Today, more than 100 GW of production facilities, the vast majority of PV production in service worldwide, dependent on passivated emitter rear cell technology (PERC). And while it is getting more difficult to find further technological advances, scientists at the German Fraunhofer ISE expect PERC to remain at the forefront of the solar industry for at least the next decade.
ISE modelling indicates a way to achieve 26 per cent efficiency for the technology, marginally higher than commonly thought practical in mass production, and also that PERC cells will function strongly as the bottom cell in the tandem or multi-junction systems that are expected to find their way into mass production in the medium term.
In a comprehensive new article, Passivated Emitter and Rear Cell-Devices, Technology and Simulation, published in Applied Physics Reviews, ISE researchers investigate the 40 years of progress that brought PERC to the prominent role it occupies today, recalling that although the first PERC cell was created in 1989, and related advances date back to the 1970s, the technology’s mass production did not begin.
“An intriguing series of improvements began in 1989 and resulted in a long-standing record of energy conversion efficiency of 25.0 per cent set up in 1999 for the early development of PERCs,” say the scientists. Implementing this structure as an improvement to current manufacturing lines took a decade of intensive technical advancement and another decade to improve the productivity of industrially produced cells to over 22 per cent.’
The ISE researchers measure several changes that they see as a 26 per cent pathway to PERC cell production, without suggesting that this is the only route or the one that the industry can select. These include an extra anti-reflective layer, a significantly thicker 200-micron wafer, and a 30 round wire interconnection without busbars.
“And although the perovskite-silicon tandem cells produced to date have mostly relied on silicon cell heterojunction, ISE notes that PERC is also a strong candidate here: “The industrial PERC system has many features that make serving as a bottom cell very appealing. The bottom unit must be low-cost, and the quantum efficiency and open-circuit voltage of the long-wavelength should be high.
The paper concludes that these variables together mean that PERC technology has a good position to protect and will undoubtedly continue to play a crucial role for years to come in the development of PV. For all other PV technologies to come, comprehensive knowledge of PERC devices, the materials used, efficient machinery, and mature processes, as well as the still accessible capacity, is a good guide,” the scientists conclude.”
Source – here