A microgrid (MG) is a secondary (low voltage) network capable of supplying part or all the power needed by the connected users. It is composed by solar panels, energy storage devices, diesel plants, microturbines, and all other distributed generation technologies available for connecting to the low voltage grid. In this paper, a MG model is presented to minimize operation cost during a 24-hour period. Decisions of the MG are taken by a Virtual Power Player (VPP) which manages available resources, such as solar panels, energy storage devices (ES) and Demand Response (DR). The resulting mathematical model is a linear programming problem, which is solved using a commercial software. The results show that adequate management of available resources lead to economic operation of the MG and modifies the load behaviour.