Grid-Induced Operational Availability of a Small-Scale Grid-Connected Photovoltaic Power Plant: Diagnostic Methodology and Results of Annual Monitoring in Uzbekistan

Abstract This study proposes and validates a differentiated methodology for assessing the grid-induced operational availability of a small-scale grid-connected photovoltaic power plant operating in a low-voltage distribution network in Uzbekistan. The case study is a PV plant installed in the Khatyrchi district of the Navoi region, equipped with a 10-kW grid-connected inverter and a 10.7 kWp photovoltaic array. Based on a full-year monitoring dataset for the leap year 2024, this study analyzed the annual energy generation, protective trip logs, voltage parameters, and structure of generation interruption events. The system generated 13894.7 kWh of electricity, corresponding to 1389.5 kWh/(kW·year) when normalized to the inverter rated power and 1298.6 kWh/(kWp·yr) when normalized to the PV-array peak power. The results indicate no evidence of significant underperformance of the photovoltaic subsystem. The 613 recorded events with a total duration of 306.5 h are interpreted not as proven equipment failures but as protective trips or generation interruptions caused by external grid conditions and inverter protection logic. Calendar availability was 96.51%, whereas availability within the 2900-h potential solar-generation window was 89.43%. Overvoltage in the low-voltage network was the dominant unavailability factor, accounting for 433 events or 70.6% of all interruptions. Scenario analysis shows that reducing overvoltage-related trips by 50–75% could increase solar window availability to 93.16–95.03%. The practical contribution of this study is an operational energy audit algorithm that separates grid-induced unavailability from equipment-related failures and supports technically justified measures to reduce generation losses.

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