This project aimed to improve solar cell performance and reduce production costs by mass-producing solar cells using large-scale commercial manufacturing. It achieved the world’s first 20% efficient p-type CZ cell fabricated using commercial equipment, 10 years ahead of the timing predicted by international experts.
The efficiency of commercial solar cells (the amount of energy converted from sunlight) has increased significantly in recent years while their costs have fallen by more than 50%. Yet most commercial solar cells perform well below leading laboratory technologies such as the Passivated Emitter Rear Locally diffused (PERL) solar cell from the University of NSW, which has a record efficiency of 25%.
This project investigated ways to improve solar cell performance and reduce production costs by mass-producing solar cells using large-scale commercial manufacturing.
This involved the identification of ways to incorporate the high efficiency aspects of laboratory solar cell designs into low cost versions of the designs that are suitable for mass production at greatly reduced costs.
Report: Overcoming the Fundamental Performance Limitations of Commercial Solar Cells
This report details new areas of solar cell technology that when used in conjunction with each other would overcome the fundamental limitations of conventional solar cell technology for standard p-type commercial grade silicon wafers.
UNSW in collaboration with industry partner Suntech R&D Australia has further developed the selective emitter technology and applied similar principles and high efficiency attributes to the rear surface design of the devices.
New performance records have been achieved for standard CZ wafers although perhaps more importantly the new technology is compatible with low cost multicrystalline silicon wafers. The development of an advanced and patented hydrogen passivation technology has enabled such material to be transformed into being of similar quality to the much more expensive monocrystalline silicon wafers. This is expected to eventually lead to the achievement of efficiencies above 20% following the already successful pilot production efficiency of 19% and corresponding module efficiency in excess of 18% at the end of this project.
Of key importance is overcoming the degrading effect of prolonged high temperatures on low-cost wafers, which has been achieved via innovative approaches for localised formation of heavily doped regions and subsequent self-aligned metal application to these heavily doped regions. This means the remainder of the wafer is not subjected to high temperatures and avoids the associated problems.
The success of this approach has led to world record efficiencies for solar modules comprising solar cells made from this type of multicrystalline silicon.
To achieve the highest possible efficiencies, this project addressed the remaining major source of cell performance limitation recombination of photo-generated current carriers at the rear surface. Working with its industry partners in this project, UNSW investigated the advantages of low cost, light induced plating (LIP) metallisation. Subsequent stages of the project looked to eliminate rear surface recombination by investigating a variety of surface passivation and localised metal contacting schemes, building on the PERL (Passivated Emitter Rear Locally diffused) cell structure developed by UNSW over many years of research.
In addition, the program investigated possible increased efficiencies in the PERL solar cell, potentially opening up new avenues for cost effective industrial manufacturing.
The project brought together the ultimate performance-enhancing attributes of UNSW’s PERL solar cell structure in a simple and cost effective industrial sequence to drive down solar cell costs and increase performance to levels where electricity generated from sunlight can compete on an equal footing with any conventional electricity source in almost all the residential markets of the world.
The work has been particularly successful in leading towards this, with photovoltaics now cost competitive with fossil fuel-generated electricity at retail level in most major countries.
Ongoing development of the Pluto technology has taken place throughout the project, which has led to numerous world records for commercial cell efficiencies using p-type wafers for both mono and multi wafers; including Suntech breaking the 15-year old world record for multi modules of 15.5%, previously held by Sandia National Laboratories in the USA.
In addition to the various innovative and patented features of the Pluto cell that have contributed to the record performance levels, the improved rear surface design allowed a new world record of 19.7% efficiency to be achieved in early 2011, followed later the same year with 20.3% efficiency, almost 10 years ahead of the timing predicted by international experts.
In parallel with developing the Pluto technology for p-type CZ wafers, the technology was developed and adapted to also suit multicrystalline silicon wafers as part of this project. This was seen internationally as a major breakthrough in moving towards high performance low cost commercial wafers due to this being the first time that high performance cell technology had ever been able to be successfully applied to the low cost wafers that have significant thermal constraints compared to counterpart mono wafers.
- UK Energy Institute International Technology Award (2010-11) for the importance and success of the Pluto technology
- MIT Technology Review (USA), listed Suntech as one of the world’s Top 50 Technology Companies internationally in 2011
- Fast Company named Suntech as one of China’s Top 10 most innovative companies in 2011.
- Australian Collaborative Innovation Award (2012) for the innovativeness and success of the technology development between UNSW and Suntech.
- PV Tech awarded Suntech’s high efficiency photovoltaic module as the most innovative product of 2011
- A F Harvey Engineering Prize (2013/14), awarded by the UK Institution of Engineering and Technology and widely regarded as one of the top international prizes in all fields of engineering
ARENA awarded funding of $2,970,702 to the University of New South Wales in Round 1 of the Research and Development Program conducted in 2014 to continue to develop a number of key technology innovations critical to the development of the next generation of commercial high performance silicon solar cells.
Project profile: Towards ultimate performance silicon solar cells