls are now the only way that you can "get" all of the power a system sized to produce the power you use day and night, all year round, if you get enough powerwalls. "Enough" being defined as enough to make it through the night.
Whether its "worth it" depends on projecting the cost down the line the utilities will charge from non-peak vs. peak. Becuase the pure economic benefit to powerwalls is that you don't have to sell at off peak and buy at peak. If that differential is 10 cents a kwh or more (and right now for me with LADWP its not quite) the powerwalls "pay for themselves."
If the panel system is "undersized" you may be using all the energy it produces, so what happens is panels save money by allowing you to get, if you assume a 20 year system, power for about 10 cents per kwh, approximately. That's better than the 20 cents average now, let alone if you are in an area with higher rates (or if rates rise.)
Powerwalls are now the only way that you can "get" all of the power a system sized to produce the power you use day and night, all year round, if you get enough powerwalls. "Enough" being defined as enough to make it through the night.
Whether its "worth it" depends on projecting the cost down the line the utilities will charge from non-peak vs. peak. Becuase the pure economic benefit to powerwalls is that you don't have to sell at off peak and buy at peak. If that differential is 10 cents a kwh or more (and right now for me with LADWP its not quite) the powerwalls "pay for themselves."
my design also has partial backup without backing the AC and 240v Tesla charger. This means in an outage I won't be able to use AC or charger which is fine with me. I have a supercharger close by in Santa Clarita. Plus we use AC only a few days in summer so not worth backing that up. When the grid is up, my AC and charge if needed would be powered by the Powerwall.
Its all math. If the system is undersized it may mean that that the system would not (at any time of the day) produce enough power to both carry the home loads and charge the powerwalls. If that does not happen, you would have to use Storm Watch to power the powerwalls from the grid or force their charging somehow.
A system may well be sized to where there is excess energy, just enough to charge the powerwall or walls, but not enough to conceivably run off the grid for days at a time. But its all math. You have to figure out average usage at time of day, then projected power generation at time of day, and go from there.
The real problem with solar power is it generates a lot of power when most people do not need that much in their homes, between 11 AM and 3 PM. The Powerwall lets you take this chunk of power and use it when you do want it, and for free. For most homes that is the afternoons and early evening. When temps are up and you run the A/C, cook dinner, etc. And this surge in demand is why Time of Use Plans are most expensive at these times.
The powerwall lets you avoid buying power at the high rates by using the power you mostly generated in the morning and early afternoon. And depending on battery size you may not even need to buy power in the morning or even the entire next day, which can be a lifesaver in outages.
And the impact can be dramatic. As an example here is my PG&E bill for months before and after adding solar and Powerwalls. I bet you can guess when we started using the Powerwall and SolarRoof.
The powerwall lets you avoid buying power at the high rates by using the power you mostly generated in the morning and early afternoon. And depending on battery size you may not even need to buy power in the morning or even the entire next day, which can be a lifesaver in outages.
And the impact can be dramatic. As an example here is my PG&E bill for months before and after adding solar and Powerwalls. I bet you can guess when we started using the Powerwall and SolarRoof.
I hate how PG&E shows the average temperature during a period instead of the peak/high temperature during that period.
They called me one time last year and told me "the average temperature was only 70 degrees" so I shouldn't need to use my air conditioner and I was a huge energy waster. I asked them "average was 70? it was like 90+ degrees average high that month!"
And they responded "well, the average temperature of both low and high. Since it's cool at night you can open all the windows let your house get really cold. And then once it's 90 degrees outside just keep your windows closed and it won't be so bad. The average will be comfortable and you won't be such a huge energy user."
I just hung up on that PG&E person. If that's their logic then they can just cram it. I hate how those jerks gaslight homeowners into thinking the homeowner is the problem. I hate PG&E.
SoCal Dave
Member
PG&E actually called you to complain about your energy usage? Reason #45,753 I'm glad I'm not a PG&E customer.
SoCal Dave
Member
You changed both to solar and Powerwalls at the same time right? What would your bill have looked like if you only did solar?
bkp_duke
Well-Known Member
I so would have had an expletive-laden tirade to give that person if they called me . . .
YES. my energy cost was over $0.40 per kWh on average and the bill said my tiered Plan hit the “!” Category for extraordinary usage.
PG&E sent me paper mailers, emails, and called me to advise me how I could do better. They told me I was in the worst 1% of energy use.
I posted in a different thread but I put all new appliances, all LED stuff, and have brand new HVAC. My monthly usage was about 950kWh and I don’t have an EV or pool.
bkp_duke
Well-Known Member
Correct, but you need to think of it in terms of $$$, and not kwh, simply because the utilities don't pay you as much for your solar during the day as what they charge you for your usage at night.
