Prototype of a low-cost AC-side anomaly detection and alert system for residential photovoltaic installations

The increasing deployment of residential photovoltaic (PV) systems calls for affordable and reliable monitoring solutions to enhance safety and operational awareness. This paper presents a prototype Indicator Light Photovoltaic (ILPV) system for low-cost AC-side anomaly detection and alerting in small-scale PV installations. The system integrates a voltage sensor (ZMPT101B) and a current sensor (ACS712) with an ESP32 microcontroller to provide real-time measurements, visual status indicators, audible alarms, and optional Wi-Fi–enabled remote notifications. Experimental validation was performed under two supply scenarios, grid and standalone inverter, using both no-load and 10 W load tests. Results showed voltage measurement accuracy within 1% of a calibrated multimeter, detection of load-induced voltage drops, and current variations averaging 0.035 A under load. The system also detected transient overvoltage events, registering a simulated surge of approximately 6 V in milliseconds. While testing was limited to low-power indoor conditions and AC-side monitoring, the ILPV demonstrated the ability to classify basic supply states and promptly alert operators. Designed as a scalable, cost-effective add-on, the ILPV can serve as a secondary protection and awareness layer in residential PV systems, with future work extending capabilities to PV-side fault detection, environmental sensing, and outdoor real-world deployment.