Energetica India Magazine: september 2020

58 energetica INDIA- September_2020 SOLAR POWER spections, as well as verification of all the activities in the plant. This maintenance is carried out in regular intervals decided by the OEM and O&M planning commit- tee and are included in the annual main- tenance plan. An example of preventive maintenance is thermographic inspection which aims to identify defective panels on a PV plant. Several defects like hotspots, moisture ingress, soiling, etc can occur on the module, significantly reducing the productivity of the modules. Therefore, relevant inspection procedures are per- formed either by hand-held cameras or by using drone technology. 2. Corrective maintenance : It corre- sponds to any activity performed to restore a PV plant system, equipment, or component to an earlier functioning state. This occurs after fault detection by remote monitoring or during an on-site inspection. These activities includes • Fault diagnosis - to identify cause of fault and locating it. • Temporary repair - to restore the re- quired function of a faulty item for a lim- ited time, until a permanent repair is car- ried out. • Permanent repair - to resolve the fault permanently. 3. Predictive maintenance : This is a condition-based maintenance carried out due to the results from analysis and evaluation of the significant parameters of the degradation of an item. The opera- tions team does predictive maintenance through regular monitoring, supervision, forecast, and performance data analysis. Data Analysis for Predictive maintenance Since predictive analysis is forecasting derived activity, there is a constant need for data analysis to ensure the well-being of the plant. The different types of data analysis done on the plant are: • Breakdown analysis: This analysis can help identify any specific problem of different components. Breakdowns can be divided in 2 types - Forced breakdown and Scheduled breakdown. Forced breakdown/unwanted break- down can occur because of poor device quality, poor installation quality, inade- quate maintenance, loose termination, voltage surges due to lightning, etc., while scheduled breakdown occurs during any planned maintenance. • Historical Generation and Perfor- mance Analysis: This analysis helps in forecasting the future performance of the power plant. This includes monthly, quarterly, annual as well as year-on-year analysis. It also included analysis of dif- ferent losses in the plant e.g. AC losses, Auxiliary losses, Plant unavailability, In - verter efficiency losses, etc, which also detailed further in Loss Analysis • Inverter Efficiency Analysis: Inverter efficiency is a very important parameter which is often not monitored. It is simply the ratio of Inverter’s output by input, but there are two ways to calculate it: power efficiency and energy efficiency. Power efficiency is the instantaneous efficiency of the inverter and various parameters like %loading, operating temperature, etc. The efficiency profile (%efficiency vs