Perform a continuity check on the panel, to verify the problem is with the panel. Disconnect the solar panel’s plug, located at the end of the panel’s wiring harness.
Set a multimeter to the 12-volt DC “ohm” setting. On some meters the ohm setting will be marked as “1X.”
Touch either of the meter’s probes to either the red or black terminal on the solar panel’s plug. Touch the meter’s other probe to the other terminal on the panel's plug.
Check the meter; any reading indicates the problem is not with the panel. If there is no reading on the meter, check each individual panel cell.
Remove the cover of the solar panel with a screwdriver. Locate the two terminals on each individual photovoltaic cell. Repeat the continuity test on each cell, beginning with the cell closest to the panel’s plug and testing each cell in the panel until the faulty cell is located.