Perovskite-silicon tandem solar cells: 35.5% record efficiency in 2026

In July 2026, LONGi, a Chinese company and one of the world’s largest manufacturers of photovoltaic modules, set a new absolute record for perovskite-silicon tandem solar cells, achieving a certified efficiency of 35.5% under laboratory conditions. This result is more than just a figure on a technical datasheet: it concretely marks the overcoming of the physical limits of pure silicon and opens a new phase for global photovoltaics.

What are tandem cells and why they change the rules of the game

Conventional solar cells are based on a single layer of crystalline silicon, a material that, despite decades of optimization, faces a physical limit in converting sunlight into electricity. The reason is structural: each semiconductor material absorbs only a specific portion of the light spectrum. However, sunlight is composed of vastly different wavelengths—from ultraviolet to infrared—and a single semiconductor cannot efficiently capture all of them.

Perovskite-silicon tandem cells elegantly solve this problem by stacking two layers of semiconductor material with complementary properties. Perovskite—a synthetic material with a unique crystal structure—preferentially absorbs higher-energy wavelengths (blue and green light), while crystalline silicon captures lower-energy wavelengths, extending into the red and infrared. The result is a much broader spectral coverage and, consequently, a higher conversion efficiency than can be achieved with any single material.

This dual-layer architecture enables surpassing the theoretical limits of traditional silicon-based photovoltaics, a boundary that for years has represented the upper limit of the conventional solar industry.

The 35.5% record: how it was certified

The 35.5% efficiency figure is not a self-declared claim by LONGi: it has been validated by ESTI, the European reference institute for the certification of photovoltaic technologies. Certification by an independent third-party body is fundamental in this sector, because laboratory results must be reproducible and measured according to standardized protocols to be recognized by the international scientific and industrial community.

The record was officially confirmed in July 2026 and represents the highest level ever achieved for this category of solar cells. For a concrete point of comparison: crystalline silicon photovoltaic modules currently available on the commercial market typically operate between 20% and 23% efficiency. Reaching 35.5% in the laboratory means that the gap between frontier technology and commercial products is still wide, but also that the potential for improvement is real and measurable.

LONGi published the details of the result on its official European website, with technical documentation supporting the ESTI certification.

The challenges that still separate the laboratory from the market

A record laboratory efficiency is a major scientific milestone, but it does not automatically translate into solar panels available on a home roof within a few months. Perovskite-silicon tandem cells must still overcome two main obstacles before they can compete on a large scale with traditional modules: durability and production costs.

On the durability front, perovskite has historically shown greater sensitivity to humidity, prolonged heat, and photodegradation compared to crystalline silicon, which in commercial modules typically provides yield warranties exceeding 25 years. Achieving durability standards comparable to those of crystalline silicon remains one of the main active research areas worldwide.

On the economic front, the production of tandem cells requires more complex deposition processes than single-junction cells, with unit costs still significantly higher. Industrial scalability—meaning the ability to produce these cells in large volumes while maintaining consistent quality—is a technical challenge that has not yet been resolved at the commercial level.

This does not mean that LONGi's result is far from practical application; it means that the path from a record-breaking cell to an installable module still requires process engineering, accelerated aging tests, and significant industrial investment.

Why this record matters for the future of solar energy

Photovoltaics is already one of the fastest-growing energy sources in the world, but its competitiveness largely depends on the amount of energy that can be generated per square meter of installed capacity. Each additional percentage point in efficiency means less surface area is required to produce the same amount of electricity — a significant advantage in urban settings, on roofs with limited space, or in installations where land costs are a major factor.

A commercial module that one day approaches the efficiencies currently achievable only in the laboratory with perovskite-silicon tandem solar cells could substantially reshape the cost-benefit ratio of solar energy. The 35.5% efficiency certified by ESTI is not a final destination: it is an indicator of where this technology can go, and the fact that it was achieved in 2026 by a company with industrial-scale production capacity such as LONGi makes it particularly significant.

The road to commercialization is still long and riddled with technical problems to be solved, but each new record pushes forward the boundary of what is physically possible — and accelerates the work of those in laboratories and factories around the world who are trying to bring that possibility into real life.

This article was produced with the support of AI and subjected to editorial review.