Everyone is a Tesla fan, but it's just a name, not a "fits-all solution" problems I see here:
1. You have not discussed your current situation - starting from scratch... already have solar? what product? Buying from an installer (definitely if it's Tesla), DIY kind of guy, or "you know someone"?
2. Off-grid means you need to size according to your worst day(s) of the year, there are probably days when you use 6kw... or 20kw.
Do you have room for 20kw of panels?.... size bigger for bad weather. 2nd the Emporia ASAP - you need to know granular hourly consumption in the winter.
3. Unless you live in a tiny home w\ 90% gas appliances and very little electric, 2x powerwalls aint enough.
4. Batteries are not like buckets of water, 5 gallons in the bucket is not 5 gallons usable out, they are more like cars, press the pedal harder, get 2x less miles, actual KWH varies by SOC / amperage / temperature... you wont get 13kw out of a powerwall. And the sun aint as reliable as your utility co.
5. Bad weather= less PV power, but you inherently tend to use more power, people stay indoors more, use appliances and heating more (you heat with gas?).
6. The term "permanent off-grid" is for very few people - Tesla is a pretty ribbon-wrapped box for people that dont want to get their hands dirty - that is NOT the off-grid crowd. Your consumption does sound low, but what you're saying is you want to become your own Utility company and assume all the liabilities and maintenance of that, the day will come when you will get your hands dirty, having power is not a trivial thing - you can do without for a day, but eventually time runs out and it's a MUST.
7. You would never charge an EV on 2 Powerwalls (+home). In 5-10 years you wont buy an EV?
I know people that have gone down that path, bought 2 powerwalls thinking "wow $50k out the door and I have a LOT of power".... only to find out it's not... then adding an EV in a couple years and finding out they need a huge expansion, and just small expansion is at a huge $$ premium.
What do you do when it's not enough? some say - "gas generator" (now you're buying/maintaining an $8-10k genset?) This endeavor will definitely cost way more than just paying the old utility company. Unless you do what previous commenters did and go big / go diy. You think you can slide by on 1 - get 2 (you will need 3-4 soon), plan for the near future.
Last question - who is going to put it in and maintain it (nothing lasts forever), if it is you - great, you will know what you have and possibly be equipped to service it faster than most solar companies.
If it is not you - your utility company just became some expensive solar installer that has probably installed 5,000 enphase systems - and then there's you - the one of 5 guys they *tried* to put off-grid... You can't really choose the "best product" (you here asking for advice on best option), you are at the mercy of what they know and sell. hmmm wonder how long that relationship will last and at what cost. I hear horror stories all the time about "my solar installer's dodging my calls for months while my system is under-performing or down". Then it's "I'm on my 3rd solar installer and they dont answer when I stomp my foot."
Even if you are a DIY kind of guy, you are still going to need some sort of *reliable* occasional support , call a place like Current Connected or Watts247 and ask them for a quality solution (something more robust than the typical guy wanting hybrid grid assisted... it probably wont be a Growatt/EG4). Personally I like Midnite Solar's MN15 inverter (you dont need that much inverter at 500kwh...until EV), and their Powerflo 16kw battery, they use grade A cells for long life, temp controlled with proper heating/cooling, and a real fire suppressant, while others advertise fire suppressor system, but they are just closing vents on the case, it's a clean well integrated system. You could buy 2-3 of those batteries for the price of 1 powerwall. Watts NHX inverter is similar to the Midnite. If you DIY (R&D) your own battery you can buy 7-8 for cost of PW3, (you plan to learn all the ins/outs and become your own battery support line), use big 280-300ah cells, Go to Docan Energy for a DIY 15kw enclosure kit with a JK BMS, they have a USA warehouse, usually very responsive, or one of these is maybe a better product, but not local:
(BE SAFE when messing with high amp power!!!)
Finding someone to put these "unicorn solar systems" in is difficult (thus DIY forum?), the mind-set of most solar installers is contrary to off-grid. .. The Tesla dealer network sounds tempting as a standard supported solution, but the dealers that "get it" are few and far. Too often I see Powerwalls paired with enphase (turning 13kw in to 10kw) - walk away if they mention enphase or any bs about "single point of failure" - get a robust inverter and separate batteries, if you're scared of single point of failure, get a spare cheapy inverter like a Growatt, they will produce more power on the days you *need* it than any enphase/powerwall combo.
