I dont understand what you are asking in this post. During the day, if the sun is shining, the PV system will generate power and likely provide enough energy to run your home and power your AC, during the middle of the day.

That doesnt have anything to do with “2-3 days backup” though. If your AC runs at 3.2 kW when its running, and you need to use it during the evening, its pretty clear to see that it alone will completely drain your powerwalls in 4 hours run time. That doesnt count the rest of your house.

This is why I said “there is no such thing” as 2-3 days backup guaranteed”. If the powerwall only backs up lights and a fridge, then you might get a day or two. You are talking about AC though.

You also have “97%” of your CURRENT usage covered with that 9.6kW system, which does not include the power you are going to use for your car (and the fact that both you and anyone else in your home will expect to be able to run the AC more etc.

If you buy solar, and then start turning the AC off etc, unless you are single, you will be in for some HARD conversations about “why are you still doing that, we bought solar, right? “What did we get solar for if we cant even run the AC as much as we used to before we got it?” Once you get solar and any app etc that allows you to see usage in real time, along with driving your car and expecting to have that usage covered with solar (and it wont be, because your current system is only specced to cover your current usage) and you are setting yourself up for a pretty huge disappointment.

Just from what you posted, its pretty clear to me that 9.6kW Solar is not the appropriate size for you, at least based on what you have posted. You need a larger PV system, and if you want to only buy 1 powerwall, then you need to come to grips with the fact that you will not be running your AC for longer than a few hours (probably a couple) if you are off the grid, or not back up the AC at all (which would be an even more difficult conversation if you had a power outage and your significant other started wondering why the house is so hot and you cant turn on the AC).

I love my powerwalls, I really do. with that being said, if I was in the situation you seem to be describing, I would probably up the PV system size and ditch the powerwall for “later”. Its going to be much more important to get enough solar, because you will not be adding onto it later. No one is going to “just add panels” so if you want to add later, it will be an entirely new system on the other parts of the roof on your house.

Use the money for the powerwall for more PV (solar) instead, if the budget is not flexible. If you dont, you are likely to be disappointed in the end result of spending money on your PV, yet your electric bill going up as well because of additional AC usage and driving your new EV.