Off-grid solar home needs upgrade for 2 Teslas

[Tony2]

Hi all, we are currently living off-grid in a earthship hybrid with a 3.4KW solar system which needs to be upgraded to 5 or 6KW to fulfill our home needs. We need your help in figuring out our upgrade because we are thinking of adding a Tesla Cybertruck in 2 to 3 years and then a Tesla model Y in 5 to 6 years.
So how many KW's should we design in our future upgrade. Again 5 to 6KW base need, and then 2 Teslas added over the next 2 to 6 years. We are retired and will driving approximately 12,000 miles a year combined with our Tesla's.

We appreciate any knowledge and ideas in our solar off-grid journey.

 

[Supervstech]

The answer depends greatly on your driving needs...

Solar isn’t realistic for charging a single Tesla if daily driving approaches the range of the car...

If range is 1/2 daily, still hard to implement with solar...

a single Tesla car is 85KWH the truck will likely be in the 150range... to be able to recharge the range overnight, you are going to need that much storage alone...

So... how much do you drive?

 

[Supervstech]

So, 1000 miles a month, roughly 33 miles a day... peanuts.

figure 100 miles a day average... that’s 50 miles a day between vehicles... or 1/5 bank capacity.

85 kw for the Y, 150 for the CT... you are getting the CT first, so 150/5 is 30KWh per night. The standard NEMA14/50 cord included will handle this load easily and you will need an additional 5KW solar to feed the bank during the day.

 

[Darkstar]

This fellow plans to power his entire home with a Cybertruck and solar panels:

https://www.electricbike.com/ive-got-the-power-using-the-cybertruck-to-power-my-off-grid-tiny-house/

 

[Tony2]

So, 1000 miles a month, roughly 33 miles a day... peanuts.

figure 100 miles a day average... that’s 50 miles a day between vehicles... or 1/5 bank capacity.

85 kw for the Y, 150 for the CT... you are getting the CT first, so 150/5 is 30KWh per night. The standard NEMA14/50 cord included will handle this load easily and you will need an additional 5KW solar to feed the bank during the day.

Thanks so much Supervstech for the feedback. It looks like we would upgrade our solar to 10KW system. Our average peak sun hours are 6, which means on an average day we should be get 60KWh a day. We are retired and only need to go to the next large town (180 miles round trip) to shop once a week. So the Cybertruck AWD (2 motor) 150KW with a range of 300 miles will only need less than a full charge once a week. Is that correct? And when we get the Y at 85KW we would be in even better shape.

We would probably charge the vehicles during the day while the sun is out, is that the best way to do it?

Many thanks, Tony

 

[Tony2]

This fellow plans to power his entire home with a Cybertruck and solar panels:

https://www.electricbike.com/ive-got-the-power-using-the-cybertruck-to-power-my-off-grid-tiny-house/

Thanks for sharing the article. We'll be using our Cybertruck for boondocking, it looks like it has a lot of potential, indeed.

 

[Tony2]

So, 1000 miles a month, roughly 33 miles a day... peanuts.

figure 100 miles a day average... that’s 50 miles a day between vehicles... or 1/5 bank capacity.

85 kw for the Y, 150 for the CT... you are getting the CT first, so 150/5 is 30KWh per night. The standard NEMA14/50 cord included will handle this load easily and you will need an additional 5KW solar to feed the bank during the day.

I will probably be adding 7KW of panels to our system which would make 10.5KW total. Having a CT if V2H becomes available with the CT would be an ideal solution for us as offgridders. What do you think that the chances of V2H will be by the time the CT is shipped? Thanks

 

[Ampster]

What do you think that the chances of V2H will be by the time the CT is shipped?

There were some erroneous reports that the charger in the Model 3 had bidirectional capabilities but that was not true. Musk is unpredicable but it does seem consistent with his long term mission but he would not let it cripple Powerwall sales. Perhaps with a bidirectional charge controller on Powerwall V? that would allow it to modulate car charging to follow solar production. A Powerwall doesn't make sense yet for off grid though.
As far as VTH using an extension cord there are workarounds. I am connecting some Anderson connectors to the 12 volt battery on my Teslas and then I can plug in a 1000 Watt inverter to run some things at my sisters house or if my own backup system has a glitch. Will did a video and the DC to DC converter can handle 200 Amps so that should work.

As far estimating how much capacity you would need to charge a Tesla I estimate 300 to 350 Watts per mile or 350 kWh per month if you drove 1000 miles a month. By the time the cyber truck rolls around there will probable be some interface where you can just plug in your EV and the controller will charge your EV with the available solar once your house batteries are full. One guy here is doing that with an Arduino and I have a current transformer that turns on my charging station at 2000 Watts when my solar hits 2000 Watts. It also turns off when solar production drops. It is crude but it works for now and demonstrates the concept.
BTW, I also have a deposit down on the Cyber truck.