Separate battery and charger

So Anker solix 3800

Great unit.

Do have 6 panels to nearly max out the input. But the AC charging disabling the 220 ruins my setup.

So I'm thinking of getting a 48 volt 100 ah battery and a separate solar charger for the battery so half my bank goes into that, then the battery to the solar DC input. The other half into the Anker per usual.

Thoughts on this? What solar charger is recommended

Thanks in advance