Currently, the direct conversion of solar energy into electricity is being accepted as an important form of power generation. This electricity generated by a process known as the photovoltaic effect, using photovoltaic (PV) system. The operating power of PV system depends on the sun's intensity, the ambient temperature and the PV system output voltage (PV load). The maximum power point tracking (MPPT) algorithms usually are used in PV system in order to make the system operate with maximum efficiency. Many of MPPT algorithms/techniques for PV system have been proposed vary in complexity, sensors required, convergence speed and dynamic response, cost, range of effectiveness, implementation hardware, popularity, and in other respects. In this paper, some most widely-used of MPPT algorithm will be reviewed and studied, in order to develop a PV model with MPPT algorithm, refer to an existing a small scale gridconnected PV array system at Szent István University (SIU). Simulation results of MPPT line characteristics, both for ASE-100 (polycrystalline technology) and DS-40 (amorphous silicon technology) modules, as main components of grid-connected PV array at Szent István University, will be shown, as a preliminary step to understand the voltage critical values of each module at different weather conditions.