The most people charge thier computer or smart phone frequently, and try to keep in full charge status.

They have to understand that is the worst habit to use a lithium chemistry.

When keep the high charge status over long time, battery degradation is happening.

Will lost capacity permanently, this damage can be increased with the temperature of battery (device).

This is why no one recommend do not keep charging all the time, to reduce the average status of charge.

I have 10kWh (51.2V, 200Ah) battery pack already.

But, it is not enough to back-up 2-3 days.

So, I have ordered custom battery pack module (total $6,000 include delivery/bus-bar box).

Each battery pack have 5kWh (51.2V, 100Ah) capacity.

Total 30kWh will enough

     2 days     without 0 solar production in winter season

     3 days     with 50% solar production in winter season

     unlimited  with 100% solar production in winter season

My power usage is around 12~16kWh in winter,  

The full solar production is just 10~13kWh in winter, I have to install an extra panels to support full power demand. and planing on this summer

     1.4kWAC panel for grid-tie, expected 2~3kWh extra in winter season

     0.7kWDC panel for battery back-up, expected 1kWh exra in winter season

Basically, no need to worry in spring/fall/summer, solar panel can generate more than a day amount.

just need a night back-up

Install Schneider XW Pro (6848 Inverter/Charger) for an emergency back-up at home.

I have finished in 2020, but, Just found an installation photo.

I have add 2/3" Plywood on the wall to hold the inverter, it is so heavy (137lb),

And, prepared back-feed to main breaker panel for whole house power.

Inverter / Conduit Box / Gateway / SCP / Extra electric parts (wire / breaker / interlock / conduit / .....),

Total cost is around $5,000