A solar cell efficiency record is the highest conversion efficiency an independent laboratory has confirmed for one type of cell. A figure that a research team measures only in its own lab is a claim, not a record.
The records matter because they show how far each technology can go, from the flexible, thin-film designs described in the guide to flexible solar cells to the multi-junction cells at the top of the charts. This page explains what a record is, how it is certified and how to read one.
What counts as a solar cell efficiency record
The best-known register is the “Solar cell efficiency tables” series in the journal Progress in Photovoltaics. According to Version 61 of the tables, the journal has published six-monthly listings of the highest confirmed efficiencies since January 1993. The authors state that the tables encourage researchers to seek independent confirmation of results and to report them on a standardised basis.
The same paper sets the entry rules. The most important criterion is that a result must have been independently measured by a recognised test centre. Efficiencies quoted for the “active area” alone are not included, and the tables allow only three definitions of cell area: total area, aperture area and designated illumination area. Minimum sizes apply as well: above 0.05 cm2 for a concentrator cell, 1 cm2 for a one-sun cell, 200 cm2 for a submodule and 800 cm2 for a module.
These rules explain why a tiny laboratory sample and a full-size module are tracked separately. A record only means something inside its own category.
Standard test conditions: one yardstick for every laboratory
Efficiency depends on the light and the temperature, so laboratories fix both. The PVMET reference on current-voltage measurement explains that the international standard IEC 60904-1 defines idealised conditions to provide comparability between measurements at different laboratories: a device temperature of 25 °C, the AM1.5g reference spectrum and a total irradiance of 1000 W/m2. These settings are known as standard test conditions.
The same reference notes that the current-voltage curve is measured indoors at a solar simulator. Because every certified record is quoted under the same conditions, a figure from one laboratory can be set beside a figure from another.
Who certifies the numbers
Several national and institute laboratories do this work. The pv magazine report on the NREL chart describes the US National Renewable Energy Laboratory’s Best Research-Cell Efficiency Chart as a display of the highest confirmed conversion efficiencies of research cells for a range of PV technologies. The report adds that the cell efficiencies are measured by independent testing centers, including NREL, before earning a spot on the chart, and that all of the figures are available as a downloadable file.
Fraunhofer ISE in Germany runs another well-known facility. In a September 2026 press release, the institute said its calibration laboratory, CalLab, has measured solar cells since 1986 and PV modules since 1991, and has confirmed 152 record results to date. Sixty-six of those records were for modules, mostly silicon, and 86 were for solar cells.
The first CalLab record dates to 1992, when a mini silicon module reached 16.4 percent. The institute’s director said in the same release that impartial and transparently traceable performance measurements enable fair competition, which is the reason independent certification exists at all.
Why single-junction cells hit a ceiling
A cell with one junction has a theoretical limit. The Ossila explanation of the radiative efficiency limit states that the maximum possible efficiency for a single-junction solar cell is 33.7% at an optimum band gap of 1.34 eV. The limit is named after William Shockley and Hans Queisser, who defined it in 1961. It assumes no non-radiative recombination, so real single-junction cells cannot attain it.
Researchers go past this ceiling by stacking subcells made of different materials, each tuned to a slice of the spectrum. The Fraunhofer ISE release notes that research groups worldwide are combining multiple subcells made of different semiconductor materials to exceed the physical limit of silicon. It adds that today’s large-area silicon modules are already close to the physically possible limit, which is why tandem designs now attract most of the attention.
A perovskite-on-silicon tandem passed the single-junction line in 2025. pv magazine reported on 18 April 2025 that Longi had achieved 34.85% for a two-terminal tandem perovskite solar cell, certified by NREL as a world record for that cell type. The previous record, 34.6%, also belonged to Longi, and the new result was described as the first certified efficiency above the 33.7% single-junction limit for a double-junction tandem.
Current records by category
Records are kept per category, so no single number answers the question of the best cell. The table below collects the main figures from the sources used on this page; the Alta Devices result follows in its own section.
| Category | Efficiency | Confirmed by | Year or date |
|---|---|---|---|
| Four-junction cell (III-V), concentrated light | 47.6 percent | Fraunhofer ISE CalLab | 2022 |
| Solar module (AZUR SPACE, temicon, Fraunhofer ISE) | 34.4 percent | Fraunhofer ISE CalLab | Reported September 2026 |
| Two-terminal perovskite-silicon tandem cell (Longi) | 34.85% | NREL | Reported 18 April 2025 |
| Silicon module (Longi) | 26.2 percent | Fraunhofer ISE CalLab | 2025 |
The figures come from the Fraunhofer ISE CalLab anniversary release and the pv magazine report on the Longi tandem cell. Rows reflect the dates shown and may have been overtaken since.
The four-junction entry deserves a note. The Fraunhofer ISE release of 30 May 2022 says the institute raised the best four-junction cell from 46.1 to 47.6 percent at a concentration of 665 suns. The 2026 release states that this quadruple cell, built from GaInP, AlGaAs, GaInAsP and GaInAs, is the world’s most efficient solar cell. That figure applies to concentrated sunlight, so it cannot be compared directly with a flat panel under one sun.
Gallium arsenide and the Alta Devices record history
Gallium arsenide (GaAs) cells have long featured in the record tables. The Fraunhofer ISE release says multi-junction cells made of III-V compound semiconductors have always been among the most efficient solar cells in the world, and GaAs is a III-V material.
Alta Devices, a company based in Sunnyvale, California, built much of its reputation on these records. Semiconductor Today reported on 3 July 2018 that NREL had certified an increase in Alta’s own world record for GaAs single-junction cells from 28.8% to 28.9%, and that the company had set that record five times since 2010. By then Alta had been a subsidiary of Hanergy Thin Film Power Group since 2014. Compound Semiconductor carried the same news on 11 July 2018 and noted that Alta Devices had held continuous world records for solar efficiency for most of the last decade.
One of Alta’s co-founders, Harry Atwater of Caltech, described a 1-sun, 1-junction cell as the archetypal solar cell. The other, Eli Yablonovitch of the University of California, Berkeley, credited the company’s lead to the first solar cell based on internal luminescence extraction.
Applications of high-efficiency III-V designs are covered elsewhere on this site: vehicle roofs in the article on the solar car roof, and satellites in the guide to space solar cells.
How to read a record claim
A headline such as “world record” needs four checks before it can be compared with anything else.
- Cell or module. A small cell and a large module are separate categories, with different minimum areas in the efficiency tables.
- Light. A result under concentrated sunlight, like the 665-sun figure above, is not comparable with a result at one sun.
- Junctions. A single-junction cell is judged against the 33.7% ceiling, while a tandem or multi-junction cell is judged against a higher one.
- Independence. The test must come from a recognised laboratory such as NREL or Fraunhofer ISE CalLab, not from the maker alone.
A laboratory record also says nothing about how long a cell lasts or what it costs. A record cell is a research device, and how a cell performs over years of outdoor use is a separate question.
Frequently asked questions
Is the highest efficiency the same as the best solar panel?
No. Records are set on small research cells or on single laboratory modules. Panels sold to customers differ in size, cost and expected lifetime, and the record tables treat cells and modules as different categories.
Who decides that a result is a record?
An independent, recognised test laboratory measures the device under standard conditions, and the result is then listed in a register such as the efficiency tables or the NREL chart. The maker’s own measurement is not enough.
Why do records for the same technology differ between sources?
Registers use different rules for cell area, light concentration and cell versus module. A figure can also be superseded between publication dates, so each number belongs with its date and category.
What is the standard temperature for measuring a cell?
Laboratories hold the device at 25 °C, together with an AM1.5g spectrum and 1000 W/m2 irradiance, following the IEC 60904-1 standard described by the PV reference above.
