What battery size fits inside the FX-5 cabinet, and what is the maximum Ah rating the charger can support?

The FX-5 cabinet can accommodate up to two 10 Ah batteries internally (Page 1, 6) [1].

The panel's charger supports a maximum charging capacity of 24 Ah (Page 109) [1].

If batteries larger than 10 Ah are required, an external battery cabinet must be used (Page 6) [1].