Novel Research Reveals: Decreasing Solar Modules per String Minimizes Hotspot Risks

A team of researchers hailing from the University of Surabaya in Indonesia has delved into a comprehensive study concerning the early - stage operational glitches of a 24.9 MW solar photovoltaic (PV) power plant situated on Sumatra Island in western Indonesia.

The research commenced in August 2022, coinciding with the plant's commissioning, and reached its conclusion in August 2024.

Elieser Tarigan, the principal author, elucidated, "The relatively brief operational span ensures that the detected defects mainly originate from factors prevalent in the early operational phase, rather than from long - term wear and tear. Our research is centered around classifying and quantifying the diverse types of defects we've observed, such as hotspot effects, glass fractures, junction box malfunctions, and glass that has become foggy or discolored, with the aim of understanding how these impact the system's performance."

In total, the Sumatra - based solar installation encompasses 64,140 PV panels, each boasting a capacity of 390 W. All these panels are installed in a ground - mounted setup, where the modules are linked in series to form strings. Each string consists of 30 modules connected in a sequential manner.

The researcher elaborated, "During the on - site observations, we closely monitored the operating voltage and current and compared them with the technical specifications of the modules to unearth any potential irregularities. Our focus was on pinpointing anomalies in the power output of specific module strings. A string was flagged as abnormal when the power output shown by the inverter was markedly lower than the theoretical values calculated for that string under the prevailing environmental conditions. These anomalies were then further probed to determine if there were any defects in the modules."

Subsequently, the investigation of individual modules involved visual inspections accompanied by direct measurements. The more in - depth analysis incorporated detailed measurements and thermal imaging techniques. The data amassed from the visual inspections and measurements was meticulously analyzed to ascertain the prevalence and the extent of impact of each defect type.

The scientists expounded, "The observational results demonstrate that within the initial two - year operational period, out of a total of 64,400 installed PV modules, around 678 modules manifested operational irregularities triggered by the various defects we previously mentioned. The observed failure rate, approximately 1.05%, underscores the critical importance of early - stage monitoring and maintenance in safeguarding the reliability and long - term viability of PV systems."

Based on the findings, the majority of the issues were associated with hotspot formation. Specifically, 350 junction box failures were detected, 282 cases of glass cracking occurred, 42 instances of junction box swelling were noted, and seven cases of glass turning foggy or discolored were identified. Moreover, instances of shading caused by surrounding objects like trees, poles, and buildings, as well as self - shading among PV arrays, were also recognized.

Professor Tarigan summarized, "Our analysis has revealed that half - cut modules outperform full - cell modules in alleviating hotspot effects. This is attributed to their lower current per cell and enhanced bypass diode configuration, which lead to reduced heat dissipation and power losses. Additionally, reducing the number of modules in a string effectively brings down the string voltage and current, thereby minimizing the severity of hotspots."