This paper presents the design of a fuzzy controller for maximum power point tracking of an isolated photovoltaic system. The error between the measured voltage and that at maximum power point of the photovoltaic panel is used as single input for the controller. A simulation model was implemented in Matlab/Simulink and consists of a buck converter, a H bridge inverter with LCL filter, the proposed fuzzy controller, and a 300 W load at 120 VRMS and 60 Hz. The performance of the proposed system was compared with one using the Perturb and Observe (P&O) algorithm in the control stage. For both systems the performance was measured in terms of power generated and settling time and it is observed a superior performance with the fuzzy controller, with a decrease in the response time of 95%, and an increase in the extracted power of 2.61%.