Charge from Powerwall avoiding the grid.

[endlessknot]

Hi all,

We have Tesla Solar Panels and 1 Tesla Powerwall.

We received our Model Y on Sep 11, 2021. We had ordered it on May 28, 2021.

My goal is to charge the Model Y from Powerwall avoiding the grid.

After some research, I changed "Charge Current" to "20 Amps" and scheduled Charge Start at "12:30" daily. I connect the charger to the car during the day.

Here is the picture from Model Y.




The main purpose of getting the Tesla Powerwall was for charging Model Y.

Please share your thoughts.

Thank you.

 

[endlessknot]

Attached is picture of charge and schedule.

 

[wkramer28451]

Charging your Y using solar panels and the powerwall is a nice thought. The only problem is that you will never pay for the solar panels and powerwall in the lifetime of the solar panels and powerwall or the car. Until the cost of both come down dramatically it's only throwing money away.

I'll add that I've had solar panels on my last and current home and they will never pay for themselves in electricity savings.

 

[boulder.dude]

I’ve been wondering — can Powerwall charge the car “directly,” I.e. DC-to-DC, hopefully avoiding transformer losses?

 

[Cares]

Charging your Y using solar panels and the powerwall is a nice thought. The only problem is that you will never pay for the solar panels and powerwall in the lifetime of the solar panels and powerwall or the car. Until the cost of both come down dramatically it's only throwing money away.

I'll add that I've had solar panels on my last and current home and they will never pay for themselves in electricity savings.

I don't know how you do your math in which it never pays off. That would mean it literally never makes sense to get solar. My solar is breakeven in 6 years. My previous home it was 8 years.

 

[arnolddeleon]

Hi all,

We have Tesla Solar Panels and 1 Tesla Powerwall.

We received our Model Y on Sep 11, 2021. We had ordered it on May 28, 2021.

My goal is to charge the Model Y from Powerwall avoiding the grid.

After some research, I changed "Charge Current" to "20 Amps" and scheduled Charge Start at "12:30" daily. I connect the charger to the car during the day.

Here is the picture from Model Y.




The main purpose of getting the Tesla Powerwall was for charging Model Y.

Please share your thoughts.

Thank you.

Are you looking for advice? Validation?

Why do you want to avoid the grid? To save money? You hate your utility? You think it is greener?

How many miles do you drive? How hard do you drive? How much electrical energy do you consume outside of your car? How big is your photovoltaic system?

Do you have time of use rates? Do you have a net metering agreement?

Some random thoughts. Energy going through the Powerwall incurs a roughly 10% conversion loss. You have about 13 kWh of usable energy in a Powerwall. The battery in a Model Y is approximately 74 kWh. Rated wh/mile is 279. For estimating purposes I would use 3 miles for every kWh as measured from the plug.

 

[wkramer28451]

I don't know how you do your math in which it never pays off. That would mean it literally never makes sense to get solar. My solar is breakeven in 6 years. My previous home it was 8 years.

It all depends on where you live. Electricity in my area in NC costs 10.5 cents per KWH. With net metering it costs 6 cents per KWH at night. At those rates your solar panels and powerwall would be ready to be replaced before they ever paid for themselves.

 

[scottycs]

100%. Im in NC and would love to get solar, but its a BAD investment.

It all depends on where you live. Electricity in my area in NC costs 10.5 cents per KWH. With net metering it costs 6 cents per KWH at night. At those rates your solar panels and powerwall would be ready to be replaced before they ever paid for themselves.

 

[Madsen203]

Solar paid for itself in 4.5 years here. Got a 4.7kw system for 10.5k after rebate. In sunny Bay Area, we are generating 8+ mwh per year. At .34c per kWh that pays off pretty quick.

 

[Rocky_H]

I don't know how you do your math in which it never pays off.

...says the guy in Orange County to the guy in North Carolina.

It all depends on where you live. Electricity in my area in NC costs 10.5 cents per KWH. With net metering it costs 6 cents per KWH at night. At those rates your solar panels and powerwall would be ready to be replaced before they ever paid for themselves.

100%. Im in NC and would love to get solar, but its a BAD investment.

Yeah, I wanted to do solar panels for a long time, like 15 years, but I kept watching their prices come down and checking the analysis versus our 8 cents per kWh with no delivery fees, and it just wasn't working. It finally got kind of maybe tolerable, so we did it a few years ago, but I'm still thinking it's going to be somewhere around 10 to 15 years for the payoff.

 

[v8eater]

Hi all,

We have Tesla Solar Panels and 1 Tesla Powerwall.

We received our Model Y on Sep 11, 2021. We had ordered it on May 28, 2021.

My goal is to charge the Model Y from Powerwall avoiding the grid.

After some research, I changed "Charge Current" to "20 Amps" and scheduled Charge Start at "12:30" daily. I connect the charger to the car during the day.

Here is the picture from Model Y.




The main purpose of getting the Tesla Powerwall was for charging Model Y.

Please share your thoughts.

Thank you.

If you live in LA, like your profile states, it doesn't make any sense to charge the car using the powerwall. If I'm not mistaken, you have super off peak rates which you could use to charge the car. Use the energy stored in your power wall to supplement your home usage during peak rate times. Ideally, you would charge the power wall every morning then use the excess solar in your home vice exporting it to the grid. That is unless you have a favorable sell back credit rate.

 

[v8eater]

...says the guy in Orange County to the guy in North Carolina.


Yeah, I wanted to do solar panels for a long time, like 15 years, but I kept watching their prices come down and checking the analysis versus our 8 cents per kWh with no delivery fees, and it just wasn't working. It finally got kind of maybe tolerable, so we did it a few years ago, but I'm still thinking it's going to be somewhere around 10 to 15 years for the payoff.

8 cents per KwH is a really good rate. I only pay 10 so my ROI would be slightly faster. That isn't the main reason for wanting solar, it's the backup power when the grid is out. Alas, I move every two years with the military so I'll have to wait. Wasn't willing to spend the money on solar and power wall for a rental property.

 

[wkramer28451]

8 cents per KwH is a really good rate. I only pay 10 so my ROI would be slightly faster. That isn't the main reason for wanting solar, it's the backup power when the grid is out. Alas, I move every two years with the military so I'll have to wait. Wasn't willing to spend the money on solar and power wall for a rental property.

Not good when grid is down unless you spend a fortune on batteries powerwall or otherwise. Most would never get the ROI in their lifetime in that situation. In most situations people do solar to make themselves feel good since like I said many never see the ROI.

And if your doing it in the state with the second highest utility rates, California, they will probably pass a law that says you have to share your power when the grid is down with the less fortunate.

 

[Drlev]

Bear in mind one Powerwall can only output 5 kw continuously. If you charge at an amperage that exceeds that, you will be drawing from the grid.

 

[frankvb]

I’ve been wondering — can Powerwall charge the car “directly,” I.e. DC-to-DC, hopefully avoiding transformer losses?

Pretty sure it's not possible currently - however it won't as simple as just connecting the powerwall to the vehicle with a DC interface. The battery voltage in the car won't be the same as that of that powerwall batteries, which means you still have to so some DC voltage conversion.

E.g. the powerwall battery might be at 400 V (making this up, I don't know the details of that hardware) but the vehicle battery might be down to 350V. Connecting those directly would cause a massive inflow current likely damaging both batteries.

If there was hardware to do this DC-DC conversion, it would indeed be more efficient thought than going via the 240V route.

 

[JHCCAZ]

...they will probably pass a law that says you have to share your power when the grid is down with the less fortunate.

The less-fortunate being anyone who chose to spend none of their own fortune on being prepared for unfortunate events.

 

[wkramer28451]

The less-fortunate being anyone who chose to spend none of their own fortune on being prepared for unfortunate events.

The majority of people don't have the spare money to buy solar. It's still an upper financial class thing. Especially in California which has the highest percentage of people living in poverty than any other state.

 

[Cares]

The majority of people don't have the spare money to buy solar. It's still an upper financial class thing. Especially in California which has the highest percentage of people living in poverty than any other state.

Where did you randomly pull that stat out of? I guarantee you California is not even in the top 10 list of states for percentage of those living in poverty.

Edit: Yep I was right Poverty Rate By State 2021

 

[v8eater]

The majority of people don't have the spare money to buy solar. It's still an upper financial class thing. Especially in California which has the highest percentage of people living in poverty than any other state.

Of the states where investment in solar makes the most sense, CA is either number 1 or tied with HI. If you plan on living in CA for a while, solar is the only way to go. That is AFTER you invest in less expensive ways to lower your energy usage.

 

[mrwug]

Where did you randomly pull that stat out of? I guarantee you California is not even in the top 10 list of states for percentage of those living in poverty.

Edit: Yep I was right Poverty Rate By State 2021

Yes and no. Census poverty stats do not adjust for regional cost of living.

Poverty thresholds, the minimum income needed to avoid poverty, are updated annually for inflation using the Consumer Price Index, and adjusted for family size, composition, and age of householder.

OPM thresholds do not vary geographically.* In 2016, the OPM poverty threshold for a family of four was $24,339.

If 9% of Californians were trying to get by on less than $25K in 2016, I'd say that a much larger percentage lacks capital to buy solar. Assuming you have the cash, you're not in a position to install solar on a property that you don't own. California trails only New York in lowest home ownership rates in the country.