A sub-sea power supply includes a plurality of transformers, a wet-mateable connector, and a plurality of passive rectifier circuits. Each transformer includes a primary coil and secondary coil. The primary coils are coupled in parallel. The wet-mateable connector is coupleable to a sub-sea AC power source. The wet-mateable connector is coupled to the primary coils. The plurality of passive rectifier circuits is respectively coupled to the secondary coils. The plurality of passive rectifier circuits is configured to generate substantially uniform polarity voltage outputs coupled in series.