Photovoltaic modules. Bypass diode. Thermal runaway test (IEC 2979:2017)

2017 ◽  
Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2416 ◽  
Author(s):  
Woo Shin ◽  
Suk Ko ◽  
Hyung Song ◽  
Young Ju ◽  
Hye Hwang ◽  
...  

Bypass diodes have been widely utilized in crystalline silicon (c-Si) photovoltaic (PV) modules to maximize the output of a PV module array under partially shaded conditions. A Schottky diode is used as the bypass diode in c-Si PV modules due to its low operating voltage. In this work, we systematically investigated the origin of bypass diode faults in c-Si PV modules operated outdoors. The temperature of the inner junction box where the bypass diode is installed increases as the ambient temperature increases. Its temperature rises to over 70 °C on sunny days in summer. As the temperature of the junction box increases from 25 to 70 °C, the leakage current increases up to 35 times under a reverse voltage of 15 V. As a result of the high leakage current of the bypass diode at high temperature, melt down of the junction barrier between the metal and semiconductor has been observed in damaged diodes collected from abnormally functioning PV modules. Thus, it is believed that the constant leakage current applied to the junction caused the melting of the junction, thereby resulting in a failure of both the bypass diode and the c-Si PV module.


Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2472 ◽  
Author(s):  
Romênia G. Vieira ◽  
Fábio M. U. de Araújo ◽  
Mahmoud Dhimish ◽  
Maria I. S. Guerra

Solar photovoltaic (PV) energy has shown significant expansion on the installed capacity over the last years. Most of its power systems are installed on rooftops, integrated into buildings. Considering the fast development of PV plants, it has becoming even more critical to understand the performance and reliability of such systems. One of the most common problems faced in PV plants occurs when solar cells receive non-uniform irradiance or partially shaded. The consequences of shading generally are prevented by bypass diodes. A significant number of studies and technical reports have been published as of today, based on extensive experience from research and field feedbacks. However, such material has not been cataloged or analyzed from a perspective of the technological evolution of bypass diodes devices. This paper presents a comprehensive review and highlights recent advances, ongoing research, and prospects, as reported in the literature, on bypass diode application on photovoltaic modules. First, it outlines the shading effect and hotspot problem on PV modules. Following, it explains bypass diodes’ working principle, as well as discusses how such devices can impact power output and PV modules’ reliability. Then, it gives a thorough review of recently published research, as well as the state of the art in the field. In conclusion, it makes a discussion on the overview and challenges to bypass diode as a mitigation technique.


2021 ◽  
Vol 70 (12) ◽  
pp. 1870-1878
Author(s):  
Jaehwan Ko ◽  
Chungil Kim ◽  
Chung-Geun Lee ◽  
Deukgwang Lee ◽  
Myeong-Geun Ko ◽  
...  

Energy ◽  
2017 ◽  
Vol 128 ◽  
pp. 232-243 ◽  
Author(s):  
Suk Whan Ko ◽  
Young Chul Ju ◽  
Hye Mi Hwang ◽  
Jung Hun So ◽  
Young-Seok Jung ◽  
...  

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