Skylane 182/RG Turbo Skylane/RG
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 15
ATC Issue All Types; Aircraft Equipment Problem Critical; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport
Aircraft; Human Factors; Procedure
Aircraft X departed ZZZ IFR initially assigned 040 heading and 4;000 altitude.  Pilot checked on; was identified; handed off and shipped to ZZZ1 Approach having reported established on the airway northbound. Aircraft Y was cleared for the RNAV30 approach at ZZZ and issued direct ZZZ2 (roughly 010) climbing to 4;000 feet on his missed. He was switched to advisory.Aircraft X experienced a total electrical failure.  He lost comms and transponder.  Pilot elected to return to ZZZ VFR.  I was unaware of his intentions and had only a primary only target on his aircraft.  When Aircraft Y checked on; I stopped Aircraft Y at 3;000 feet as Aircraft X's last observed altitude was 4;200 feet with an assigned altitude of 4;000 feet.  Aircraft X descended into ZZZ and the altitude of Aircraft X as they passed about 2 miles lateral from Aircraft Y and whether or not he was VFR was unknown. The operation was as safe as it could be given the circumstances.
A TRACON Controller reported an aircraft experienced a complete electrical failure/communication loss and descended through the altitude of another aircraft while reversing course to return to their departure airport.