In the isolated photovoltaic systems, using battery energy storage, a direct current microgrid may improve the system efficiency, since it simplifies the energy conversion stages. One challenge of this system is the control of the converters, which may be done in a centralized or descentralized manner. In this paper, a descentralized control strategy is proposed, using a voltage droop based on virtual impedance, for a dc microgrid with photovoltaic panels and battery energy storage. For that, the components of the system are mathematically modeled, allowing to design the controllers proposed in this paper. Finally, simulation results obtained with PSCAD/EMTDC software are used to verify the microgrid performance with the designed controllers. With thses results, it is possible to observe the battery charging, as well as variations of the load and of the irradiation on the photovltaic generation.