LFP Battery Banks can certainly be scaled up in size (Bank Capacity) to huge, even 300kWh if you are obscenely wealthy. But then you have to charge that and manage it and that is yet another huge ball of wax. Again see Obscenely Wealthy and not necessarily smart enough to know better.
3-Phase appliances ? Really ?? North America 240VAC is Split-Phase and is common/typical in any North American Home but NOT 3-Phase which usually goes to commercial industrial. Please provide a Make Model of a 3-Phase appliance you have, I gotta see this.
You are looking at an EV Battery that may be 300-600 VDC and so your thinking that is apples to apples but it is not, quite another beast. Some EV's allow for DC Fast Charge but that is NOT residential and likely will never be (unless you are crazy rich). Level-2 Charging generally tops out at 240VAC/50A but most are throttled a tad lower, depending on brand & model and EV type of course.
50A@240VAC = 12,000 Watts
48VDC @ 12,000W = 250A (Uncorrected for inneficiencies)
- 1X 48VDC/280AH Battery Pack = 14.3kWh or 14,336 Watt Hours.
-- This consists of 16 LFP Cells in Series Only.
One company Example (I have no affiliation or anything with these folk) which is based in PA, USA builds these Battery Systems which you may wish to look at for a "Commercial" example
https://www.fortresspower.com/products/evault-max-18-5kwh-lifepo-battery/
ClipperCreek EV Chargers (Made in USA) has their Big
CS-100, 70/80 Amp (Selectable) EVSE, 240V, with 25 ft cable which pulls a MAX of 100A from 208-240VAC and only Split-Phase.
Grab your Power bills for the past 12 months. Take a look at the kWh consumed every month. Grab the two Highest & two Lowest bills (in kwh consumption) so now you will know what your "current" usage is in reality and when that occurs. Depending on your billing system, it may or may not show a "Daily Average" which you can figure out easily enough.
- Once you KNOW your Highest Use Time and the amount of kWh used during that period, THAT is your target for "Daily Storage - for use".
- Then figure out how many days of reserved/stored power you want for bad weather periods etc. Most folks use 3 Days for calculating their reserve.
- Next you can size the Battery Bank that would satisfy the requirements...
- Next you have to work out how much Solar Input will be required to charge that battery bank on the Lowest Sun Hour Days in your locale.
- Then at the same time, the sizing of the Inverter System(s) to support the household demands.
Please understand that Energy Conservation is FAR CHEAPER than Generation and storage !
Unload the Fridge you inherited from Grandma - It's a Power PIG like many older appliances & devices. Find where you can improve on energy efficiency for your home & the appliances/devices within. Old Hot Water Tanks (like leaving a gas car idling in the driveway all day long because "maybe" you may need to drive somewhere = very stupid indeed). Think, 3000W+ elements running 15 minutes of every hour just to keep it warm... On-Demand is good solid reliable tech and NOT NEW and not wasting power when not needed....
Bottom Line:
Figure out your Real & Actual Usage, consider what can be replaced (energy saving wise).
Then come up with a Plan to accommodate your "needs" NEXT add in your "wants" and then the "Would likes" and do the math to re-ground self. Make a Revised REALISTIC plan and then start the shopping process. DO NOT BUY ANYTHING UNTIL YOU HAVE A FIRM PLAN IN HAND ! Because without a Plan is a Plan to Fail and it can be very costly & quickly too.
FYI, unlike Lead Acid/AGM and such, with Lithium Batteries, you can ADD PACKS OVER TIME as money comes available. You do NOT have to buy the whole 12 course meal at once, like the old days. LFP does not age/degrade like Lead and each pack is its own entity. MANY have the idea / notion they have to buy everything at once which is Terribly Wrong. It just has to be incorporated into the plan and the system foundation built to support expansion.
Hope it helps, Good Luck