A single 3.5-meter block could hold 10kWh of energy, and power a house for a day
That's... not a lot of energy; can use it up doing like 2 loads of laundry if you have an electric dryer, or running a central A/C for a few hours. (let alone charging an EV, where you can burn through it in a bit over an hour to add maybe 15% or so)
4 would keep me powered most every day and night, with just my panels (8kwh max supply).
If I had in the range of 8 power walls, I could completely disconnect from grid supply and I would effectively never run have to concern myself in everything but the most extreme of weather circumstances. My local supplier has basically garbage policies around me giving back to the grid, and I have to pay a ridiculous connection fee.
I've got a friend who has convinced me to let him take apart my gen 1 leaf for the battery, which should give me an additional 24 ish kwh storage. I produce plenty of electricity during the day. I just need places to put it.
I've only done solar + battery setups on RVs and found 8kWh to be the probably the minimum if you have to run the AC at 100% duty cycle. Realistically at night that probably won't happen but I haven't had a chance to test the current one where I'll actually he doing that with a kill-a-watt to get a real world number.