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The first topical lecture of the day was presented by Prof. dr. Christoph J. Brabec from FAU Erlangen-Nürnberg, who talked about material discovery for emerging PV technologies. ‘The silicon PV that is the leading technology of today is nearing its fundamental limit when it comes to efficiency. We believe the future of solar cells is in multijunction cells, that combine different materials.’ To identify interesting candidate materials that can improve the efficiency of solar cells, his group has experimented with automated methods. ‘Taking into account aspects like toxicity and cost of goods, the artificial intelligence based system managed to identify a number of promising candidate molecules. These proved to be indeed better performing than state of the art materials, not only in our own lab, but also in other groups working with different cell architectures. I think automated methods like these can truly transform the way we do this type of research.’

After lunch, Andrew J. Bissell from Sunamp Ltd and Prof. dr. Colin R. Pulham  from University of Edinburgh gave a sparkling duo presentation on how they came together to jointly develop a thermal energy storage solution, of which by now over 40,000 copies have been built. Bissell: ‘At Sumamp, we wanted to develop a heat battery that would combine a high energy density with a high energy efficiency and high power, for fast charging and de-charging. We were looking at sodium acetate trihydrate, a phase changing material that should be able to do the trick, but encountered problems with its performance. Via an organization in the UK called Interface, we were linked to Colin.’ Pulham: ‘Though the initial assignment was rather boring, I took it, because I needed to keep a member of staff on board for about a month. But during my first talks with Andrew, I discovered there was a quite interesting underlying problem in understanding and controlling the crystallization process.’ The collaboration has since won multiple prizes, and ha resulted in success for both partners. ‘The science has enabled us to go to market years early,’ Bissell stated. ‘Since we knew what the outcome of cycle testing would be, we started selling our heat batteries long before the test results came in. And the scientists were right: our system tends to fail mechanically before breaking down chemically, leading to lifetimes resembling or even exceeding those of conventional water boilers.’

The final speaker of the day introduced the human factor in the energy system. Prof. dr. Kirsten Gram-Hanssen from Aalborg University stated that users are different from what designers and engineers tend to think. ‘For example, our studies have shown that people living in old, badly isolated houses, tend to consume less energy than could be expected, while people living in new, well-isolated homes typically use more energy than needed. Economic factors do not explain this fully: even the richest people living in old houses are more energy efficient than their peers living in new homes. And the poorest people in new homes still consume more energy than we would expect. Energy consumption is not intentional, it is the result of what we are doing on a day. So, if we want to make the energy transition a success, we do not need to think about changing behavior, but instead we need to change practices if we want people to consume less energy, and in a more flexible way.’