I got myself a 13W solar powered USB charger which works fine. My goal is to add a super capacitor based buffer between the charger and the device under charge, to "survive" small clouds passing. (as the voltage drops, charging switches to low current mode, and takes time to switch back).
My initial plan is to have two inputs, a "capacitor charging" input (with current limiting power resistors) and an "operational input" for the actual charging. The USB charger would be separated with diodes from the supercaps on both inputs, that will drop the capacitor voltage to about 4.6V (voltage could be monitored on the voltage meter during "pre-charging"). The boost converter input would be this 4.6V, output ~5.1V. Maybe to 5.3V to compensate the fuse drop, I'm not sure about this yet.
Is this sounds OK for safe operation?