Abstract: A method for testing at least one bypass diode in a photovoltaic system including at least one photovoltaic module that is in operation, the photovoltaic module includes at least one string of photovoltaic cells that are connected to a bypass diode dedicated to this string, the method includes: shading a portion of the cells of the string so as to cause a switch to bypass mode through the diode, this switch causing an increase in the temperature of the diode if the diode is in an operational state; measuring at least one temperature of the diode; and comparing the measured temperature with a threshold in order to deduce a state of the diode.