PV system reliability and durability investigations are essential for industrial maturity and economic success. Recently, PV systems get a big interest in Iraq due to many reasons for instance, power shortage, global warming, pollution, etc., Solar PV is promising in Iraq, assuming the PV module's efficiency equal to 16%, each 10 km² has the potential to produce estimated energy of about 3.4 billion kWh/year, equivalent to a total capacity of 5.9 GW. The primary objective of this work is to measure the energy and the performance indices of an existing PV plant and identify the most common shortcomings, failure modes and their economic impact on the energy yield and LCoE. To improve the grade of the future outlook of PV plants by strengthening the long-term viability of PV and BoS to be implemented in harsh climates. Through delivering lifetime energy based on FMEEA by pointing out all the related failure modes in harsh climates like those of Iraq. 850 kWp, government-asset, flat roof, grid-connected PV plant installed over 6000m² in Iraq/Baghdad-Ministry of Electricity facility was inspected, which is denoted as BWh hot arid with rare to very little precipitation. Data measured and calculated factors revealed a degradation rate of the PV system above the recommended industry values with poor system performance reaching 84% power losses, additionally with an augmentation in O&M costs was noticed after only 36 months of operation.