Picture_Photovoltaic Hot-Spot

A Fault Detection Method for Solar Photovoltaic Systems to Improve Performance and Lifetime

Prof. Katherine A. Kim co-authored the paper entitled “Photovoltaic Hot-Spot Detection for Solar Panel Substrings Using AC Parameter Characterization,” published in the IEEE Transactions on Power Electronics. Hot spotting in photovoltaic (solar cell) systems in a problem that degrades the panel and decreases output performance. This hot spot detection method uses the inherent characteristics of the photovoltaic cells to determine if a string of cell is experiencing hot spotting or not. The Power Electronics for Advanced Renewable Systems (PEARS) Laboratory at UNIST is continuing this research to fully implement this technique.

 

Title: Detection for Solar Panel Substrings Using AC Parameter Characterization

Authors: Katherine A. Kim, Gab-Su Seo, Bo-Hyung Cho and Philip T. Krein

Abstract: Hot spotting is a problem in photovoltaic (PV) systems that reduces panel power performance and accelerates cell degradation. In present day systems, bypass diodes are used to mitigate hot spotting, but it does not prevent hot spotting or the damage it causes. This paper presents an active hot-spot detection method to detect hot spotting within a series of PV cells, using ac parameter characterization. A PV cell is comprised of series and parallel resistances and parallel capacitance, which are affected by voltage bias, illumination, and temperature. Experimental results have shown that when a PV string is under a maximum power point tracking control, hot spotting in a single cell results in a capacitance increase and dc impedance increase. The capacitance change is detectable by measuring the ac impedance magnitude in the 10-70 kHz frequency range. An impedance value change due to hot spotting can be detected by monitoring one high-frequency measurement in the capacitive region and one low-frequency measurement in the dc impedance region. Alternatively, the dc impedance can also be calculated using dc operating point measurements. The proposed hot-spot detection method can be integrated into a dc-dc power converter that operates at the panel or subpanel level.

 

Journal: IEEE Transactions on Power Electronics (IF: 6.008)

Publication Date: February 2016