Solar energy is the cheapest and most accessible form of energy. With continuous research and practical application, the efficiency of panels will improve year by year. Two years ago, we announced a breakthrough in the Netherlands and China, achieving an unprecedented efficiency of approximately 27%. What has happened since then?
Scientists at a Chinese solar technology company will develop a new type of solar cell in early 2023 that is said to be a game-changer in the world’s transition to renewable energy. The advanced modeling carried out by Delft University of Technology researchers played a pivotal role in understanding and engineering the innovation. The new solar cell was made of the same material as 95% of all solar cells today, but it was much more efficient at 26.81%. This innovation further strengthens the important role of solar cells in the energy transition. The research results were published in the journal Nature Energy.
energy barrier
The key to the enhancement in 2023 was the “nanocrystalline silicon hole contact layer,” which has excellent electrical conduction. The development involved leading companies such as LONGi Green Energy Technology Co., Sun Yat-sen University and Delft University of Technology. Although this advance surpassed previous crystalline silicon cell architectures, future production applications remained untested. Insights from detailed modeling by Delft University of Technology reveal the energy barriers within these cells, pushing the limits of conventional expectations. With research published in Nature Energy, this innovation has the potential to have far-reaching impacts, in line with global efforts to accelerate the adoption of renewable energy. So the question is, what has happened since then?

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new research results
First, a disclaimer. Considering the huge amount of research in knowledge institutions, large companies and start-ups, it is impossible to give a complete overview. Conclusion: Over the past two years, solar cell efficiency has made significant progress, surpassing the 26.81% efficiency achieved in 2023. Notably, in December 2024, Qcells, a subsidiary of Hanwha Corporation, set a world record by achieving 28.6%. Efficiency of large-area silicon solar cells featuring a perovskite top layer.
This tandem approach leverages the excellent light absorption properties of perovskite materials in combination with traditional silicon to increase overall efficiency. Also, although not a record, this month (January 2025), Chinese solar power company Trina Solar achieved an efficiency of 25.44% in an n-type fully passivated heterojunction (HJT) solar module. did.
HJT technology improves efficiency by effectively covering surface defects in solar cells, thereby improving performance. Additionally, also in January 2025, JinkoSolar announced that its perovskite silicon tandem solar cells have an efficiency of 33.84%. The “trick” here is, of course, the combination with perovskites. This achievement highlights the potential of combining perovskite and silicon technologies to overcome traditional efficiency limits.

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solar energy conversion
These developments represent a promising trend toward increasing the efficiency of solar energy conversion, bringing us closer to more cost- and space-efficient photovoltaic solutions. Let’s go back to pure silicon. The best experimental cell, with an efficiency of 27.4%, approaches the 29.4% figure that is almost universally considered the limit of silicon cell performance. A research paper published in January 2025 claims that “the assumptions used to estimate this limit are too restrictive because they do not incorporate solar directionality.” The researchers show how this directionality and the angular response of the cell can be co-existently quantified by projecting both angular dependencies onto the solar module plane. “Even a simple scheme that takes advantage of directionality, such as installing solar modules facing the equator with a near-latitudinal tilt, increases the theoretical limiting efficiency by more than 29.4%. These cells are designed for solar tracking systems, including axial trackers, and such cells have a theoretical efficiency limit of over 30%.”