Lower Levelized Cost of Energy Achievement of Silicon Heterojunction Solar Modules with Low Water Vapor Transmission Rate Encapsulants

The damp‐heat (DH) degradation of silicon heterojunction (SHJ) solar modules leads to severe power loss, necessitating superior‐quality encapsulation materials. Herein, it is aimed to investigate the mechanical, thermal, and optical properties of ethylene vinyl acetate (EVA), polyolefin elastomer (POE), and thermoplastic polyolefin (TPO). TPO demonstrates the lowest water vapor transmission rate (WVTR) of only 3.14 g (m 2 ·day) −1 , which is approximately seven times lower than that of EVA. The Fourier transform infrared spectroscopy of EVA demonstrates a loss of the carbonyl group, revealing the formation of acetic acid under DH stress, which is not observed in POE and TPO. Both glass/back sheet and glass/glass (G/G) modules show a significant influence of encapsulant material on DH degradation. The maximum output power ( P max ) of the G/TPO/G single‐cell module maintains 96.6% of its initial value after 1000 h DH stress. After sealing the edge, the G/G commercial‐size modules encapsulated with lower WVTR encapsulants display excellent DH reliability, and P max degrades <4.8% after 3000 h of DH stress. The predicted levelized cost of energy (LCOE) decreases ≈0.11 US cents/(KW h), which boosts additional power generation and illustrates the remarkable potential for the SHJ solar modules meeting the requirements of reliable, sustainable, and low‐LCOE systems.