For decades it was research institutions that held solar cell efficiency records but significant investment in technology development by solar cell manufacturers means solar companies now lead in improvement of solar cell processing. Instead, ACAP and other research institutions focus on longer-term prospects in new materials and compositions that have higher energy conversion potential, and are cheaper and more sustainable.
In an interview with PV Tech during the SNEC conference in Shanghai in June this year, ACAP Founding Director Martin Green noted that the University of New South Wales held the solar power conversion efficiency record of 25% for around 15 years, before a series of newer players took the lead.
Green said, “Companies have become increasingly sophisticated in their ability to make nice cells. In recent years. the major manufacturers – the Chinese-based manufacturers, largely – have taken over the lead in the quality of cell processing”.
Martin Green’s Solar Efficiency Tables
Comparing world-wide progress on advancing the energy conversion efficiency of various types of solar cells and modules is not ‘apples and apples’, which is why Professor Green leads an international group of experts that publishes a regular report detailing all the highest independently confirmed efficiencies for various types and sizes of solar cells and modules.
The report has been published every 6 months since 1993 and the latest version, Solar Efficiency Tables (Version 64), has 19 new entries since January 2024.
Many of the results reported reflect small, research scale cells or manufacturing prototypes, that are not commercially available as solar modules, but point to future potential of solar technologies.
Guidelines for inclusion in the Tables are available and include a requirement for independent verification of results by a recognised test centre.
The standardised reporting has made this report the world’s most authoritative and accepted reference point. Tabled results are reported for cells and modules made from different semiconductors and for sub-categories within each semiconductor grouping.
You can read more about the methodology in Professor Green’s article about the Solar Cell Efficiency Tables in Nature Reviews Physics.
Highlights of progress as reported in Solar Efficiency Tables (Version 64)
The latest update of the Tables, published in July 2024, reports progress by material type and cell size, with some significant improvements since the last release.
LONGI’s 27.3% efficiency for a large area (243cm2) n-type silicon heterojunction interdigitated-back-contact (HBC) solar cell
The high efficiency is a significant step forward in silicon solar technology, providing a benchmark for future developments in this area. The cell design features both electrical contacts on the rear surface, which minimises energy losses that typically occur when contacts are placed on the front surface. It helps capture more sunlight and improve efficiency.
LONGI’s 34.2% efficiency for perovskite-silicon tandem solar cell
LONGI achieved this before reporting a 34.6% efficiency at the SNEC conference in Shanghai in July 2024. Both are records for this type of cell.
JA Solar’s 25.6% efficiency for large-area n-type TOPCon cell
TOPCon (Tunnel Oxide Passivated Contact) technology is advancing making it possible to produce more efficient and larger solar panels. The TOPCon cell is processed at high temperature.
LONGI’s 26.8% efficiency for large-area n-type silicon cell
This result represents a significant efficiency for large-area silicon cells. This result demonstrates better performance at larger scales, and potentially a lower cost of electricity. This cell is a 'heterojunction cell' processed at low temperature, which is an advantage over the TOPCon cell (above) which is processed at high temperature.
Maxeon’s 24.9% efficiency for silicon IBC solar module
This efficiency was achieved by Maxeon with their interdigitated back contact (IBC) crystalline silicon solar module. IBC technology places all electrical contacts on the rear side of the cell, mitigating hotspot risk, reducing shading losses and increasing efficiency.
First Solar’s 22.6% efficiency for cadmium-telluride (CdTe) cell
This result represents a high efficiency for a small-area CdTe cell, a type of thin-film solar cell known for its cost-effectiveness and suitability for large-scale installations. Advances in CdTe technology help improve the competitiveness of thin-film solar cells against traditional silicon-based cells.
Chinese Academy of Science’s 15% efficiency for small-area CZTSSe cell
CZTSSe is a promising material for thin-film solar cells due to its low cost and abundance of materials. Achieving 15% efficiency is a significant milestone for a small-area kesterite (CZTSSe) cell technology.
UNSW’s 12.1% efficiency for a small-area CZTS thin film solar cell
This efficiency is significant for kesterite solar cells, which are known for their potential as a low-cost, thin-film solar technology. It is notable is that this is a pure sulfide cell, not requiring Se, which is a relatively scarce material that has some associated toxicity issues.
Microquanta’s 15% efficiency for full-sized perovskite module
Microquanta, founded by former UNSW students, developed a full-sized perovskite module with 15% efficiency. Perovskite modules are known for their potential to achieve high efficiencies at a lower cost compared to traditional technologies. This achievement demonstrates the scalability of perovskite technology and its potential for broader commercial use.
It's very important to note…
As the industry grows, the rate of change in performance accelerates, with regular announcements by leading players of new records. To allow comparison, attention must always be paid to the technology type, the cell size and whether the measurement is independently certified.
There is also often a delay between announcement and inclusion in the Solar Efficiency Tables. For example, in June 2024, LONGI announced progress in the records documented in Version 64 of the Tables, with a 34.6% (1cm2) perovskite-silicon tandem solar cell efficiency, verified by the European Solar Testing Installation (ESTI), and a 30.1% commercial (212.1 cm2) wafer-level silicon-perovskite tandem solar cell, certified by the Fraunhofer Institute for Solar Energy (Fraunhofer ISE) in Germany. This progress was under embargo until announcements at international conferences and can be expected to appear in the next edition (Version 65).
Thirty years of progress in solar cell efficiency
The graph below shows the trajectory over 30 years, from 1993 – 2023, of the highest confirmed efficiencies (%) for ≥1 cm2 area cells fabricated using the different technologies shown . Recent progress with organic, perovskite and CdTe cells has been most notable, with good progress also with CIGS.
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