I have had Strobl 2-panel units on a couple of gliders.
Even using SLA batteries, with the glider tied down outside overnight between flights I could keep the batteries charged on a panel which had no VGA display.
Using LiFePO4 batteries the 2-panel system will keep the batteries charged. That panel was perhaps "full monty", having com, txp, vario, VGA, flarm.
Interestingly, leaving the ClearNav on and removing the batteries, in full sun the 2-panel Strobl rig would keep the CN running if on minimum brightness.
That glider had the Strobl charger on the avionics bus, so whatever battery was selected was being charged.
Strobl also sells a dual battery charger.
Jim