By George Touloupas

This article was originally published in pv magazine – August 2024 edition. Learn more about the pv magazine test here.

George Touloupas, senior director of technology and quality at Clean Energy Associates, analyzes the August 2024 results from the pv magazine test outdoor installation in Xi’an, China. 

View previous PV Magazine Test Results

A recently installed product from Runergy now offers its first full month of available data. Due to system downtime, three days of data have been excluded. We will also start removing old samples to make room for new products. The Risen PERC product, #32, has now been removed from the test field.

The first chart below shows the meteo station data (irradiance and ambient temperature) for August 2024.

The average bifacial boost was 8.97% for August 2024. Bifacial boost is defined as the relative advantage of the average specific energy yield of all bifacial products compared to the average specific energy yield of all monofacial passivated emitter rear contact (PERC) products. The chart below shows the relative specific energy yield comparison between different PV module technology.

The newly installed tunnel oxide passivated contact (TOPCon) products performed well in their first month. However, some n-type products that started at the top rank have fallen to lower ranks after only a few months of operation, while others seem more stable. Longer observation time is needed to draw conclusions on the causes of this behavior.

TOPCon continues to have a higher bifacial boost than heterojunction (HJT), but more HJT products are needed to be studied over time to draw conclusions. 

Energy yield measurements

• The energy yield comparison among various technologies, including bifacial boost, is 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 into categories, per solar module type.

• The bifacial boost depends on a number of parameters: the bifaciality factor, the installation geometry, the albedo of the ground, the sun angle, and diffuse irradiance. The ground in this case is gray gravel.

Test cooperation

pv magazine test is a cooperative effort involving pv magazine, CEA, Gsolar and Hoymiles. 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.