Technologies are described herein for synchronizing multiple direct current (“DC”) voltages provided by multiple power sources. Multiple input voltages are received from multiple power sources. A voltage control signal indicating a desired output voltage is issued to multiple DC-DC converter modules electrically coupled to the multiple power sources. A master DC-DC converter module from the multiple DC-DC converter modules converts a master input voltage to a master output voltage that is substantially equal to the desired output voltage. The master output voltage is then provided to the remaining multiple DC-DC converter modules. Each of the remaining multiple DC-DC converter modules then converts a slave input voltage to a slave output voltage that is substantially equal to the master output voltage.