A mobile AC-to-DC power conversion system that can convert AC power into DC power for use by facilities that require it, such as telecommunications switching offices, thereby enabling telecommunications services supplied by the facility's equipment to be quickly and easily restored. The system may be arranged to be connected to a source of commercial AC power so that if only the facility's DC generation systems are inoperative, i.e., AC power is available at the site, the needed DC power can be generated from that available AC power source. In addition, however, the AC-to-DC power conversion system may also include an AC generator so that DC power can be supplied to the facility in question when no other source of AC power is available.