CGC Sanya Test: TOPCon Bifacial Modules Show Significant Power Gain of 3.6% Over BC Bifacial Modules, with Morning and Evening Increase Reaching 8.92%

As photovoltaic modules are increasingly used in renewable energy systems, the energy yield is the most key parameter that can directly affect the LCOE, so ensuring real-world performance and reliability in different daytime and weather  conditions has become the focus of current research. Herein, the three-month performances of both TOPCon and N-type BC  bifacial modules were monitored, compared, and analyzed in Yazhou District, Sanya City (18.39  ° N, 109.22  ° E ), Hainan province from May 1 to July 31, 2025.

The environmental parameters were investigated for both systems under ambient conditions. Irradiance was determined as the primary influencing parameter in the system.

System design

Each of the 10 modules in Jinkosolar, s TOPCon and N-type BC has an average measured power of 634.15 W and 641.81 W, respectively,

The two solar arrays were installed in the same location to ensure the same ambient conditions, at a height of 2 meter above grass ground with the tilt angle of the module was 15° to the south.

For three months from May  1 to July 31, 2025, the energy yield, irradiance, as well as the module, and ambient temperatures were monitored. Additionally, the electrical parameters for the two modules were compared in the different hours per day and different irradiance conditions during the study period.(shown as Table 2)

Results

The energy yield (kWh/kWp) from the two test group modules cell were compared. The yield of TOPCon bifacial module system was 3.6% higher than that of the N-type bifacial system. The PR values of the TOPCon and N-type BC from the STC were found to be 98.98% and 95.55%, respectively(shown as Figure 2)

Figure 2    Comparison of Power Generation Performance of JinkoSolarTOPCon

Modules and N-Type BC Modules

The energy yield gain varies in different time duration across the day. The highest yield gains occurred in early morning 6am-7am and late afternoon 6pm-7pm, which were  11.25% and 7.62%, respectively (shown as Figure 3)

Figure 3    Comparison of power generation between TOPCon and

BC modules at different time periods

The energy yield gain also differs in different irradiance condition.  The lower the irradiance, the higher the yield gain of TOPCon over N-type BC, the highest of 9.13% at irradiance if 0-100W/m2 (shown as Figure 4).

Figure 4     Comparison of power generation between TOPCon and

BC modules under different irradiance levels

Conclusions

These analysis results revealed that the lower the irradiance the higher the energy yield of TOPCon versus N-type BC to a value higher than that obtained in present study (+3.6%).

The loss mechanism for lower yield of N-type BC was attributed to low bifaciality and poor low irradiance performance due to cell properties (multiple leakage current  effects and grid on the back side) . These analyses also revealed that the TOPCon energy yield gain over N-type BC can be increased further to 11.25% and 7.62%  in early morning 6am-7am and later afternoon 6pm-7pm respectively.The average energy yield gain of TOPCon over N-type BC module is 8.92% in dusk and dawn.  This study can contribute to achieving higher energy yield from PV systems during field applications. This can contribute to the design of products with higher energy yield and lower LCOE in the PV industry.