Pardon my ignorance, but I have yet to enter the world of electric vehicles and know little about charging. I'm patiently waiting for the model 3. It seems like the synergy Elon spoke about with these systems would mean that the cars could ideally charge overnight from the stored solar energy captured during the day. I may not be doing the math correctly, but is this even possible with only one or two powerwalls, if one is planning to use them for the house as well?
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Powerwall and car charging
- Thread starter BagheeraNY
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- Powerwall Tesla Energy
Xminus6
Member
Purely depends on how much you're willing to spend on batteries. I drive 42 miles a day on my regular commute and use about 15-16KwH per day for the commute. That would require 2 Powerwalls. My house has crazy high consumption, but we also have solar. So let's say you're fairly average and use 30KwH per day for your house. Add in the 15KwH for the car and you've got a daily usage of 6 Powerwalls.
Now you've got to buy enough panels to generate 45KwH per day to charge those batteries. That's a pretty large system. My highest generation day during the middle of June was just over 100KwH, but now that we're entering winter I average around 35. So the seasonality will affect your generation greatly. If you just want to average it all out and find a sweet spot where you're keeping your utility energy consumption low enough to keep you at cheap prices it seems much more doable. Elon even mentions that in the presentation. It's not really financially feasible or practical to go completely off-grid unless you need to.
Now you've got to buy enough panels to generate 45KwH per day to charge those batteries. That's a pretty large system. My highest generation day during the middle of June was just over 100KwH, but now that we're entering winter I average around 35. So the seasonality will affect your generation greatly. If you just want to average it all out and find a sweet spot where you're keeping your utility energy consumption low enough to keep you at cheap prices it seems much more doable. Elon even mentions that in the presentation. It's not really financially feasible or practical to go completely off-grid unless you need to.
JSkrehot
Member
I first began writing this with a simple answer or no, however, after looking at my energy consumption on PG&E, I'm not yet sure. I am also waiting on my Model 3 (will be my first electric vehicle), live 40 min from Fremont Factory, so hope it is sooner, ha. I just did a self install, home solar install of a 6.12 kWh system from gogreensolar.com with a 7600 series Solar Edge Inverter (compatible with Powerwall if in the future I choose to buy) so that I can expand my system if needed after I get my Model 3 (have free charging at my work, so we'll see). If you drive like 40 miles per day and you use a Nema 14-50 outlet with the provided charger your Model 3, S, or X comes with (charges 29 miles/hour), you use like 13.74 kWh of power per day to charge your vehicle. A single Powerwall 2.0 is a 14 kWh battery, I've only had my solar system on since 10/5/16 and have had days where I produce 19 kWh in excess and days where I use 16 kWh from the grid, depending on the amount of clouds and sunshine. We'll see what it all computes out to after 12 months with Net Metering, however, my system should produce 109% of my entire usage from a year ago, so while it doesn't seem to make sense now, it might after I get my Model 3, but again, I get free charging at work and work four 8 hour shifts, so a lot of free energy with less charging needed at home.
Waiting4M3
Active Member
That's a good point to have every house be completely self-sufficient, which means the house itself can have enough energy generation to cover the worst case scenario. This would mean that most time you have excess energy generation that you're not using. If you're completely off the grid then those energy is not going to a useful destination, unless if you use tricks like H2V then V2G elsewhere.
Thanks everyone for clarifying. I'm 2283 miles from the Fremont factory, so I'll be waiting a bit longer than you for the model 3 delivery. It'll be worth the wait though! Hopefully some more details about the solar roof will be out by then. The integrated solution would be pretty slick, even if it doesn't completely separate me from the grid.
