Crystalline Silicon Will Drive The Future Of Solar,” Says Dr Radovan Kopecek

The way India has raised the bar in the solar industry shows how innovation and technology have gone hand in hand, especially when it comes to module panels and solar cells. To understand how solar panels have evolved over the years, ResponsibleUs spoke with Dr Radovan Kopecek, Head of Department – Strategy & Education and Member of the Executive Committee, and Co-founder and director of ISC Konstanz, who explained the journey of solar modules from low-efficiency beginnings to today’s highly advanced systems.

Dr Kopecek began by distinguishing solar cells and modules. “The history of solar cells began with very low efficiency; we started with 6% when they were first discovered. Over time, efficiency increased by about 0.5% each year. Twenty years ago, we had solar cells with 15% efficiency, and now we are achieving around 25%,” he said. 

Component quality has also seen major improvement. “The best technology now is double-glass modules, with glass on both sides. Another innovation about five years ago was bifacial modules, which not only absorb sunlight from the front side but also from the rear side. Reflection from the ground makes the panel more powerful,” he added.

According to him, the history of solar panels is complex because it depends not just on the design but also on the materials used inside the module. “For about three years now, solar has been the world’s lowest-cost power source. Efficiency continues to increase while the cost of modules keeps decreasing.”

Solar energy technology has changed over the years. Dr Kopecek said, “The future belongs to crystalline silicon.” While new materials like perovskite are being discussed, he believes that the main technology driving the energy transition will remain crystalline silicon.

“The reason is that crystalline silicon is very powerful and benefits from advances in semiconductor processes. The history of solar cells is based on the evolution of crystalline silicon technology,” he said. He added that while thin-film technologies like cadmium telluride and CIGS had once been hyped, they did not replace crystalline silicon.

On the topic of recycling, Dr Kopecek dismissed the idea that perovskite-based panels are easier to recycle. “It’s not that simple. Many people also say that nuclear fusion is the future, and I would compare perovskite to nuclear fusion in the PV world. It sounds simple because it’s chemistry-based and easy to make, but if something is easy to recycle, it usually isn’t long-lasting. To make modules that last 20, 30, or even 50 years, you need robust technology, like double-glass crystalline silicon,” he said.

Speaking about lifespan, he noted that solar modules today have an energy payback time of just one year in India, and around one and a half years in countries with lower sunlight like Germany. “A module can now last 50 years if made with good materials like polyolefin and stable cells. Cleaning depends on the region—desert regions need regular cleaning, but in countries like Germany, rainfall does the job.”

He also discussed the rapid progress in storage technologies. “Like photovoltaics, storage is evolving quickly and becoming cheaper every year. Over the past two years, battery storage for PV has become so affordable that PV plus storage is now the lowest-cost form of electricity,” he said. His team is also exploring new forms like solid-state storage instead of liquid-based batteries.

“For India, PV and battery storage are already sufficient. In Germany, we also need hydrogen for the winter months. During summer, we convert excess solar energy into hydrogen, which can be used later when sunlight is limited,” he explained.

On the role of rare earth materials in solar manufacturing, he clarified, “For photovoltaics, we don’t rely much on rare materials like germanium. Silicon is abundant, including in India. It may need refinement, but companies are already planning to extract and manufacture silicon ingots and wafers locally.”

“For standard crystalline silicon technologies such as TopCon and TopCon back-contact, rare materials are not a concern. Only in heterojunction technology, indium is needed, which could face a limited supply. But overall, silicon-based photovoltaics remain sustainable and cost-effective,” he said.