Anyone going fully off grid?

[TheTalkingMule]

You'll likely be able to get $2-$3 per Watt installed for solar, less if you do some ground mounted yourself. Powerwall 2 is about $7k installed and you'd likely need 2-4 of them to go off grid. So just a guess would be $32k after tax credit if your needs are modest.

All this would depend on your solar potential in winter and the design of your array. You could also install a small wind turbine or two, though I know nothing about the tech or cost.

 

[commasign]

Yes. Have tested it a few times. The solar PV system charges the batteries even when the grid is out.

Today is a good day. Crazy wind. Grid out several times for several hours already. But good sunlight. Confirmed that the Tesla system is able to wake up the solar inverters to charge the battery and power the house (including charging the Model S).

 

[daniel]

Cool!

 

[Nuclear Fusion]

Today is a good day. Crazy wind. Grid out several times for several hours already. But good sunlight. Confirmed that the Tesla system is able to wake up the solar inverters to charge the battery and power the house (including charging the Model S).
View attachment 267048

How does it go in Winter?

 

[commasign]

How does it go in Winter?

It’s pretty much winter here now. December and January are the worst solar months.

 

[Nuclear Fusion]

It’s pretty much winter here now. December and January are the worst solar months.

Wow! 4.5kw is very low for a day’s use. How do you use so little?

 

[abasile]

Wow! 4.5kw is very low for a day’s use. How do you use so little?

That's the instantaneous power usage, presumably, not the day's total energy use which would be measured in kWh.

 

[commasign]

Wow! 4.5kw is very low for a day’s use. How do you use so little?

4.5kW, not kWh. Baseline load is about 1.1kW. Peak as high as 15kW when the oven is on and the cars are charging. Our house and cars can use over 100kWh per day in the summer.

 

[Mastruck]

Yeah, it was load based. Yeah, in a nuclear war scenario, we'll just hang our clothes on a line.

If connected to grid, the surplus PV generation just goes to the grid. If grid is out, the Powerwall system apparently commands the PV inverters to throttle down or stop production once the battery is full. Haven't tried this yet though. In an extended outage we'll just schedule our EV's to charge during the daytime to maximize production.

We are getting ready to do a Powerwall 2 install on our house with an existing PV system. Tesla is recommending 4 PW2s for whole home backup.

We live in AZ and have 2 ACs.
We also have 3 EV chargers.
Our total annual power consumption is around 34Mwhrs
Our total annual solar generation is around 35Mwhrs (70 panel Enphase micro-inverter system)

Tesla doesn’t provide a ton of backup with their recommendations and I am looking for feedback as to whether this sounds right. It sounds like you have less power demand than we do and they set you up with partial home backup using 4 PWs. Perhaps I am OK because I am generating more solar power?

I would much rather work with a local contractor to develop my proposal and do the install, but not really an option if you want to use Powerwalls. Very hard to do this with confidence with Tesla’s current support strategy. I suppose what they are doing is fine while they are supply constrained though.

 

[commasign]

Tesla doesn’t provide a ton of backup with their recommendations and I am looking for feedback as to whether this sounds right. It sounds like you have less power demand than we do and they set you up with partial home backup using 4 PWs. Perhaps I am OK because I am generating more solar power?

I think the Tesla calculator is based on load. 4 powerwalls seems in the right ballpark for 2 AC units and 3 EV chargers. The way I looked at it is my house and cars use about 100kWh per day, so 50kWh of backup batteries should be fine to cover things when the sun is down. I was able to go off grid for a month with my setup.

 

[1100MCM]

Today is a good day. Crazy wind. Grid out several times for several hours already. But good sunlight. Confirmed that the Tesla system is able to wake up the solar inverters to charge the battery and power the house (including charging the Model S).
View attachment 267048

I’ve had 2 Powerwalls installed for a few weeks now and I threw the main breaker switch off and the solar is still generating and charging the batteries. All my individual home breakers for all home loads were relocated to a new panel and the original main panel was left in place with only the 200 amp main breaker switch.