BE20 pilot reported electrical system malfunction after takeoff resulting in a return to the departure airport.

Narrative

Arrived at ZZZ to pick up the Beechcraft B200GT; to ferry it for a friend. After some maintenance work and checking all the systems; everything was working perfectly. I departed and after the gear was selected up it sounded labored. The gear systems sounded struggling to get up. The breaker popped; the generator 1 and 2 dropped and the avionics panels went black. My clearance by ZZZ Tower was climb to 2;000 ft and contact Departure. Because the panels went black; I lost communication 1 and 2 and also I lost my transponder to set 7600 to show loss of communication. I decided to maintain 2;000 ft to stay inside the ZZZ airspace and went back to the downwind leg for Rwy XX. I looked at the tower on the downwind for the light gun signal flashing green; but I could not see it; I decided to land before the standby altitude and airspeed indicator ran out of battery. On final I believe I saw the steady green light from tower. After I landed the aircraft and taxied back to the hangar the mechanics checked the hydraulic system and gear and no faults noted. The next day I checked all the electrical system again and after calling the mechanic I decided to not fly as the day before that; my flight plan was from ZZZ to ZZZ1. I made a short flight as a test flight to ZZZ2 with a handheld radio and a portable GPS just in case of a communication failure again. The flight was perfect. Then I flew from ZZZ2 all the way to ZZZ3 and delivered the aircraft all perfect to my friend.