Victron SmartSolar MPPT 75/15

You'll also need

Add a VE.Direct cable to a Cerbo GX MK2 if you want it on the GX. SmartSolar also has Bluetooth for the Victron app — you do not need a VE.Direct Bluetooth dongle.

SmartSolar MPPT 75/15 for small 12/24V arrays up to 220W at 12V (440W at 24V). 75V PV max, 15A charge, built-in Bluetooth, load output, and VE.Direct. Ultra-fast MPPT for changing light.