This paper describes a methodology for implementing in FPGA models of photovoltaic panels for Hardware-in-the-Loop (HIL) and real-time simulations. The proposed methodology integrates numerical solutions, SysML diagrams and Petri nets for structural design and formal validation. In this study, photovoltaic cells have been modeled using the single diode circuit. The photovoltaic panel model is solved by the Newton-Raphson method, and the Lagrange remainder is employed to limit the iteration number. Results show suitable accuracy and performance of the proposed methodology.