Question

A solar Photovoltaic (PV) system consists of a PV panel, a charger controller, a battery, and an inverter. The manufacturer of the PV system guarantees 20 years of lifetime of the entire PV system with reliability of 0.90 at the end of 20 years. The failure rate of its major components is given in Table 1. To achieve the overall system reliability goal, we can add redundant units for each subsystem (see Figure 2). Note that System A is the original design, and System B is the new design with the addition of redundant components. Your objective is to determine the number of redundant units for each subsystem, i.e. ni, n2 and ng such that the system reliability of 0.9 is achieved at the end of 20 years. We assume the PV system only operates 12 hours a day, and lifetime of these components is exponentially distributed (note that the reliability of the PV panel is assumed to be 1 across 20 years, hence it is not listed in table 1 and there is No need of adding redundant units).

Answer 1