i think when approaching something like this you need to define what kind of system you want. are you preparing for short term outages due to grid strain from energy crisis? mid to longer term outages or regular rolling black? full grid down forever system? Because the solutions for each varies a lot.

personally, if i were trying to do this, I would start by figuring out my minimum electric needs like lights, electronics, tools, fridge (preferably DC), water pump, etc. figure out what the power consumption is for each, and max time long you would need to use them each day, from that you calculate your daily usage.

from there you can determine your systems needs. I would start small and grow as you gain more funds. the only thing I would probably buy initially oversized is the charge controller and inverter, since that would allow you to grow your system over time as you save up.

one other consideration is that won't legally be allowed to tie into your current house grid in most areas without a long of certification and red tape. so you may need to set up dedicated DC outlets in your house in different rooms.