Evolutionary process development towards next generation crystalline silicon solar cells : a semiconductor process toolbox application

Abstract

Bulk crystalline Silicon solar cells are covering more than 85% of the world's roof top module installation in 2010. With a growth rate of over 30% in the last 10 years this technology remains the working horse of solar cell industry. The full Aluminum back-side field (Al BSF) technology has been developed in the 90's and provides a production learning curve on module price of constant 20% in average. The main reason for the decrease of module prices with increasing production capacity is due to the effect of up scaling industrial production. For further decreasing of the price per wattpeak silicon consumption has to be reduced and efficiency has to be improved. In this paper we describe a successive efficiency improving process development starting from the existing full Al BSF cell concept. We propose an evolutionary development includes all parts of the solar cell process: optical enhancement (texturing, polishing, antireflection coating), junction formation and contacting. Novel processes are benchmarked on industrial like baseline flows using high-efficiency cell concepts like i-PERC (Passivated Emitter and Rear Cell). While the full Al BSF crystalline silicon solar cell technology provides efficiencies of up to 18% (on cz-Si) in production, we are achieving up to 19.4% conversion efficiency for industrial fabricated, large area solar cells with copper based front side metallization and local Al BSF applying the semiconductor toolbox.

Oxide passivated low reflection nano-structured solar cell

“…John et al have reported that anti-reflection coating produced with the silane free precursor from Sixtron Applied Materials in solar cell production. Using it in the rear side passivation stack on top of SiO x , best cell results in local Al BSF solar cells have been measured around ~ 18% [19].…”

Cell interconnection without glueing or soldering for crystalline Si photovoltaic modules

“…Despite their relative maturity, solar cells and photovoltaic modules based on mono-or polycrystalline silicon still have potential for improvement, in terms of higher conversion efficiency as well as in terms of cheaper manufacturing [1]. Here we present experimental results on an interconnection method of solar cells, which permits higher power output per module area and may also lower production costs.…”

Investigation of Silicon Saw Damage Removal and Surface Texturing Using KOH for next Generation Silicon Solar Cells

“…The need for cheaper levelized cost of PV-originated electricity (LCOE) and to finally reach grid parity translates in a need for cheaper solar cells with an increase in conversion efficiency [1]. In order to reach this goal novel cell concepts and novel fabrication methods have to be developed for implementation in industrial process lines [2]. In this context wet processes should also evolve towards easy to implement, well controlled and cost effective steps [3,4].…”