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Advice on adding solar rental and Powerwall for Model 3

Advice on adding solar rental and Powerwall for Model 3

Has anyone looked at the new solar rental product with Powerwall (PW)? Any feedback or advice? I have a model 3 that I charge 20 kWh on an average night. My house uses 35 kWh in average per day.

I live in LA (Pasadena) and it gets really hot July - September, house electric bill around $200. I have a separate meter for EV charging, plan to keep the mode 3 on TOU-EV1.

I am considering renting 7.4 kW system maybe with 1 PW ( would love 2 but it’s pricey). 1 PW isn’t enough to be self sufficient on most days. I am done some calculations showing that I need 11 kW and 2 PW to be self sufficient most days, but this system is too pricey and may not even fit on my house.

Any advice people can share is appreciated. Anyone rent the panels yet with the new program? How does the install look? Smooth process? What happens if the system fails? I am afraid that my bill will skyrocket since I am in tiered pricing now but have to move to the terrible TOU plan with SCE that charges $0.45 from 4-8pm.

Thanks for any help. And yes I will cross post in the Energy forum (all my friends are here in 3).

slingshot18 | 12 september 2019

TOU-EV1 usually isn’t great with solar. How many more months on the 24 month commitment?

andy.connor.e | 12 september 2019

You have indicated you use on average 55kWh per day. You also indicated that in a really hot month your electric bill was $200 which is probably higher than average due to the excessive AC usage maybe??

Either way, If the rental is going to be $200 per month its not worth it financially. I dont think it would make sense to rent equipment unless it was under $150 per month.

Right now, the solar roof estimate for me is around $210 per month without powerwall. I have to get a new roof next year and i've had someone come bay and give me a quote for a 10 year loan at $200/mo. So if a new roof is going to cost the same as a solar roof, i'd rather get the solar roof.

Tip: If you own it, you eventually stop paying for it. Rent is forever with no assets in the end.

jimglas | 12 september 2019

I purchased an 11kW array for my house and get 100% offset. Its set up for battery back-up, but too expensive for me and little benefit since utility in CO pays me for excess that I produce during the day. When battery prices come down I will get PW or other battery to allow me to go off grid

bjrosen | 12 september 2019

Do the math to determine if it makes any financial sense for you. I looked at it and it made no sense. The 11.4KW system rents for $150/month. They claim that it produces 26KWh/day, * 30 days that's 780 KWh. That's 19.23 cents/KWh. I pay 21.4 cents/KWh so under the most optimistic scenario I might save 2 cents/KWh. You live in LA so you don't have to worry about snow on the panels reducing the output, I do. My electricity needs vary a lot between summer and winter, in summer I use 2400KWh/month, in winter 1600KWh/month, the difference is air conditioning. If I sized a system for my summer needs I'd be paying $450/month, that's a little less than my summer bill but a lot more than my winter bill. If your bills are steadier than mine then maybe you could break even assuming that you have an electric rate that's as high as mine but I suspect that you pay less in which case it won't pay at all.

lbowroom | 12 september 2019

bjrosen - that estimate doesn't make sense. I have a 6kW system that isn't optimized south facing and average 25kWh/day

andy.connor.e | 12 september 2019

You will pay more in rent than the value of the energy it produces per month. You are better off buying your own array for your roof so that one day you will own it and can reap the actual benefits of having solar. Solar is not an incentive if its a rent payment for the rest of your life. Its no different from a utility bill.

bjrosen | 12 september 2019

lbowroom: The estimate is from Tesla's size guide

https://www.tesla.com/energy/design?attribution_eid=695409

Where do you live?

lbowroom | 12 september 2019

BJR

Southern California, you?

lbowroom | 12 september 2019

Andy, the cost per kW is fixed. If it's less than what you pay your utility than it is a savings. One that increases as your utility raises rates. For people who can't afford the cash outlay to buy, it's still better than paying the utility. The savings are smaller but instant, not delivered over 6-10 years with an up front purchase

andy.connor.e | 12 september 2019

Ya, depends how long you plan on staying in your property for.

lbowroom | 12 september 2019

BJR,

Don't know what website you're reading. Even in Alaska the 11.4 system puts out 28-35kWh per day. Your pricing is off though. the 11.4 is the large system for $199/mo

lbowroom | 12 september 2019

In CA

Small

3.8 kW1,000 - 2,000 sq ft home
•Produces an average of 14-19 kWh per day
•Best suited for a home with an average electric bill of $90-$110 /mo

Medium

7.6 kW2,000 - 3,000 sq ft home
•Produces an average of 29-39 kWh per day
•Best suited for a home with an average electric bill of $170-$230 /mo

Large

11.4 kW3,000+ sq ft home
•Produces an average of 43-58 kWh per day
•Best suited for a home with an average electric bill of $260-$340 /mo

lbowroom | 12 september 2019

Prices
Small $65
Medium $130
Large $195

kevin_rf | 12 september 2019

I realize SoCal is different, but if I had my solar system to do again, I would mount it on a track to get that 30-40% boost a tracker imparts.

This also assumes you have the land, which is always an issue in SoCal.

cybergrafx | 12 september 2019

I was looking into a PowerWall until I ran into a guy who does the Tesla PW instals at a local San Diego brew pub. I have solar on my house and he said that I would need two PW installed for my 3,000sq ft house.
He also said "off the record" that he would not recommend getting one yet, He said the technology is still improving so fast, they dont last that long and the ROI is little to none.

I would love to be off the grid but I'm holding off...

andy.connor.e | 12 september 2019

@cyber

I completely agree. PW can be installed at any time and the solar array does not require it.

beaver | 12 september 2019

@slingshot18 I have 10 months left on TOU- EV1, I pay only $0.085 total per kWh including taxes and fees for charging after 9pm, I think it’s a good deal. I would like to just put my house on solar and use the grid as a cheap battery overnight.

I have done some math, I think it’s right:
Ignoring my Model 3 charging on dedicated meter...
1,500 sq ft home
35 kWh per day average for full year (between 15-60 kWh per day)
Last years SCE bill $1,800 for my house
Projected cost for one year rental for 7.5 kW system is $1,560 ($130 x 12)
+ usage charge from SCE since I won’t have Powerwall is $500 (I looked at three examples and calculated my new TOU grid feed or pull by hour and extrapolated for the year)
New cost $2,060
So it will cost me $500 more per month and I have the risk that the system fails then I get destroyed for peak usage without solar.

Seems like even with the zero installation and zero removal fee I will still lose money. This is disappointing. I may still do it for environmental reasons but not financial.

beaver | 12 september 2019

Quick number update
Last year grid tiered SCE plan $1,800
Projection with 7.5 kW Tesla solar panel rental and balance pulled from grid $2,200 ($1,560+$627)
So $400 more expensive to add solar :(

Look correct?

bjrosen | 12 september 2019

@lbowroom. I live in MA. The Tesla website has the following figures,
Small
3.8 kW1,000 - 2,000 sq ft home

Produces an average of 9-13 kWh per day
Best suited for a home with an average electric bill of $60-$90 /mo

Medium
7.6 kW2,000 - 3,000 sq ft home

Produces an average of 17-26 kWh per day
Best suited for a home with an average electric bill of $110-$170 /mo

Large
11.4 kW3,000+ sq ft home

Produces an average of 26-39 kWh per day
Best suited for a home with an average electric bill of $170-$260 /mo

The large system is $150/month.

It looks like you get almost twice as much sun in CA as MA, that's the big difference in our numbers. We have snow and lots of huge trees so solar just doesn't work for us.

lbowroom | 12 september 2019

beaver, what is the $627 projected cost based on?

beaver | 12 september 2019

@lbowroom

I estimated the annual difference in grid supply vs usage for the panels. I split the SoCal year into 3 periods: summer (July - Oct), winter (Nov-Feb), and other (March-June). I found average days for these periods and downloaded my hourly usage and estimated hourly generation using data on solar hours per day for LA. This tells me my positive vs negative contributor to the grid, which I give a price according to the TOU plan. I add it up to determine the average daily credit or debit for SCE an extrapolate to the full year. I then add the fixed monthly charges ($25) and the total for the year of my expected payment to SCE is $625. I could reduce this in half with 2 Powerwalls, but then I am out $20k and destroyed my ROI.

Whewwww that was long winded. I have a spreadsheet of course :)

lbowroom | 12 september 2019

Sorry, I didn't wade through exactly how you estimated. I don't think you're calculating that right. With net metering you bank what you create and only true up once a year. You get credit at the higher peak rate when you exceed production during the day and pay low rate at night. You can get a quote through someone like Sunpower that will do a true analysis for you. You can then compare that to the Tesla plan.

beaver | 12 september 2019

@lbowroom

My understanding is that SCE tracks the cost for annual true up not pure kWh due to the different cost (value) of energy throughout the day due to TOU plan. I don’t think it’s just straight kWh. The problem I see is that solar doesn’t generate much during the most expensive time of day 4-8pm.

jrweiss98020 | 12 september 2019

beaver, if you have a Powerwall or 2, they will likely be able to adequately supplement your PV panels to 8pm, so you don't have to buy any electricity at that time.

I have 9KW of PV and 2 Powerwalls, completed Aug 21. Since then, there has only been 1 day in north Seattle where there was not enough sun to fully recharge the Powerwalls after overnight use (after discharge to ~66%, they only got to 91% the next day). Other than the 3W that the meter uses, I've only bought 1 KWh of electricity since the installation.

When calculating ROI, you might add in a factor that adjusts for the backup when the grid goes down. Without that, my payback period is about 35 years...

beaver | 12 september 2019

@jrweiss98020
Thanks I agree ideally I would just get 2 PWs and be net zero with my utility. I just don’t want to spend the $20k right now.

How was the survey, install, appearance of conduit, service? Did you rent or buy? Thanks!

nukequazar | 12 september 2019

One thing to consider about rent vs purchase... I tend to buy but in this case... Ten years from now panels may be so much better and less expensive that renting for now may be a good idea. Also, do we really know how long they will last baking in these? Rentals basically have a lifetime warranty.

nukequazar | 12 september 2019

Correction: "baking in the sun?

Marbix | 12 september 2019

Huntington Beach SoCal here. My cash-purchased 7.15 kW west-facing solar panels and 2 PWs were installed back in May. The panels generated 38.6 kWh today without a cloud in the sky. My PWs are typically down to 60-80% after powering my house overnight until the solar starts producing again.

I work from home and normally charge my Model 3 during daily peak solar at a rate of 24A to stay mostly within solar output. If I am impatient, I can charge at the full 48A and my PWs will handle what isn't covered by the solar. I'm still grid-tied but don't draw anything substantive. I'm ready for a zombie apocalypse class extended grid outage, LOL.

Note that each PW can only support 30A / 5 kW of load, so if you're in a hurry to charge your Model 3 and don't want to pull from the grid, you will need at least 2 PW to support that.

I'm on SCE legacy TOU-D-A, but that doesn't really matter since I'm self-powered.

beaver | 12 september 2019

@Marbix thanks for sharing, that’s the setup I want but with 11.5 kW since Pasadena gets a lot hotter than the South Bay. Out of curiosity how much was the full system? Was the install done well?

I am planning to add a second Tesla, mode Y or Xdor my wife, so we will need 4-5 PWs if we want to be self sufficient and not draw from SCE at night to charge the EVs.

I want to make a solid first step, perhaps the 7.5 kW system without PW for now. I talked to a rep and there appears to be no cost savings to adding the PW now vs later. I thought they waived the extra install and inverted but the rep said no.

shawncordell | 12 september 2019

Prior to getting a second Tesla, I was able to power my entire home, charge my Tesla and even send excess back to the grid. After adding the second Tesla, my solar credits are starting to deplete. But, I haven’t had a bill since installing the solar system 2 years ago. I have an 8.12 kw system with 2 powerwalls. I just put a deposit down for another 4.41 kw which will bring my system to 12.53kw.

My system faces east and I live in Texas and get pretty good sunshine. The new panels will face west though. I also have microinverters.

I paid cash for my panels and powerwalls. After rebates and incentives, the 8.12 kw system was around $9900. The 4.41 kw system will run me $6855 after the 30% off. I paid cash for the powerwalls also but I bought them from a Tesla approved 3rd party vendor and they were $16,000 after the 30% off.

beaver | 13 september 2019

@shawncordell
Add 2 more PWs and you will have my dream setup. 11.5 kW and 55 kWh of battery storage so I don’t have to pull from the grid at all on a sunny day. I will need to charge about 40 kWh a night across the two EVs.

nwfan | 13 september 2019

@shawncordell, I added to my solar system after purchasing 2nd Tesla Model 3.
I also have a battery. But my panels face all four directions. During winter months
my north facing panels produce about 0 kWh.

I bank excess power to draw on during winter months and the rainy days.
My power bank with my provider sitting at 2353 kWh.
17kw system with a 16kw battery.

My power bill was $2.49 for the month of Aug.
City Sales Tax and Miscellaneous Gross Receipts fee.

shawncordell | 13 september 2019

@beaver I may add one more powerwall. Right now I can charge both Teslas at different times and never draw anything from the grid. It’s pretty sweet!

@nwfan That’s a pretty sweet system you have there. After my expansion, I should be able to start building up my power bank again. My father-in-law is sitting on about 8,000 kWh worth.

Marbix | 13 september 2019

@beaver I paid $44K for my system back when they were custom designs before switching to the small/medium/large business model. There was some struggle iterating through design changes with Tesla and Tesla's interfacing with city permitting (it can be super-hard to get Tesla to return phone calls or emails), but the install was clean and I'm happy with the performance of the system.

Like you, I am planning to add a second Tesla EV in the future, and I will be having it load-share my current 100A EV charging circuit, so we're talking 80A of draw if both were to charge at the same time. That would have required 4 PWs to handle, which was more than I wanted to spend, so I've opted for now to NOT have my EV circuit in the backed up load center.

As long as the grid is up, my EV charging can draw from solar and my 2 PWs if needed, but if the grid goes down, so does my EV circuit. Routine outages of a few minutes to a few hours would not be unduly disruptive because I would just resume charging when grid power comes back. But for the case of an extended grid outage of days or weeks, I would EV charge from my 30A clothes dryer circuit which is backed up. That's a reasonable function vs. cost compromise for me given the hopefully low (but non-zero) likelihood of the extended disaster scenario.

beaver | 13 september 2019

@shawncordell that is a great setup and keeps the battery size you need reasonable.

@Marbix thanks for sharing, good idea on having a dryer plug backed up so you can charge some if the grid goes down.

I think I will start with the 7.5 kW rental and wait on the Powerwall, I wish their was a used program so I could get 2 for like $10k, that would be sweet

andy.connor.e | 13 september 2019

"Quick number update
Last year grid tiered SCE plan $1,800
Projection with 7.5 kW Tesla solar panel rental and balance pulled from grid $2,200 ($1,560+$627)
So $400 more expensive to add solar :(

Look correct?"

Yes $400 more expensive to add solar. But you did not factor in how much the solar panels are going to reduce your electric bill. If they cant save you $400 in electricity per year they're not worth getting.

andy.connor.e | 13 september 2019

Nevermind forget that i didnt read far enough down.

But in hindsight it would be more expensive to rent the solar because thats the only way it can make money. If the value of the energy the solar panels produced was higher than the rental cost then they wouldnt rent them. The customer would literally be making money off the solar panels they are renting and thats not a good business model. Again, why i kind of suggest buying them so that one day you're not paying solar rent, and you can actually have your investment clear your utility bill entirely and be paying for the panels still.

jrweiss98020 | 13 september 2019

I'm just north of Seattle, and bought my system from A&R Solar. I highly recommend them to anyone in this area.

beaver | 13 september 2019

Tesla claims online that “solar subscription” will be profitable for users.
https://www.tesla.com/support/energy/solar-panels/learn/rent-solar

It really depends on your utility, system size relative to your home, and your usage. I have been playing with the assumptions, if I get the full 7.5 kW in the summer as promised then I should be nearly break even on today no solar vs solar panel rental.

andy.connor.e | 13 september 2019

Im going to put a reservation down on the solar roof and see what happens. I need a new roof next year and i need them to start giving me some realistic numbers, since there have been a dozen articles in the last couple months about Tesla significantly reducing the price of the solar roof. Will let everyone know one way or another how it goes, because i expect it will be many months before i hear anything.

slingshot18 | 13 september 2019

@nukequazar Warranties keep climbing because they are designed and proven to last baking in the sun. My small system has a 25yr warranty and my new, larger system has a 30yr warranty.

beaver | 13 september 2019

Update:
I canceled my 7.6 kW solar panel rental because my roof doesn’t have enough space and I was downgraded to a 3.8 kW system. This isn’t big enough to cover my needs, my bill would have skyrocketed due to penalty for needing the grid during the day on the mandatory TOU plan.

The assessment layout put 8 panels on my south facing roof and 4 on north facing. The north facing ones would not generate much.

I am bummed, I was ready to go solar but I will have to wait.

shawncordell | 13 september 2019

Oh wow!! I’m sorry to hear that.

Passion2Fly | 14 september 2019

I don’t get it. If the 7.6kW makes sense financially, why wouldn’t the 3.8kW make sense as well? The rental price is cut down in half as well... so the price per kWh is the same for both systems... am I missing something? Forget the PW for now.

kevin_rf | 14 september 2019

He had a suboptimal roof... Depending on pitch, those 8 South panels would be a 2.4 kw system with the other 4 panels just being there for looks. Now if he had a West facing roof, it might work with a tou since max production would be during peak demand.

kevin_rf | 14 september 2019

If the goal is to outsmart the tou, might be worth skipping the panels and just get a couple of powerwalls. You can charge them off peak, and tap them during peak demand.

With all the solar in SoCA, the actual every demand minus solar follows a duck curve
https://images.app.goo.gl/vfheiRjAwFyAsBPg6

beaver | 14 september 2019

@Passion2Fly
I have a detailed model by hour and season of how much my house needs (downloaded the historical data from my SCE account) and I built a simple solar generation model based on public data for LA. I calculate my hourly “revenue” and “cost” using the TOU plan details.
It shows that if I only have 3.8 kW I have to pay SCR $1,000 more per year than I do today. With 7.6 kW I would be close to the same including the Tesla rental cost. I have tiered pricing right now, $0.18 for first 600 kWh then $0.25. The TOU-Prime plan is $0.38 from 4-8pm when I have a large need for AC and living but the 3.8 kW can’t cover it and doesn’t bank enough before 4pm due to price difference. It only pays $0.13 per kWh for the rest of the day including peak solar from 10-4pm.

beaver | 14 september 2019

@kevin_rf yes the “duck curve” shows up in my data and is real, and this is the reason why SCE charges higher from 4-8pm, their own mega solar generation Is lower and the grid needs are still high. It all makes sense, but it’s disappointing because I want to go solar. At least in California a large amount of grid power is solar generated, so using the grid from 10-4pm is pretty clean already.

beaver | 14 september 2019

And there is an alligator curve for wind power! The good news is it stays high normally until the early evening, so it can help balance solar out.

https://www.greentechmedia.com/articles/read/renewables-integration-in-t...

beaver | 14 september 2019

@kevin_rf interesting idea on the Powerwalls without solar. The problem is the payback time is long. I use at most 13 kWh at peak (4-8pm). So one powerwall should be enough to not pull from grid during peak hours. This will save me only about $325 per year since my average cost is only $0.16 per kWh hour today, and TOU is $0.13 off peak. So at a total cost of $11k for 1 installed PW it will take 33 years to pay back. :(

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