The paper presents two contributions; the first is an optimized control structure for Photovoltaic Grid Connected Systems (PVGCS). The power chain is composed of two cascaded power converters, namely, a boost converter and a five-level T-type multilevel converter. Traditionally, each power converter is controlled by a Separate Mode Control (SMC) from the other, which is computationally intensive since each converter requires its own control system, which is not practical. The suggested control, called Integrated Finite Set Model Predictive Control (IFS-MPC), allows controlling cascaded converters at the same time in one stage instead of controlling them separately. Consequently, the overall implementation system is widely reduced. The second contribution of the paper is a modified IFS-MPC called M-IFS-MPC that ensures the correct functioning of the grid-tied PV sys-tem under certain faults in converter components. Indeed, when one of the DC-link capacitors fails or when one of the auxiliary switches breaks down, by selecting an appropriate choice of the DC-link capacitors’ voltage reference, the proposed design al-lows a normal operation without intervention on the power circuit.