A procedure for detecting a fault or several faults of a photovoltaic system, comprising the steps of: - performing a measurement on the photovoltaic system to determine a plurality (A) of K pairs of values A = V j system , I j system , each pair associating a voltage (V) with a current (I), where j = 1...K - determining a set of indicators from the K pairs of values measured on the photovoltaic system, - comparing the set of indicators originating from the photovoltaic system with a plurality of N sets each comprising the same indicators, each of the N sets being characteristic of a single type of known fault, - determining the fault or faults depending on the result of the comparison, wherein the determination of each set of indicators comprises the following steps: - providing a plurality of K pairs of values, each pair associating a voltage with a current and originating from the system to be characterised or from a system with a known fault A by A = V j system , I j system and - providing a plurality of K pairs of values from a fault-free system B = V j fault free I j fault free where j = 1...K - determining at least one plurality of intermediate pairs from a first plurality C, a second plurality D and a third plurality E where C = V j f fault free , I j fault free I SC system I SC fault − free D = V j fault free V OC system V OC fault free , I j fault free E = V j fault free V OC system V OC fault free , I j fault free I SC system I SC fault free where V OC represents the open circuit voltage and I SC the short-circuit current of the system, - establishing, according to the determined plurality, the set of indicators based on a deviation between the pluralities D and B and/or between the pluralities C and B and/or between the pluralities E and A. - performing a measurement on the photovoltaic system to determine a plurality (A) of K pairs of values A = V j system , I j system , each pair associating a voltage (V) with a current (I), where j = 1...K - determining a set of indicators from the K pairs of values measured on the photovoltaic system, - comparing the set of indicators originating from the photovoltaic system with a plurality of N sets each comprising the same indicators, each of the N sets being characteristic of a single type of known fault, - determining the fault or faults depending on the result of the comparison, - providing a plurality of K pairs of values, each pair associating a voltage with a current and originating from the system to be characterised or from a system with a known fault A by A = V j system , I j system and - providing a plurality of K pairs of values from a fault-free system B = V j fault free I j fault free where j = 1...K - determining at least one plurality of intermediate pairs from a first plurality C, a second plurality D and a third plurality E where C = V j f fault free , I j fault free I SC system I SC fault − free D = V j fault free V OC system V OC fault free , I j fault free E = V j fault free V OC system V OC fault free , I j fault free I SC system I SC fault free where V OC represents the open circuit voltage and I SC the short-circuit current of the system, - establishing, according to the determined plurality, the set of indicators based on a deviation between the pluralities D and B and/or between the pluralities C and B and/or between the pluralities E and A. <EOS>