The role of photovoltaic cells in our energy transition
There has been a heightened sense of urgency to the conversation on energy in recent years. With 75 per cent of the world’s current energy consumption coming from non-renewable sources such as fossil fuels, oil, and nuclear energy, the plan to switch to an inexhaustible and clean resource is constantly on the table.
The world’s demand for energy has increased over the last century by a staggering 100,000 billion Kilowatthours, a unit of energy used to measure domestic energy consumption. This figure is expected to double by 2100 – the same as having 66,666 billion air-conditioners on at the same time.
By then, our dependence on fossil and nuclear fuels can hopefully be replaced by regenerative energies such as solar energy. But do we have the technology to harness enough solar power to satisfy the world’s needs?
Professor Detlef Bahnemann, Head of the Photocatalysis and Nanotechnology Research Unit at the Institute for Technical Chemistry, Leibniz University, Director of the Laboratory for Photoactive Nano-composite Materials at St. Petersburg State University, and Distinguished Professor at Shaanxi University, delivered the first Sir John Monash Lecture for 2021 on “The Role of Photovoltaic Cells in our Energy Transition”, which he states is a key element to realising the possibility of using solar power alone to supply enough energy for the world’s use. He began his lecture with an overview of traditional solar cells, saying that “we are very near to the maximum possible efficiency” for silicon solar cells, which is about 27 per cent He also discussed thin-film cells and how, although they are highly effective, the materials required for production are precious and extremely costly.
Increased efficiency of the current solar technology will pave the way for it to become a main source of energy. Professor Bahnemann illustrated several ways in which cell efficiency could be increased but mentioned that we should “take into account that some of these processes are very complex.” Among the processes that were explained included tandem-cells and concentrator-cells, which are generally produced for specific applications such as for use in space.
The direction that future research on photovoltaics will take is ultimately to address the current technological deficiencies and the issues of cost and process complexity. Professor Bahnemann’s focus, however, was on the newly emerging technology of organic Dye Sensitised Solar Cells or DSSCs, raising the amusing, but thought-provoking question: can laptops run on spinach? DSSCs are not only low-cost and easier to produce than silicon cells, but they can outperform silicon cells in terms of efficiency.
The highlight of the lecture was the discussion of third-generation solar cells and the material perovskite, which according to Professor Bahnemann “has potential for efficiency that goes above and beyond all other materials, which places perovskite in a very interesting role in the future of photovoltaics”.
He revealed that we are currently at the breaking point of cracking this technology, and ended his lecture on an optimistic note, saying that “there is still much to do, but I’m confident that in a few years, we will have solar cells that are easy to make, non-toxic, and inexpensive.”