System and Methods for Determining Characteristics of a Photovoltaic Panel

A method comprising:

• receiving auxiliary power for a controller from an auxiliary power circuit via one or more of first terminals and second terminals;
• wherein the controller is a controller of a power device of a string of serially connected power devices coupled to a power system controller, wherein the power device comprises:
• the first terminals connected to a corresponding photovoltaic panel;
• the second terminals serially connecting the power device in the string;
• a power converter connected to the first terminals and to the second terminals;
• and
• the controller;
• controlling, using the controller, the power converter to selectively enable and disable a reverse current to the corresponding photovoltaic panel using power provided from the power system controller to the power devices via the string;
• and
• characterizing the corresponding photovoltaic panel based on the reverse current.