Michael J. Cudzinovic

Process simplifications to the Pegasus solar cell - SunPower's high-efficiency bifacial silicon solar cell

We describe four simplifications made to the fabrication process of our high efficiency bifacial silicon solar cell, the Pegasus, and we examine the effect each of these has on cell performance. There is an increase in external series resistance in going to a single level metallization. There is an increase in short-circuit current by improving the back surface internal reflectance and improving the front surface texture. There is a small loss in efficiency when we increase the cell thickness. Incorporating these changes greatly simplifies the process by eliminating one-third of the major processing step and reduces the fabrication cost by 30%. All of this is done with only a 0.6% absolute decrease in the cell efficiency.

Degradation of surface quality due to anti-reflective coating deposition on silicon solar cells

We find that the front surface quality on back contacted silicon solar cells is degraded by the evaporative deposition of an anti-reflective coating. The degradation is most severe when an e-beam evaporation is performed, but there is still significant degradation with thermal evaporation. The surface recovers some after a forming gas anneal but is still degraded compared to before the evaporation. The degradation overwhelms and negates any forming gas anneal performed prior to the evaporation. The degradation is greatly reduced if the surface is not textured. We discuss the application of these results to our high efficiency silicon solar cells.

18.3% efficient silicon solar cells for space applications

In this paper, the authors report on the development of high-efficiency silicon solar cells designed specifically for space applications. The cells are the 100 /spl mu/m thin N/sup +/-P-P/sup +/ and are 2/spl times/4 cm in size. The front side surface is textured with inverted pyramids and received a double layer anti-reflection coating (ARC). They also have a back surface field (BSF) and a back surface reflector (BSR). Both front and back diffusions are optimized for radiation hardness. The best beginning of life (BOL) efficiencies of these thin (100 /spl mu/m) 2 cm/spl times/4 cm cells have been measured At JPL to be 18.3%. The best end of life (EOL) efficiencies after 1 MeV 1E15 electrons is 12.1%.