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Are powerwalls a necessity for SoCal residents?
- Thread starter Carbonfiber
- Start date
hurjio
Member
The system needs to be sized right, but yes, you can have it so that you over-generate during the day to build up credits through net metering and use up those credits at night. Oversizing your solar system is probably more cost-effective right now than getting a powerwall, from a strictly financial standpoint.
Uncle Paul
Well-Known Member
The reason that PG&E stated is why so many So Cal people are installing Quiet Cool type fans. You can let them run quietly all night and suck in all that cool air. You cool down your interior walls, floors, furniture etc. This acts as a kinda cool mass battery that keeps your then closed up house cool long into the hottest afternoons.
Works well as a cost effective adjunct to installing a much smaller Solar system with equally quicker pay back.
Small Solar system plus Quiet Cool is lots less expensive than a much larger capacity Solar array plus Power Walls.
Works well as a cost effective adjunct to installing a much smaller Solar system with equally quicker pay back.
Small Solar system plus Quiet Cool is lots less expensive than a much larger capacity Solar array plus Power Walls.
So I got size for the medium system 8.16 by the Tesla advisor. I sent him my SCE bill and he took the highest usage month which was 29kwh/day. I also told him I will be getting a Tesla very soon and he did some calculations on his end to ensure my system would be sufficient enough to cover the charging and power the house. At this point I’m just trying to figure out if paying the extra $10k would be worth the investment for powerwall?
bkp_duke
Well-Known Member
The "payback" for the powerwall to pay for itself is for most people in SoCal something like 9-12 years (they have a 10 year warranty, so keep that in mind).
Also, it's not an all or none thing, you can add the PWs later.
I was "experimenting" while waiting for PTO until August. So I avoided pushing back to the grid. I was doing things like charging cars to 95% and seeing how fast the Model X and 3LR could do 0-60 to create places to put those excess kWs. And when I ran out of places I had to resort to things like turning off the inverters
. I suspect we will very negative come May next year.
To be fair that's 950 average across all 12 months; so a couple hot summer months (triggering their phone calls) I hit 1,200 kWh. But having moved from the midwest I don't personally think 1,200 kWh is too bad for a multi-generational household that can't just open all the windows at night due to medical reasons. Anyway, I posted about it in this thread. Water heater: Gas to electric conversion illegal in California?
If you're with PG&E - keep mind PG&E uses a jerk playbook. They try to trick homeowners into thinking the individual is the problem. This deflects attention away from the real problem: PG&E. Don't fall for their crap.
Anyway since this thread is about SoCal and SCE is only slightly better than PG&E... my response is "yes you should consider Powerwalls".
Others pointed out to me recently, the utilities in the CPUC can seemingly do anything they want to at a whim regarding the Time of Use (TOU) rates that PV customers must use. So, maybe today the TOU isn't so bad for you and your Net Metering true ups are tiny. But tomorrow, the utilities could easily make your daytime generation next to worthless while making your dusk/evening usage cost a huuuuge amount. Powerwalls will let you get around this by becoming your own load balancing solution instead of being beholden to TOU.
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It won't work that way each month. You need to think on an annual basis. See my graphs above
I have not tried one of those, but by us most nights we can do the same thing by just opening up the windows around 8-9 and closing in the morning before it gets warm. Another thing is to set the A/C to lower temps from 1030 AM to 2 PM (off-peak). That will pre-cool the house and you may be able to ride out the peak period without running the A/C too much.
People in the house are sensitive to air quality. I have MERV 16 filters and UV scrubbing lights on my HVAC air handlers. And the air handlers run 24 hours a day. I'm afraid I can't do the whole house fan option.
Uncle Paul
Well-Known Member
Quiet Cool also blows all that superheated hot air out of my rafters.
In my house the breeze is non existent. If you get a good draft/breeze the fan in not needed
In my house the breeze is non existent. If you get a good draft/breeze the fan in not needed
Definitely not as low. We had to run the A/C a few weeks in July and August through the peak and into the late evenings. The Powerwalls covered this period of time. So $0.00 to PG&E on those evenings and nights instead of $0.42/kWh.
You should consider one of the air sensor from Purple Air. I had not heard of them before all of our fires in NorCal, but now have one on order. I want to know how good/bad the air is outside my house before I open the windows. They also have inside house units which might be more useful to you.
Right sized is the right answer. Be carefull with "over sizing". Not sure how the southern Ca utilities work, but with PG&E, you get 2 or 3 cents for every kWh you over produce on an annual basis. You will never get an ROI on the extra capacity.
Right sizing would be sizing the system so the net annual bill is close to zero. My installer showed me their month by month projections for my system and how it was sized to be annual zero. I've compared their projections to actual and they have been within 5% every month except for 2 winter months that we did not get the usual rainfall. In those 2 months we beat their projection by 20%
Same here. Had not heard of Purple Air until the fires, but I have not ordered one yet. We do have 2 Molekule filters though
You could go to PVwatts, plug in your address, and it will tell you what an 8.16 system on your roof would produce.
But let's just say its 12,000 kwh a year.
Let's further say you use, on average, 1,000 kwh a month.
OK, so then, you figure out what your utility is doing, because a system sized exactly for what the house will use depends on a 1 to 1 net metering to make the math simple. That means if when the system is producing more than you use (in the day) you get credit at the same rate as when you are buying power at night.
If the rate is not the same, lets say your utility will do a time of use rate schedule. That might be, who knows, half of your usage? So for 6000kwh per year it might still "cost" the differential, or say $300 bucks a year if the differential is 5 cents. Six hundred a year if its 10 cents.
Not a disaster, the panels still save money, and $300 bucks will not, per year, cover the cost of a powerwall, so there is a possible answer.
By the way, a Model 3 has a 75 kwh battery, so if you charge it 50 times a year that's 3,750kwh you have to account for.
Yes that’s what I meant. Thanks for clarifying that. Did you come close to breaking even at the end of the year?
Did everyone trust Tesla proposal on solar panels and the set up?
Yeah, I check their site every time before I go outside or open a window. I run/walk a few miles every morning and I have put off a couple of days when the numbers were over 150. That "little smoke" smell is hazardous when it represents a lot PM 2.5 sized particles in the air.
Depends on if the utility has a special rate overnight for EVs. The one thing that PG&E does do is give an EV rate of 13 cents per kWh 11pm to 7am. Charging the car at that rate is better than charging car from Solar.
We were over 150 almost every day until today. We went to Healdsburg last week and the air was better there than here
