Novel Utility-Scale Photovoltaic Plant Electroluminescence Maintenance Technique by Means of Bidirectional Power Inverter Controller

Abstract

Nowadays, photovoltaic (PV) silicon plants dominate the growth in renewable energies generation. Utility-scale photovoltaic plants (USPVPs) have increased exponentially in size and power in the last decade and, therefore, it is crucial to develop optimum maintenance techniques. One of the most promising maintenance techniques is the study of electroluminescence (EL) images as a complement of infrared thermography (IRT) analysis. However, its high cost has prevented its use regularly up to date. This paper proposes a maintenance methodology to perform on-site EL inspections as efficiently as possible. First, current USPVP characteristics and the requirements to apply EL on them are studied. Next, an increase over the automation level by means of adding automatic elements in the current PV plant design is studied. The new elements and their configuration are explained, and a control strategy for applying this technique on large photovoltaic plants is developed. With the aim of getting on-site EL images on a real plant, a PV inverter has been developed to validate the proposed methodology on a small-scale solar plant. Both the electrical parameters measured during the tests and the images taken have been analysed. Finally, the implementation cost of the solution has been calculated and optimised. The results conclude the technical viability to perform on-site EL inspections on PV plants without the need to measure and analyse the panel defects out of the PV installation.

Infrared Thermography for the Detection and Characterization of Photovoltaic Defects: Comparison between Illumination and Dark Conditions

“…In this case, the module is forward biased with a power supply, to achieve a current similar to the Isc of the module. Other working points, as 10% of Isc, are commonly selected to better distinguish certain types of failures [11,19].…”

“…A specific power inverter with bidirectional power flow capability was placed in the pilot-site for this study. The power inverter is a NPC I-type that has been recently developed to help in the maintenance of PV plants by means of EL image processing [19]. Indeed, the three-level neutral point clamped (NPC) configuration is one of the most extended topologies in PV inverters currently on the market.…”

“…However, PV inverters are not usually prepared to start under low-irradiance conditions, and some minor hardware modifications are required in this sense [19]. A DC-link pre-charge system is required to perform inspections in low-irradiance environments.…”

“…Concluding the inspection systems, electroluminescence (EL) imaging is another technique for failure identification in PV modules in which defective areas are darker, because disconnected parts do not irradiate [ 18 ]. Although it is one of the most promising maintenance techniques, its high cost has prevented its use regularly up to date [ 19 ]. It is a well-established non-destructive technology that can be used in the manufacturing process of the modules, transported to a lab after unmounting the PV modules from the site or on site, with an assembly or a specific tripod or also by means of EL cameras mounted on UAVs.…”

A Secondary Reconfigurable Inverter and Its Control Strategy

“…With the development of power electronics technology, voltage source inverters have been widely used [1][2][3][4]. The power semiconductor devices of the inverter and its control circuit constitute the weakest link, which is vulnerable to being faulty.…”