22.5 percent efficient Si solar cells lower costs via kerfless wafers
Claiming an industry first, imec and Crystal Solar have demonstrated the highest efficiency to-date for homojunction solar cells on epitaxially grown silicon wafers, paving the way toward industrialization of this promising technology. The efficiency was certified by FhG ISE CalLab.
Crystal Solar’s manufacturing technology called Direct Gas to Wafer enables direct conversion of feedstock gas to mono crystalline silicon wafers by high throughput epitaxial growth. By skipping the polysilicon, ingoting and the wire-sawing steps altogether, the approach not only results in lowest cost/watt for the wafers but also reduces the capital required to set up a manufacturing plant. The process also enables the growth of high quality p-n junctions in-situ which reduces cell making steps while increasing the efficiency.
Imec has adapted the research center’s efficient nPERT Si solar cell process to align with the properties of Crystal Solar’s kerfless wafers. The 156×156 mm2 cells were fabricated on 160 to 180 um thick grown n-type wafers with built-in rear p+ emitter. Imec’s n-PERT process included a selective front surface field realized by laser doping, advanced emitter surface passivation by Al2O3 and Ni/Cu plated contacts. The novel process using all industrially available processing steps resulted in record efficiencies for homojunction large area solar cells of 22.5 percent and a record Voc of 700 mV. The high Voc illustrates the high quality of the wafers and the built-in junction.
Jozef Szlufcik, PV Department Director at imec, said: “The combination of our advanced cell process and the innovative wafer manufacturing technique of Crystal Solar, is paving the way for manufacturing of highly efficient solar cells at substantially lower cost and will be disruptive for the complete solar manufacturing value chain.”
T.S. Ravi, CEO of Crystal Solar, commented: “This approach represents a new paradigm in cell manufacturing with its unique ability to bypass significant steps in both wafer and cell manufacturing thereby dramatically reducing the capex and the overall cost per watt. We expect to achieve >23% efficiencies with imec’s PERT technology in the very near future”.
Related articles and links:
News articles:
Imec extracts 22% efficiency from crystalline silicon n-PERT solar cells
Next-generation silicon solar cells: Imec extends collaboration with Total
Reducing data centre energy consumption on three levels
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
