The field test, conducted by TÜV Nord at a field testing base in Kagoshima, Japan, was conducted from October to December 2024 as part of a year-long study.
It found that JinkSolar’s TOPCon modules generated an average of 8.82% more energy per watt than n-type BC modules developed by an unnamed manufacturer, with the highest monthly gain reaching 9.84%.
The test setup consisted of two modules from each manufacturer installed on fixed mounts 1.2 meters from the ground at a 32-degree tilt angle. The initial power of the modules was measured using the SAT method, with spectral correction not considered in the test results.
The study collected energy yield (DC) data with a sampling interval of one minute, alongside module plane irradiance, backsheet temperature, ambient temperature, humidity and atmospheric pressure, also all at one-minute intervals.
The normalized energy yield of JinkoSolar’s TOPCon modules reached 294.2 kWh/kW over the three months, compared to 270.2 kWh/kW for the n-type BC modules.
Analysis of energy yield performance under different irradiance levels found that for most of the testing period, irradiance levels were below 1000 W/m². Under these conditions, the average energy yield gain of n-type TOPCon modules reached 8.05%.
JinkoSolar added that Kagoshima’s rainy season was “an ideal setting to showcase the superior low-light performance of TOPCon modules.” Its modules achieving an average daily energy gain of 9.13% per watt during a continuous 15-day stretch of rain from Oct. 15 to Oct. 29.
Under higher irradiance conditions (above 1,000 W/m²) the total three-month energy yield of TOPCon modules was 174.04 kWh, with a yield gain per watt of 8.10% compared to n-type BC modules.
“This indicates that TOPCon modules can deliver higher yield under both low-irradiance rainy weather and high-irradiance sunny weather, thanks to their excellent low-light performance and high bifaciality coefficient,” said JinkoSolar.
The study also measured the performance ratio (PR) of each module by comparing actual energy yield with the theoretical yield based on rated power and specific weather conditions. It calculated the PR value of TOPCon modules at 97.8%, compared to 89.9% for the n-type BC modules.
JinkoSolar said this demonstrates “that bifacial TOPCon modules with high bifaciality offer significant advantages in energy yield efficiency for ground-mounted power stations.”
