To be installed in front of the inverter and at the output of the panels to protect both the panels and the inverter.
Once a surge or spike is detected which exceeds the clamping voltage appears the MOV reacts conducting the excess voltage to ground. The MOV segment will continue to do this until it has reached its life expectancy and expires. The green indicator tab on the front of the SPD will remain green until the MOV expires at which time the indication tab will change to RED. If this should occur we recommend you consider changing the SPD ASAP as the SPD has expired and protection no longer exists. The expiration of the MOV component will also activate the alarm circuit. As these units are modular, all you need to replace is the module.