An embedded microcontroller unit for PV module monitoring and fault detection

This paper presents the architectural lay-out and functional design details of a microcontroller embedded electronic monitoring system (e-EMS). According to the design, this unit is integrated into the PV module junction box. It can be scaled up to form part of a complex PV power plant control system. The communication topology follows a 3-tier structure. It uses two processors, one dedicated for data acquisition and the other for communication purposes. The e-EMS provides a complete set of data associated to PV module performance characteristic parameters, including current and voltage of the PV module and each sub-string of cells, operation of the bypass diodes along with the corresponding current and voltage measurements, PV temperature and environmental parameters. The sampling rate can be programmed in a large range from 1 to 65s along with the number of samples used for averaging signal values. The power output is determined every hour, as a basic output of the system. Comparison of the determined values with the expected ones when normalized to the PV operating conditions provides reliable information on deviation trends, the degree of degradation that the PV module experiences, while the analysis of the sampled data may identify the cells or modules which experience degradation and disclose types of factors which affect their operation.