Protecting Heterojunction Solar Modules with UV-Downshifting, UV-Blocking

Why It Matters

UV degradation erodes power output and lifetime of high‑efficiency HJT panels, so the new encapsulation strategy can boost energy yield and reduce replacement costs for large‑scale PV installations.

Key Takeaways

• Dual-layer encapsulant preserves >98% performance after 120 kWh/m² UV exposure.
• UV-downshifting layer converts UV to blue light, boosting initial efficiency.
• Adding UV-blocking layer stops unconverted UV, reducing degradation.
• Dual-layer modules outperform UV-transmitting encapsulant by 8.92% post‑aging.
• Lightweight HJT cells benefit from combined downshifting and blocking strategy.

Pulse Analysis

Heterojunction (HJT) solar cells have become a benchmark for efficiency, yet their lightweight designs are vulnerable to ultraviolet‑induced degradation (UVID). UV photons can break down encapsulant polymers and impair cell performance, especially in bifacial modules that expose both sides to sunlight. Industry analysts have long sought materials that either block harmful UV or convert it into usable wavelengths, but most solutions sacrifice either durability or initial power output. Understanding this trade‑off is crucial as developers aim to maximize energy yield over a 25‑year project horizon.

In a recent study, a German team tested four encapsulant configurations on 156.75 mm HJT cells, including standard UV‑transmitting EVA, two UV‑blocking polyolefins, and an EVA formulation loaded with downshifting particles. After accelerating exposure to 120 kWh/m²—equivalent to roughly 30 months of German outdoor conditions—the dual‑layer design (UV‑downshifting EVA atop a UV‑blocking layer) retained over 98% of its baseline efficiency. Compared with a purely UV‑transmitting module, the dual‑layer system achieved an 8.92% higher post‑aging efficiency, primarily because the downshifting layer redirected UV photons into blue light that the HJT cell can harvest, while the blocking layer captured any residual UV that escaped conversion.

The implications extend beyond academic interest. By mitigating UVID, manufacturers can offer lighter, higher‑output modules without compromising long‑term reliability, a key factor for utility‑scale farms and building‑integrated photovoltaics where weight and space are premium. The approach also aligns with sustainability goals, as fewer module replacements translate to lower embodied carbon. As the PV market pushes toward 30‑plus‑percent efficiencies, integrating UV‑downshifting and blocking encapsulants could become a standard design element, prompting supply‑chain adjustments and new certification criteria. Future work will likely focus on scaling the particle‑laden EVA layer and quantifying cost‑benefit ratios for commercial deployment.