Data collected from a 30 MW PV project in Tianjin Province, China show that n-type tunnel oxide passivated contact modules (TOPCon) produce just over 5% more energy than p-type PERC. Analysis by JinkoSolar, which supplied its TOPCon modules to the project, credits the improved performance of the n-type modules to a better temperature coefficient in the project’s hot climate, higher bifaciality and lower degradation.
The investigated 30 MW project was developed by CGC in Jixian, Tianjin Province. The project has 20MW consisting of two different 545W p-type PERC modules from unnamed manufacturers, with the rest being 555W n-type TOPCon modules supplied by JinkoSolar. All modules are mounted on a fixed tilting shelf at a 30 degree angle and are connected in series of 26 modules with one 225kW inverter for every 17 strips.
The performance of the two module types was analyzed during the first two weeks of February 2023. During this period, n-type modules were shown to produce an average of 169.53 kWh per installed kW, an increase of 5.02% from 161.43 kWh. kW is achieved on the construction site with the best-performing p-type module.
N-type advantage
Module manufacturer JinkoSolar, which supplied the n-type modules for this project, says this data illustrates TOPCon’s reported advantages over PERC in action. The manufacturer cites the higher efficiency and better bifaciality of the n-type modules as the main reasons for the improved performance. Better bifaciality (about 70% for PERC and 80% for TOPCon) could explain the 1-1.5% yield increase.
The data collected during the coldest part of the year in Tianjin province is only two weeks, so it is more difficult to draw other benefits directly from this case study. However, JinkoSolar also cited a lower decay rate for its n-type modules – 1% in the first year and 0.4% per year thereafter, which most likely adds about 1.8% yield to PERC’s typical 2% decay in the first year. 0.45% per year.
Finally, it cited the lower temperature coefficient of n-type modules – 0.29% performance loss per C temperature rise compared to 0.35% for PERC modules – as the reason for the 2% additional yield, noting that this advantage would be more apparent in the project studied during the summer months when the temperature can reach 30 C and higher.
