Markovian reliability analysis of standalone photovoltaic systems incorporating repairs

This paper presents an improved method to accurately determine the reliability and optimum size of standalone photovoltaic (PV) systems. The loss of load probability (LOLP) is used as a criterion. Markovian models are used to simulate the stochastic behavior of the system and to assess a more realistic value of LOLP taking the failure and repair rates of each component into consideration. The methodology is demonstrated by determining the optimum size, for a given LOLP, of a standalone PV system. The introduction of failure-and repair-induced unavailability of the system's components resulted in a larger LOLP (by 25%), over that calculated without consideration of the failures and repairs. Thus, the proposed method allows the realistic quantification of the system's reliability that can lead to the accurate prediction of the lifetime energy yield and the levelized cost of energy.