Streamliner

I was curious if anyone here has a Tesla Powerwall setup and if so, if you are using it to charge your EV. We are planning a major home renovation and will install solar panels. I’m trying to learn about the most economical ways to charge an EV.

wildta

Have you read about NEM 3.0?
http://solarnegotiators.com/blog/nem...-need-to-know/

https://www.energysage.com/blog/net-metering-3-0/

Under CA NEM 3.0, the payback period for solar systems with batteries may be quicker compared to systems without batteries. The NEM 3.0 policy has shifted from net metering to net billing, which significantly reduces the compensation rates for excess solar power sent to the grid. This change makes the inclusion of batteries more economically favorable, as they can store excess energy for use during peak demand times or when the sun isn’t shining, rather than sending it back to the grid at a lower credit rate. While a battery is not required under NEM 3.0, it can provide more bill savings and potentially pay for itself if operated correctly. Adding a small battery can increase the bill offset to as much as 70%-90%, compared to a 55% bill offset for a system without a battery under NEM 3.0. So adding energy storage batteries with your solar panel system could lead to a quicker payback under the new NEM 3.0 billing model in CA.

Streamliner

I’ve got a LOT to learn. Thank you!

guess2098

from your location, you probably has same SCE as I do.
with nem1 or 2, you won't get too much back. the most I got is just 120 a year. most the time just $10~20 per year

here is my experience, just give you an idea, my SCE bill average is ~180. summer bill is about ~300-400 back to 2015
my 1st solar installed at 2016 and monthly payment 120 (after 30% tax credit), since then I only pay SCE monthly fee ~10 (now is 20)

don't think about charing your EV and power wall. on 2021, 2022, 2023 summer, all my friends without solar are paying ~700-800 a month during summer. I paid 120 solar +10 SCE fee only.
install solar will save you money in the long run. unless you don't use AC in summer.

now back to EV
last year I max out my roof with another 4.8kw panels, with 2 power wall (total 31400 before tax credit ~9.4k),
new loan is 388 before tax credit.
two EQS580 one using 17% a day another 10% a day, total 27% charged daily, current SCE monthly bill is 0 (20 fee).

with solar and EV
so now 0 gas fee, 20 SCE monthly, 120 1st solar loan, and 388 2nd solar loan = $528
vs.
without solar and no EV
average 180 sce bill, ~600 gas per mo = $880

ps. here is my solar cost 25700 (2016) + 31400 (2023)= 57100 - (8600+9430) tax credit = 39070

your question, when is the best time to charge with solar and power wall.
I will say the best time to charge is 8am-4pm. that way you dont need to import any electric from SCE because they charge delivery fee.
for me, M-F my wife leave the house ~ 6:20am, and I leave at 7:45am. her car will charge start at 4:30am, most the power wall will go to her car, my car charge after she left.
daily import about 7-13 kw depending AC running at night or not.
power wall will charge from solar and get full before 1pm on sunny day and start export extra power(15-25kw daily). my Tesla app setting is self power, and limited 15% of power wall reserve.

nath_h

Yah, we've got two, and solar. I don't think this is an economical consideration for you...it is likely to be a bad financial decision. But, you will have peace of mind that you will always have power if the grid is interrupted for whatever reason. One doesn't have to be a doomsday prepper to be concerned that our country's rickety grid could potentially be out of service either from damage or cyber attack for a substantial amount of time.

c4004matic

A powerwall module has 22kw. An EQS has a 120 kw battery.... Is it me, or does the math not add up? Furthermore, it can only provide a max of 6.6 kw continous. So, not only would it be impossible to charge the vehicle more than 20% a night, it would be pretty slow at that! Lastly it would leave no juice for anything else.

nath_h

Yah, battery charging was not even a consideration when getting our Power Walls...just an emergency plan so as not to be completely helpless in an emergency situation, and be the envy of our neighborhood when our AC is on blast in July when the rest of the neighborhood is dark

guess2098

you dont use power wall for charing your EV! you use power wall to avoid peak time rate.
powerwall+ provide max 9.6kw continuous, almost all the new order is using powerwall+, the new powerwall 3 provides 11.5kw
also you can still use over powerwall can provide, say I charge my car at 9.8kw, gateway will split to two input, 9.6kw will from power wall and 0.2 from grid.

c4004matic

So you spend 10k to save 10 bucks when you charge. Boy, thats going to a loooooong time to recoup!. You can also simply use the charging program to only charge in off peak times.....

guess2098

as I stated, powerwall is not for charging EV.
anyways, it takes about another 2 years 11 mo to recoup.

Streamliner

I appreciate all the comments, much of it blowing right over my head. As I said, I have a lot to learn on this subject. I believe we will put in at least one Powerwall, if for nothing more than as a backup when the grid goes down.

Highline-Autos.com

Hey, same! Well my mom does. Here in AZ she is fully self sufficient in a 2,700 Sqft. house when it comes to power. Solar runs the home and fills the Tesla batteries during the day, then the home uses the batteries at night. Our energy scare here in the desert is the grid being over run due to A/C on the extremely hot days... which will kill the power to neighborhoods, blocks, sometimes even towns for a couple hours.

Trenton O. Gibson
tgibson@highline-autos.com
Highline Autos
Direct: 602.909.9216
Office: 480.348.0777

23-EQS580-SUV

I'm thinking about added 2 Tesla Powerwall to my current solar system but i don't see the benefits.

I'm on CA NEM 2.0. My 5-kwh systems cost $21,000. To add 2 Tesla Powerwall 3 Batteries will cost another $21,000 (including installation), that $42,000 total.

Before my PTO during the summer/winter my electric bill cost ~$300-$400 per month depend on if I charged at home every week or not. After my PTO, during October to March my solar make ~12-20-kwh per day that with the HVAC running and charging at home, my electric bill average ~$30-45 per month.
During April to September on a clear sunny day my solar make 31-kwh Max per day. With the AC set at 70 degrees, charging the EV every week and kids are on summer breaks and relative visiting. The electrical company (SCE) owned me money (credits). So, I don't pay anything to charge my EV at home. I still have a negative balance since April.

I pay $21,000 cash for my solar system. Assuming my electric bill average is ~$350/ month i would get my money back in 5 years ($21,000/$350/12 months=5 years).
Solar $21,000 plus $21,000 Batteries. $42,000, i would pay off the system in 10 years?? By the time i pay off the system the batteries would be out of warranty.

Adding Battery ($21,000) would not benefit me in the long run.
If you buy solar now, you'll be on NEM 3.0 and you going to get screwed by the electric companies.

guess2098

I am not sure adding powerwall will change nem2 to 3. check with SCE 1st? also powerwall has 30% tax credit, so it is not 21000, after tax return is 14700, but check with your CPA (I think tesla also give discount, you can check with Tesla too)

but you said you are charging your EV and still have credit in SCE after 12 billing cycle, I would suggest not to buy powerwall.


from Tesla website
I have solar installed and have received permission to operate (PTO) from my utility under NEM 1.0 or NEM 2.0. Can I add a Powerwall to my system and maintain my existing status?

• Yes. The current policy would allow customers on NEM 1.0 and NEM 2.0 to add battery storage later. For existing NEM 1.0 and NEM 2.0 customers, adding battery storage does not affect your existing status. It is important to understand, however, that policies may change so this should not be taken as a guarantee of future policy.

wildta

Adding batteries to a grandfathered NEM 2.0 system does not change your NEM status. You can also add, I believe up to 10%, additional panels to a grandfathered system without forcing a change to NEM 3.0.

MB37

I guess I'm still old school with my NG generator when it comes to backup power. We have the largest NG reserve in the world. While it is not cheap to use as backup electricity, it is just that . . . for backup. The infrastructure works in Texas cities. I've thought about battery power as backup, but I think it's only good enough to keep your food from spoilage in blackouts and maybe keep the LED lights on. Here in Texas, we need our HVAC most of the time in a year.

I'll wait until the battery power backup is more mature.

nath_h

Yah, backup battery is of limited use, unless you have solar to refill it everyday. If your goal is only to have power during a brief 3 hour outage, a PW would be fine. For alleviating concern about an extended outage, you need solar to have it make sense.

hlothery

Agree. My 22kW Generac NG generator is the way I decided to go.

matt12eagles2

Old thread I know,

but we have both powerwalls + a Tesla wall charger. Fair warning… the EQS is NOT a fan of listening to the Tesla’s “do not charge when” schedule lol so make sure to use the one in the Mercedes app.