A protection system configured to protect plural DC voltage sources configured to be connected in parallel between first and second input terminals of a voltage inverter. The voltage inverter can convert a DC input voltage into an AC output voltage. Each DC voltage source is connected by a first electrical conductor to the first input terminal and by a second electrical conductor to the second input terminal. The protection system includes: for each DC voltage source, a first cut-off member and first detector of a defect of isolation of the first conductor with respect to an electrical ground, the first detector and associated first cut-off member connected in series between the corresponding DC voltage source and the first input terminal of the inverter; and a mechanism triggering, in event of detection of the isolation defect, the associated first cut-off member to open the electrical link corresponding to the first conductor.