Particle Swarm Optimization (PSO) technique has been applied for multi-junction solar cell system. The solar panels are made up of different materials and give constant output from Boost converter. The main aim of PSO is to find out duty cycle to the Boost converter to maintain constant output voltage irrespective of power produced by solar panels. A detailed simulation of the proposed method has been simulated in Matlab/Simulink. The simulation result shows that this design can be effectively realized in practical applications. © 2016 IEEE.