It's really more like "as long as you're above the voltage of the battery plus your blocking diode (if any) you're OK".
Voltage is limited by the voltage of the load in a battery-charging operation. Current from each panel is limited by the lower of:
- The rate photons hit the least-illuminated cell / paralleled cell group of the panel's series string.
- The current that causes the voltage drop in the panel resistance plus wiring resistance to equal the difference between the panel's open circuit voltage (less drop in the blocking diode if any) and the battery voltage.
So on hot days the current will start dropping off at a lower temperature for the low-voltage panels than for the high-volt ones. But you won't run into any problem other than low charging rate.