JA Solar has concluded one year of tests to compare its n-type and p-type bifacial PERC solar modules at a testing field located at China’s National Center of Supervision and Inspection on Solar Photovoltaic Product Quality (CPVT) in Yinchuan, in the Ningxia Hui region.
The company conducted the tests between February 2021 and February 2022. The results were confirmed by Germany’s TÜV Nord. The testing location has an annual average temperature of 8 C and an annual average solar radiation of 2,800 to 3,000 hours with a solar spectrum very close to the standard illumination conditions (AM1.5).
The testing field comprised a 6 kW unit equipped with n-type panels and a 6 kW unit relying on p-type products, with an inverter of 20 kW being connected to both sets. The panels were installed on fixed structures with a tilt angle of 40 degrees and at a height of 1 meter above the ground.
The company measured the performance of the array via an environmental monitoring system, a double-sided irradiance meter, a high-precision DC meter, and a temperature sensor. It exclusively used data from the DC meter for the assessment.
JA Solar found that the daily average energy yield of the n-type and p-type panels was 5.03 kWh/kW and 4.84 kWh/kW, respectively, which means n-type modules had a 3.9% higher energy yield compared to their counterparts.
“While both types of modules are based on half-cut bifacial solar cells, the energy yield difference is mainly due to cell technology performance,” said the manufacturer.
The company said the n-type modules operated at an average temperature that was 1 C lower than that of the p-type panels, by virtue of their lower temperature coefficient of -0.3% per degree Celsius, which compares to -0.35% per degree Celsius for the p-type products.
“The n-type module has 80% bifaciality which is much higher than the 70% of PERC modules,” the company said. “Assuming irradiance under the rear side is 100 W/m2 to 150 W/m2 condition, the 10% bifaciality difference can bring n-type module energy gain 1%~1.5%, when the albedo is 20%~30%. The PVsyst simulation shows 0.8%~1.2% more power generation can be seen due to this factor.”
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