Australian solar pioneer receives European innovation prize

Scientia Professor Martin Green from the University of New South Wales, Sydney, has received the 2022 Millennium Technology Prize for his innovation that transformed the production of solar energy. The €1 million award for technology, conferred every two years, recognised Green’s leadership in the development of the Passivated Emitter and Rear Cell (PERC). Since its development in 1983, the PERC has reportedly become one of the most commercially viable and efficient silicon solar cell technologies for use in solar panels and for large-scale electricity production.

Green developed the PERC by improving the quality of both the top and rear surface of standard silicon solar cells. When sunlight — in the form of particles called photons — enters a cell, it excites the electrons within the silicon. In this excited state, electrons can move through the cell, creating an electric current. The improved surface of the PERC allows the electrons to maintain this excited state — or move freely — for longer, resulting in greater and more efficient energy generation. The PERC has helped increase the conversion efficiency of standard solar cells by over 50% in relative terms from 16.5% in the early 1980s to 25% in the early 2000s.

The innovation has also reduced the costs of using solar panels, making solar energy more affordable than fossil-based alternatives. PERCs can also provide an energy supply to homes without them needing to be connected to a grid, thereby providing a reliable power supply for remote communities. Professor Green said that the prize not only recognised his contribution to photovoltaics (the conversion of light into electrical power), but also the achievements of his students and research colleagues at UNSW, as well as those of the broader photovoltaic research and commercial community.

“I believe the Prize will increase my credibility as a spokesperson for what needs to be done to address climate change. We need to switch from fossil fuels to renewable energy to sustain the trajectory of human civilisation on our shared planet. The pace of change is accelerating and the world will shift to solar and wind energy over the coming decade. I believe a huge transformation of historic significance is underway,” Green said.

Green and his team are working on combined cell technologies to reach 40% solar cell efficiency by exploring options such as stacking cells on top of each other. “Solar cells are increasingly being used to replace large power stations that use fossil fuels. In 2021, 20 countries or regions generated 8% to 25% of their total electricity supply from solar energy, with this number growing quickly. The rapid cost reductions in solar energy that my work has facilitated have come just in time, right at the point when the importance of acting immediately to address climate change has become overwhelmingly obvious,” Green said.

Professor Päivi Törmä, Chair of the International Selection Committee of the Millennium Technology Prize, said: “PERCs can help us provide low-cost energy solutions and mitigate climate change. Continued research on solar cells is needed to replace their constituents that have limited supply, such as silver, with more abundant alternatives.”

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