Here are 2 important reminders for sizing MPPT controllers:
Tip #1 PV panel Vmp > controller’s minimum solar input voltage.
The panel voltage at maximum power (Vmp) should be higher than the controller’s minimum solar input voltage specification. For 12V systems, this is typically 17V. For 24V systems, this is typically 34V.
Tip #2 Don’t pair one 60 cell panel to a 24V battery bank.
Using one 60 cell panel to charge a 24V battery bank is not recommended. The Vmp is typically too low to charge the batteries sufficiently.