pv magazine test: November 2021 Results
By George Touloupas
This article was originally published in pv magazine – January 2022 edition. Learn more about the pv magazine test here.
pv magazine test involves a range of indoor tests, as well as an outdoor performance test in Gsolar’s test facility in Xi’an, China. Some of these tests are standard in the industry, while others are innovative and provide data on important module quality and performance issues.
November 2021 Test Results Explained
Image 1: The mounting structure had to be reconfigured to accommodate large-size modules, without shading of the rear side. M10 (182 mm) products can be seen in this picture.
In the previous issue, we discussed our challenges with high-current modules and the need to both increase the DC cable cross sections and apply corrections to the power values derived from the meters, in order to account for the higher cable losses of high current modules. During November, our partners at Gsola replaced the DC cables with bigger 4 mm² ones, and also modified the microinverters so that the starting time for all product types is the same and we do not have discrepancies from early- or late-day power clipping. In parallel, the CEA team modified the database so that every few minutes a temperature-corrected resistive loss correction would be applied for each PV module, based on the value of its current (I²*R(T) losses).
Image 2: Precision class 0.5 meters, taking current and voltage measurements every five seconds.
Due to the time spent doing these modifications, data collection started on Nov. 20, with an additional three-day gap, due to mandatory power cuts at Gsola’s facility. After a few days of operation, due to the low sun angle at this time of the year, and the fact that the test field underwent an extensive replanning last April, shading was detected on the test field, compromising the energy yield data of these samples. The affected modules were repositioned afterwards, but the November data was already impacted. Fortunately, the section of the field with the bifacial modules was not affected by shading, therefore, in this issue we will present the energy yield results only for the bifacial products. As a result, the bifacial boost will not be listed, as the baseline value of the monofacial module yield is not available.
The chart below shows the meteo station data (irradiance and ambient temperature) for November 2021.
Figure 1: Daily meteo station data - November 2021
Table 1: Average yield values - November 2021
Table 2: Energy Yield Ranking - November 2021
Total Energy Yield
Figure 2: Total Energy Yield - November 2021
Notes on the Energy Yield Measurements
The energy yield comparison among various technologies, including bifacial boost, will be analyzed using products installed after the beginning of 2019.
The energy yield is given in Wh/Wp and calculated by dividing the energy produced by the module by the Pmax at STC of the module. This Pmax is the maximum STC power after a process of stabilization.
The results are grouped in categories, per module type.
The bifacial boost depends on many parameters: the bifaciality factor, the installation geometry, the albedo of the ground, and the sun angle and diffuse irradiance. The ground in this case is gray gravel.
George Touloupas is CEA’s Senior Director, Technology and Quality
Test Cooperation
pv magazine test is a cooperative effort involving pv magazine, APsystems, CEA, and Gsolar. All testing procedures are carried out at Gsolar’s test laboratory in Xi’an, China. CEA supervises these tests and designed both the indoor and outdoor testing procedures.
