The information below was originally published (in English) on the PV Tech website. Reproduction in Brazil authorized by JA Solar.
To study and verify the power generation performance and operating temperature of different types of modules, JA Solar and TÜV NORD carried out a one-year power yield test (February 2021 to February 2022) in an experimental power plant located in Yinchuan, China.
Now that the semi-annual data are available, the relevant data from this study are presented below.
project information
The project is located in Yinchuan, where there is a temperate continental climate with an arid environment, with an average annual peak hours of 1650 kWh/m2 (horizontal level), an average annual sunlight duration of 2800 to 3000 hours, and an average temperature annual temperature of 8,5 ℃. Yinchuan is one of the regions in China with the highest solar irradiation and a solar spectrum very close to the AM1.5 standard. The test design is shown in Figure 1.
The pilot plant is equipped with a set of monofacial modules DeepBlue 3.0 (182 mm silicon wafer) and a set of single-facial high current modules (Isc > 18 A), with an installed power of approximately 7 kW (measured by the field test laboratory) for each set and a 20 kW inverter for both sets (consisting of bidirectional MPPT input, one direction for each set, with maximum input current of 25 A).
A fixed support structure with a fixed inclination angle of 40° is adopted for installation, about 1 meter above the ground.
In addition to the environmental monitoring system, the project is equipped with an irradiance meter, a high-precision direct current meter and a temperature sensor.
To eliminate the effect of inverters on the power generation performance of different modules, only DC meter data is used for the analysis.
Power generation performance comparison
The energy yield performance of JA Solar 182 modules and high current modules between February 2021 and August 2021 is shown in Figure 2.
The average daily energy yield of these two module types is 4,88 kWh/kW and 4,79 kWh/kW respectively, with the 182mm modules outperforming the high-current modules by about 1,9%.
We can also see that when the irradiation intensity increases (sunny weather, especially from May to July), the energy yield of 182mm modules is 2,5% higher or more than those with high current.
The power generation capacity of photovoltaic modules varies with the power degradation temperature coefficient, working temperature and power generation performance at a low irradiance level.
Although both types of modules are based on half-cell P-type mono-PERC solar cells, each of them has a different operating current according to the difference in wafer sizes.
The high current module employs a 12BB design, while the 182mm JA Solar module uses an optimized 11BB design.
Theoretically, since the internal resistance loss of 182mm modules is relatively smaller, the differences in power generation performance of the two module types are caused by the difference in internal resistance loss and its resulting difference in operating temperature.
In order to check and analyze the module operating temperature differences caused by different operating currents, we extract the operating temperature data and corresponding radiation intensity of the two module types in sunny and high-irradiance climates.
According to the data shown in Figure 3, it is clear that the average operating temperature of the 182mm module is 1,7℃ lower than that of the high-current module, with the maximum temperature difference being 4℃ to 5 ℃.
When the radiation intensity decreases, both the operating current and the temperature of the modules are reduced accordingly, resulting in a smaller difference in the operating temperature of modules with different current levels.
Therefore, the difference in operating temperature mainly derives from the radiation intensity. This demonstrates that the advantage of the 182 m modules in power generation from May to July is due to the increase in the operating temperature difference between the two types of modules.
According to theoretical analysis, excessive operating current of a module will cause a significant increase in heat loss at the metal contact surface of the cell, solder zone and busbar, and the increase in heat loss will lead to an increase in temperature operating temperature, which was also verified by previous analyzes based on operating temperature data from full and half modules.
