Résumé: he kWh price of renewable energy power plants is still very costly, so any malfunction or weak yield is prejudicial to guarantee the investment payback. Therefore, in this case, sustainability re-assessment of the whole system is required. In general, faults are difficult to detect, and very quickly they evolve rapidly and exponentially. Keeping the faulty part in operation has a negative influence on the other healthy parts, through additional electrical constraints, which increasingly weaken them (risk of cascading faults). So, it is important to detect faults early in order to eliminate or correct them. Early detection implies in-depth diagnosis, for this purpose, several detection processes require the planned disconnection of photovoltaic power plant production. This technique has negative economic repercussions

Résumé: The reliability of any electrical power system must be evaluated in order to increase durability. In accordance with the IEEE standard 1366, 2012, reliability is modeled by quality of service and profitability indices. This reliability highly depends on the applied grid code. An investigation was conducted on data recorded during these last five years since 2018 from OUED KEBRIT PV power plant located in Algeria. It was highlighted in this paper that the inverter power controller can decrease significantly the reliability. In many cases electrical protections of PV power plant react by disconnecting it, whereas the fault is outside. Data mining shows that many PV power plant breakdowns are not necessary. A modified active and reactive power control strategy was applied to the PV power plant and compared to the existing one