How would home solar panels with powerwall batteries works with charging the Rivian?

[TeamDavid]

Hey everyone,

I had a question on how home solar panels with powerwall batteries works with charging the R1S. I'm trying to see if we have to change up our charging routine once we get the solar panels installed. Here are some of my details.

I'm in california in the SF Bay area. We are getting Tesla Solar (9.72 kW system) with 2 power walls (27 kWh total). We are currently using the Rivian wall charger hard wired in with 60 amp breaker. Daily charging habits - at the end of the day, the battery hovers around 50% and charge to 70% every night at midnight. We currently have the PG&E EV rates so from midnight to 3pm it's $0.27 a kwH.

My question is once the solar system is installed, would we be better off waiting til the sun comes up to charge? Can my solar capacity provide enough to directly charge off of? If not, would we just get solar credit in the day, and use up that credit charging at midnight?

We are new to EV's and don't even have solar installed yet, but just trying to figure out how this will all work. Thanks!

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[solaskaze]

That's barely enough to fill up your R1 (total kWh or max charge rate -- the latter easily under max rating) with little to spare for the house: what's your use rate? Regardless, PG&E has a calculator that will tell you exactly what the cheapest setup it, and, if carbon neutral is your goal, you can opt for slightly more expensive night charges that should be (not verified) carbon neutral. So: 1) go check out the calculator under your account 2) don't worry about using 60amps -- your daily usage allows you a very casual (slower) charge rate overnight.

 

[Whataboykie!]

Well good luck. I have a 9kW solar system in my house in PA with a single Tesla Powerwall. I also have a Tesla wall charger and have had very good results. I have Tesla Model Y.
I was told by my local power co, that we don't have different rates for different times of the day, only businesses have different rates. This means I can essentially charge whenever.
I have also subscribed to SREC, and sell any excess back to the grid.
I have been receiving small checks every month, ranging from $20 to about $45.
I moved to Florida and bought a Rivian. I had a spare Tesla wall charger and bought the J1772 connector and can charge my Rivian without any issues so far. Over a year now.
The house is new and I had a 10kW solar system installed (31 panels) and two Generec batteries each with about 10kW. The system costs $73,000! And I received a credit from the IRS of about $21,000!
My provider charges me .13c/kW hr. I charge mostly when the sun is shining, producing a constant 9+ kW an hour, and works like a charm. I sell quite a bit back to the grid, but only get about a .05c/kW credit.
I find that when I charge my Rivian, I consume about 12kW per hour, and my system uses the batteries mostly until they are depleted, then switches to the grid.
With AC and my pool pump running, my house consumes about 3-4kW an hour, so I charge mostly after 6pm when the AC and pool pump is off.
When I have to charge my Rivian during the day, my house consumes 14-15kW/hr.
I don't know if this answers your question, but all I can say is, like gasoline, your cost of power will never go down! So, you're doing the right thing.
My house is a single story and about 2800sf.

 

[TeamDavid]

Awesome, good to hear other peoples experience. It gives me some insight of what I have coming in the near future.

 

[NY_Rob]

Keep in mind you're also going to see a gigantic variance in total kWh/day output based on date/daylight hours per day and the very low height of the winter sun in the sky...

Look at my daily output for May 12 (99.71kWh) vs Christmas Day (28.04kWh) and by the graphs you can see both were cloudless days... just less light on Dec 25 than May 12th.

 

[evguy]

I suspect you'll still need to do most charging overnight. But if you can leave it plugged in in the afternoon, I think you can configure the Tesla system so that any excess kW coming from the panels goes to the Powerwall, the vehicle or both.

 

[Mark_AZR1T]

To the point. You will not be able to charge your R1 on solar more than a few kW a day on your sized system, if you want to maintain battery for the entire night. You need triple the solar capacity to make it work.

I have 17kW of Tesla panels and three (3) Powerwalls and live in AZ (tons of solid solar producing hours). We downsized from a very large house to a 2000 sq. ft home and have about maxed out our capacity. My goal was to create a gas-station at home for our electrical vehicles.

We have two R1's (T and S) and I can add about 20% to each a day in the Summer and 33%+ per day outside of summer. Summer we have a higher load because of AC use. We went all mini-splits and our central AC is a back-up. Outside of summer we absolutely have a fuel station at home. Summer we can add power to our batteries, but this is not always sufficient. We pay $0.065 per kwH from 11pm to 5am, so that is affordable.

I just want a fuel station at home, it's my personal thing . You need to at least double your capacity if you want a true fuel station is my opinion. Sorry for the convuluted message....but I'm sure you get the picture.

 

[superfly_snook]

I believe with NEM 3.0 you’ll be best off charging your powerwall batteries during the day while generating energy and then using the batteries in the peak rate times of 4pm-9pm to power your house (that is SDG&E peak, PG&E may be different). If powerwall is slick enough to divert excess after charging fully to cars you have plugged in then for sure take advantage of that b/c any energy you send back to the grid during the day is generally going to cost you more if you take it back out later. All that aside I would guess charging after midnight is still going to be best from an economic perspective, with the one caveat that excess (your powerwalls are fully charged) generation during the day would be “free” to use to charge any cars while it’s being generated and assuming Powerwall can divert it rather than send back to the grid.

 

[mikehmb]

Hey everyone,

I had a question on how home solar panels with powerwall batteries works with charging the R1S. I'm trying to see if we have to change up our charging routine once we get the solar panels installed. Here are some of my details.

I'm in california in the SF Bay area. We are getting Tesla Solar (9.72 kW system) with 2 power walls (27 kWh total). We are currently using the Rivian wall charger hard wired in with 60 amp breaker. Daily charging habits - at the end of the day, the battery hovers around 50% and charge to 70% every night at midnight. We currently have the PG&E EV rates so from midnight to 3pm it's $0.27 a kwH.

My question is once the solar system is installed, would we be better off waiting til the sun comes up to charge? Can my solar capacity provide enough to directly charge off of? If not, would we just get solar credit in the day, and use up that credit charging at midnight?

We are new to EV's and don't even have solar installed yet, but just trying to figure out how this will all work. Thanks!

Looks like you’re on the EVb rate plan for the $0.27/kWh 12a-3p (same as mine). Also, if you’re doing solar, you’ll be on net-metering. Which just means kWh-out (net) over the year is what your bill will be in December.

You’ll need to get a baseline of your other usage to map out a way to optimally use your solar and take minimal from the grid. It’s doable with the size system you have, especially if you’re only using ~25kWh/day (per your 50-70% comment).

Of course, this will need to be adjusted based on when you need to actually drive the truck. Again, doable, and kind of a fun puzzle to solve IMO.

 

[SANZC02]

Hey everyone,

I had a question on how home solar panels with powerwall batteries works with charging the R1S. I'm trying to see if we have to change up our charging routine once we get the solar panels installed. Here are some of my details.

I'm in california in the SF Bay area. We are getting Tesla Solar (9.72 kW system) with 2 power walls (27 kWh total). We are currently using the Rivian wall charger hard wired in with 60 amp breaker. Daily charging habits - at the end of the day, the battery hovers around 50% and charge to 70% every night at midnight. We currently have the PG&E EV rates so from midnight to 3pm it's $0.27 a kwH.

My question is once the solar system is installed, would we be better off waiting til the sun comes up to charge? Can my solar capacity provide enough to directly charge off of? If not, would we just get solar credit in the day, and use up that credit charging at midnight?

We are new to EV's and don't even have solar installed yet, but just trying to figure out how this will all work. Thanks!

Are you grandfathered into NEM2?

I have a 6.2 kW system with a single Powerwall on NEM2. I usually charge over night from the grid. I power my house from 4 to 9 PM from the Powerwall so not paying the crazy 60-66 cent peak rates. Let the solar recharge during the day sending excess to the grid, then use grid credits to charge overnight.

I had credit on my account from the last 12 month settlement period. Just did the 12 month settlement again in August, paid a total of 12.93 to SCE over the past 12 months.

 

[Whataboykie!]

To the point. You will not be able to charge your R1 on solar more than a few kW a day on your sized system, if you want to maintain battery for the entire night. You need triple the solar capacity to make it work.

I have 17kW of Tesla panels and three (3) Powerwalls and live in AZ (tons of solid solar producing hours). We downsized from a very large house to a 2000 sq. ft home and have about maxed out our capacity. My goal was to create a gas-station at home for our electrical vehicles.

We have two R1's (T and S) and I can add about 20% to each a day in the Summer and 33%+ per day outside of summer. Summer we have a higher load because of AC use. We went all mini-splits and our central AC is a back-up. Outside of summer we absolutely have a fuel station at home. Summer we can add power to our batteries, but this is not always sufficient. We pay $0.065 per kwH from 11pm to 5am, so that is affordable.

I just want a fuel station at home, it's my personal thing . You need to at least double your capacity if you want a true fuel station is my opinion. Sorry for the convuluted message....but I'm sure you get the picture.

I agree, my system alone does not keep up with Rivian's demand. After all, Rivian has a 135kW battery and my wall battery units are only 20kW.
So, there is a period every time I charge that I deplete my batteries and then tap off of the grid.
My solar system only helps a little and fortunately charge my wall batteries back to full when I don't charge. Luckily my electric bill varies between $60 to at times $120 per month. I live very comfortably. AC and an electric pool heater, both high consumption.
So I drive my Rivian daily for almost free, nothing. How many ICE truck can say that?

 

[shandel]

I have a similar setup with Tesla solar and two batteries. I am signed up for the net metering rate with the EV-2 plan like you, so that effectively allows me to charge whenever the rates are lowest and not worry about whether it's coming from solar directly or not. It all nets out. In fact, I wired up the charger so that it is hooked up to the main panel before the solar/battery, so it charges from the grid directly. There's really no point in having it charge from your Tesla batteries since the capacity in them is so small compared to the Rivian battery. And in the case of a power outage, I would want the Tesla house batteries to be reserved for charging the household and not used for charging the car.

 

[simoncellis]

I live in Bay Area with R1T, solar and battery. Best way to predict charging performance is to look annually. My 5.6 kW solar is guaranteed to produce 8MWh (actual last year was closer to 9MWh). My house used about 4MWh, leaving 4MWh for the truck. This @2 m/KWh = 8000 miles. A lot of my miles are trips where I use RAN and other fast chargers. With net metering, the sun, and 16kWh battery I do not think it matters much what time of day you change?

 

[Mike2325]

I wouldn't spend the money on the solar or batteries.
I have both and like my battery but the price per kwh through my power company ( live in Southern California, 2nd highest in the country to Hawaii) isn't paying off much.
I have a 20kwh battery and a 7.5 solar array. I figure it will pay off in 5 years they way I'm using it. ( we have 2 electric vehicles that we charge at home )
I burn my 20kwh battery nightly because we use ac daily from June to mid September, usually. It runs out around 730 and I start at 4 pm to peak shave. ( peak time is 4-9pm)
Our power costs us 46 cents a kwh, so I can make it a little more than halfway using battery with our ac going.
The only reason I got the battery was to peak shave, charging my car seems silly because I have load losses and battery degradation.
I usually charge the vehicles during the afternoon when there's plenty of solar ( from my neighbors, the power plants usually ramp down because of solar excess, for me this makes more sense to stay greenish )
Doesn't seem like getting solar will make much sense to you, and definitely battery wouldn't make much sense either.
Hopefully manufacturers will start making vehicle to grid available for your vehicle and you can load shed with your car eventually

 

[TeamDavid]

I wouldn't spend the money on the solar or batteries.
I have both and like my battery but the price per kwh through my power company ( live in Southern California, 2nd highest in the country to Hawaii) isn't paying off much.
I have a 20kwh battery and a 7.5 solar array. I figure it will pay off in 5 years they way I'm using it. ( we have 2 electric vehicles that we charge at home )
I burn my 20kwh battery nightly because we use ac daily from June to mid September, usually. It runs out around 730 and I start at 4 pm to peak shave. ( peak time is 4-9pm)
Our power costs us 46 cents a kwh, so I can make it a little more than halfway using battery with our ac going.
The only reason I got the battery was to peak shave, charging my car seems silly because I have load losses and battery degradation.
I usually charge the vehicles during the afternoon when there's plenty of solar ( from my neighbors, the power plants usually ramp down because of solar excess, for me this makes more sense to stay greenish )
Doesn't seem like getting solar will make much sense to you, and definitely battery wouldn't make much sense either.
Hopefully manufacturers will start making vehicle to grid available for your vehicle and you can load shed with your car eventually

Yeah the solar and batteries are mostly for being able to run the AC through peak if we need it, or on spare the air days. We are very conservative with our energy usage, so the addition of solar and batteries will let us relax on our self imposed restrictions. I just wanted to get a feel for how electric charging works into that equation. From what i've read above (thanks for all your responses) it's about what i thought would be the case.

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