PID has been typically studied in p-type based Si PV modules (1-8). Metal ions, such as Na, which are involved in the soda lime front cover glass, and migrate toward the Si cell by high-voltage stress, are considered to cause PID (9-13). decrease in the shunt resistance of modules owing to influence of Na on p-n junction seems to be main reason leading to PID in p-type Si PV modules (Shunting type mechanism (12))