Key takeaways:
Xinrui An from JTPV showed that module power gains beyond 650 W come from combining multiple cell-level improvements rather than a single change
Multi-cut cell designs reduce resistive losses, but require effective edge treatment to avoid power losses from recombination
Technologies such as stencil printing and cut line treatment (CLT) contribute incremental efficiency and power gains
It is well understood that both cell- and module-level improvements contribute to the overall power output of a PV module. In a presentation at TaiyangNews’ High-Efficiency Solar Technologies 2025 Conference, Xinrui An from Jietai Solar (JTPV) focused on developments at cell lines that can push the module power beyond 650 W.
He briefly explained JTPV’s previous generation cells MoNo1 that integrate features including stack wafer deposition, optimized emitter contacts, gradient-index anti-reflection coatings, and fine metallization. These cells reached average efficiencies of about 25.5% and a Voc of 740 mV.
The current-generation MoNo2 builds on this by introducing a wave back surface field (WBSF), which adds about 0.15% to the efficiency and 6% to bifaciality. Additionally, half-cut edge passivation (Jietai’s HEP) contributes a maximum of 0.35% efficiency gain with a 5-8 W increase in module power. Several other minor improvements add another 0.1%-0.15% gain in efficiency. At the module level, this translates to about 15 W, reaching 645 W with MoNo2 cells.
An also shared outdoor test results from Yinchuan, China, comparing modules made with MoNo2 against another supplier under identical BOM conditions. After about a year of operation, JTPV’s modules showed about 0.4%-1.8% higher generation. More importantly, the degradation results showed a significant difference, with 0.3%-0.4% for JTPV’s modules versus 2% for the comparison string, after 10 months from installation.
An then moved to the roadmap towards achieving over 650 W modules. The approach is not based on a single breakthrough but a combination of multiple improvements on the cell side, including advanced metallization, multi-cut cell design, and cut line technology (CLT).
On the metallization side, An highlighted steel stencil printing as a promising alternative to conventional screen printing with the main advantage being the ability to produce narrower, taller fingers with a uniform cross-section. Based on experiments, he says stencil printing can increase efficiency by about 0.07% absolute. He also discussed silver-coated copper as a cost-effective alternative for rear-side metallization. By partially replacing silver, it is possible to maintain the efficiency while lowering material costs. However, he stated some challenges, especially with the alignment of busbars with fingers during double printing and current limitations in paste cost reduction.
Another major topic was multi-cut cells, which help reduce resistive losses in ribbons and improve module power. An emphasized that the main advantages of multi-cut cells are the ability to use 213 x 182 mm wafers and the use of negative cell spacing during stringing. Splitting full cells into halves yields a 10-15 W increase in power, but going further to quarter-cut cells only adds about 3-4 W more. At this point, losses at the cut edges become significant, which limits the benefit of further cutting. This is where edge treatment becomes critical, he says.
This is the point where CLT comes into the picture. Instead of leaving the laser-cut edges untreated, CLT removes the emitter along the cut lines and passivates the exposed surface to reduce recombination at edges. An presented results that showed that CLT can recover losses and even provide an additional gain of about 3 W for half-cut and up to 8 W for quarter-cut modules. However, he also specified that without proper edge treatment, multi-cut designs can actually lose power due to increased recombination. This is also evident from experimental results comparing modules with quarter-cut cells with and without CLT and HEP, in which the untreated cells clearly underperform. Combining CLT with edge passivation yields the best results, especially when the current mismatch between the cut-cells is minimized. Finally, An emphasized that additional sorting based on current is necessary; otherwise, 2-4 W of potential power can be lost due to the mismatch. Access his full presentation at Advancing n-Type Module Power.