by MtnDon » Fri Oct 07, 2016 12:43 pm
IF it puts out a compatible voltage, 14 to 19 volts, it is completely safe. However, at 6 watts that is a half ampere and only if the sun is shining brightly on the panel. Maybe, maybe usable as a trickle, maintenance charge while sitting idle in storage. 6 watts will have virtually no ability to actually replace power used by lights, etc.
Do you know if the specs state that it has diodes to block current from draining the battery when the sun does not shine? Hopefully it does. If you have a multimeter you can confirm that it does not discharge the battery when the sun is gone.