Hotspot testing of glass/backsheet and glass/glass PV modules pre-stressed in extended thermal cycling

Journal Article · Mon Dec 12 00:00:00 EST 2022 · Solar Energy

DOI:https://doi.org/10.1016/j.solener.2022.12.006· OSTI ID:2007054

Afridi, Muhammad ^[1]; Kumar, Akash ^[1]; ibne Mahmood, Farrukh ^[1]; Tamizhmani, Govindasamy ^[1]

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1. Arizona State University, Mesa, AZ (United States)

This paper investigates the effect of hotspot (HS) stress endurance of two of the latest designs of monocrystalline modules: a half-cell glass/backsheet (G/B) module and a full-cell glass/glass (G/G) module. These modules have already been pre-stressed in extended thermal cycling with 600 cycles per the IEC 61215 standard to represent field-stressed modules. This study differs from the other conventional studies wherein only fresh modules are subjected to hotspot endurance stress. The G/G module reached a maximum temperature of approximately 200 °C at a cell shading of 25 %, 55 °C higher than the maximum hotspot temperature of 145 °C in the G/B module. A significant burn mark, without glass shattering, was observed in the hotspot-stressed cell of the G/G module due to the current mismatch induced by partial shading. Most of the cells in the G/G module appear to be severely damaged (severe dark areas), as observed in the electroluminescence (EL) image, while the dark regions were rarely present in the G/B module. The EL image also illustrates multiple cell cracks that resist current flow and eventually contribute to the full-cell module degradation. About 8.3 % degradation in maximum power was observed for the G/G module and 1.3 % for the G/B module after the sequential stress tests. The lower degradation in the G/B module can potentially be attributed to its design, which comprises of two parallel strings, each having 72-half-cells and benefits from lower heat dissipation. Furthermore, this indicates that the half-cell design could potentially minimize the hotspot degradation and failures in crystalline-silicon modules.

• Research Organization: Arizona State University, Mesa, AZ (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0008565
• OSTI ID: 2007054
• Journal Information: Solar Energy, Vol. 249; ISSN 0038-092X
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
Accelerated life test (ALT)
Half-cut cell
Glass/backsheet
Glass/glass
Thermal cycling
Hotspot