ECN publication
Title:
High efficiency n-type metal wrap through cells and modules
 
Author(s):
Guillevin, N.; Heurtault, B.; Aken, B.B. van; Bennett, I.J.; Jansen, M.J.; Geerligs, L.J.; Berkeveld, L.D.; Weeber, A.W.; Bultman, J.H.; Zhiyan, Hu ; Gaofei, Li ; Wenchao, Zhao; Jianming, Wang; Ziqian, Wang; Yingle, Chen; Yanlong,  Shen; Jianhui, Chen; Bo, Yu; Shuquan, Tian; Jingfeng, Xiong
 
Published by: Publication date:
ECN Solar Energy 1-10-2012
 
ECN report number: Document type:
ECN-M--12-028 Conference Paper
 
Number of pages: Full text:
7 Download PDF  

Presented at: Silicon PV Conference, Leuven, , 3-5 april 2012.

Abstract:
This paper describes results of metal wrap through (MWT) cells produced from n-type Czochralski silicon wafers, and modules produced from those cells. The use of n-type silicon as base material allows for high efficiencies: for front emitter contacted industrial cells, efficiencies upto nearly 20% have been reported. MWT cells allow even higher cell efficiency, and additionally full back-contacting of the MWT cells in a module results in reduced cell to module (CTM) losses. MWT cells were produced by industrial process technologies. The efficiency of the MWT cells reproducibly exceeds the front contact cells based on the same technology by about 0.2-0.3%, and routes for further improvement are analysed. 60-cell modules were produced from both types of cells. The MWT module, based on integrated backfoil, produced 3% higher power output than the comparable tabbed front emitter contact module. In particular differences in CTM loss of current and fill factor will be presented. CTM current differences arise from the higher packing density, and lower reflectance of the backfoil, in MWT modules. CTM FF differences are related to resistive losses in copper circuitry on the backfoil versus tabs. The CTM FF loss of the MWT module was 2.2%abs lower than for the tabbed front emitter contact module. Also here the losses are analysed and routes for improvement discussed.

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