KPIT STEM Dialogues

Dr. Martin Green: Pioneering Solar Energy for a Sustainable Future | KPIT STEM Dialogues

Q: Dr. Martin Green, you've had a career spanning over 50 years in the solar energy field. Could you start by telling us what first sparked your interest in science and technology?

My journey into science began in high school, where I was deeply influenced by a talented physics teacher and the experiments we did, such as observing electrical signals on an oscilloscope. Mathematics and physics were always my strongest subjects, and my early experiences in studying electrical circuits steered me toward electrical engineering. The rapid developments in microelectronics at the time further solidified my interest and guided me toward a career in semiconductor electronics and later into solar energy.

Q: What led you to focus on solar photovoltaic (PV) technology, and how has it evolved over the years?

My work in semiconductor electronics eventually intersected with solar energy when I began researching how to improve the efficiency of solar cells. In the 1970s, solar cells were primarily used in spacecraft because they were expensive, but the 1970s oil crisis spurred interest in alternative energy sources. Over time, the focus shifted to making solar cells cheaper and more accessible for widespread use on Earth. Today, solar PV technology has become the most affordable source of electricity, and my team’s contributions, such as the development of the PERC (Passivated Emitter and Rear Cell) structure, have helped drive this progress.

Q: One of your significant contributions was improving the efficiency of solar cells. Could you explain some of the key breakthroughs your team achieved?

The efficiency of solar cells is a measure of how much sunlight is converted into usable electricity. When I started my research, the efficiency of solar cells was around 16.5%. Through continuous innovation, such as the tunneling structures and PERC technology, we incrementally improved the voltage and power output of cells. Over the years, we set 13 or 14 successive world records in silicon cell efficiency, eventually achieving a record of 40.6% efficiency in converting sunlight to electricity. Each incremental improvement was significant, and this process took over 25 years of dedicated research.

Q: What role did your students play in the growth of the solar industry, particularly in China?

I had six PhD students from China in the 1980s and 90s, and many of them became pioneers in China’s solar manufacturing industry. One of my students set up the first commercial solar cell production line in China in 2002, at a time when the country lacked the necessary infrastructure. He, along with others, built companies that have since become global leaders in solar manufacturing. Their work was crucial in lowering the cost of solar cells, and China’s dominance in the industry today can be partly attributed to their efforts.

Q: How have the costs of solar cells changed, and what has driven this dramatic reduction?

The cost of solar modules has dropped by 99.8% over the last 50 years, which is a staggering achievement. This has been driven by technological advancements like PERC and Topcon (Tunnel Oxide Passivated Contact) structures, which improved efficiency, as well as economies of scale as the industry grew. The competition within the industry has also played a major role in driving down costs. Today, solar power is cheaper than electricity generated from fossil fuels like coal and natural gas.

Q: Looking forward, what do you see as the future of solar energy, and how do you envision it transforming global energy use?

I believe we are at the beginning of an energy revolution, driven by the affordability and scalability of solar power. Solar energy has the potential to provide 100 times more energy than what the world currently uses from fossil fuels. I foresee a future where solar and wind power dominate, coupled with energy storage solutions like batteries. This will allow us to move away from dirty fossil fuels and towards a sustainable, renewable energy future. In countries like Australia, we are already seeing solar rapidly displacing coal, and I expect this trend to accelerate globally.

Q: You mentioned earlier the importance of both continuous hard work and conceptual breakthroughs in achieving success. Could you share some examples of these “aha” moments in your research?

One of the key conceptual breakthroughs was the idea of using small-area contacts in solar cells, which we developed in the 1980s. This method improved efficiency by reducing resistance and enhancing the directional movement of electrons. Another significant moment was the discovery that we could heat the devices to higher temperatures than previously thought, which led to further efficiency gains. These kinds of insights, combined with persistent incremental improvements, have been crucial in advancing the field.

Q: For young scientists and engineers entering the field today, what advice would you offer?

My advice would be to remain intellectually curious and persistent. Solar energy is a rapidly evolving field with many exciting opportunities. Start small, tackle manageable problems, and build from there. Additionally, communication skills are vital — being able to convey complex ideas effectively can make all the difference in research and innovation. We’re on the verge of massive changes in the energy landscape, and there are endless possibilities for young researchers to make a significant impact.

KPIT STEM Dialogues | Dr. Martin Green discusses the factors that shaped his career