Another day, another reason why fossil fuels are toast. Persistent innovation in the global solar industry has already sent the conversion efficiency of solar cells through the roof over the past 25 years, and there’s plenty more where that came from. Last week two more world efficiency records were set, one for solar modules made with triple III-V germanium cells, and the other for modules made with tandem perovskite-silicon cells.
For those of you new to the topic, solar modules are the intermediate step between solar cells and solar panels.  Typically, solar modules are comprised of 60-72 connected cells, though some use much less. Regardless of the number of cells, those connections can have a significant impact on the conversion efficiency of the finished module, with a ripple effect into the efficiency of the finished solar panel.
CleanTechnica took note of the new germanium solar record over the weekend, consisting of a 34.2% conversion efficiency reported by the Fraunhofer Institute for Solar Energy Systems in Germany, for a module measuring 833 square centimeters made up of triple III-V germanium cells.
To recap briefly, the Fraunhofer team used a new technique to connect its solar cells directly to each other, bypassing conventional module fabrication methods that deploy solder-coated copper ribbons. “By eliminating cell interconnects, no active cell area is shaded,” the researchers explain.
“The resulting exceptionally high area utilization was a key factor in achieving the record efficiency,” they emphasize.
Considering the topsy-turvy state of federal energy policy, it would not be a surprise to see US research institutions and private sector innovators lose funding for next-generation solar equipment like the new Fraunhofer module. Nevertheless, some projects continue to trickle through the pipeline, and the Department of Defense is one reason why.
In a curious turn of events, the Trump administration has continued to support a germanium supply chain project initially funded by the Biden administration. Back in April of 2024, the DoD awarded $14.4 million from the Defense Production Act Investment Program to 5N+ Semiconductors. The firm was tasked with increasing the production of germanium substrates, for use in the solar cells deployed on military and commercial satellites.
In January of this year, the Department of Defense — which now calls itself the Department of War — upped the ante with a Defense Production Act award of $18.1 million to the same company, focused on increasing “optics and solar germanium crystal supply chains” in the US.
“Increasing domestic germanium production is one of the highest industrial base priorities for the DoW,” explained Assistant Secretary of War for Industrial Base Policy Mike Cadenazzi in a press statement.
“Makers of defense applications use germanium in infrared optics, night vision systems, surveillance windows, individual thermal weapon sights, and other electro-optical/infrared (EO/IR) equipment. Germanium is also essential for solar cells that power military and civilian satellites,” the Defense Department added.
Interesting! If you have any thoughts about that, drop a note in the discussion thread. Turning now to the tandem perovskite-silicon module, the world record in that category goes — at least for now — to the leading Chinese firm Trinasolar. It’s the latest in a string of notable achievements for the company, which claims a total of world 41 records set or broken in the solar industry.
On June 9, Trinasolar announced a conversion efficiency of 29.2%, verified independently by the certification institute TÜV SÜD for its tandem perovskite-silicon solar module. The company also notes that the new module has a power output of 907 watts, a significant increase over its next-best effort of 808 watts last year.
More to the point, Trinasolar also emphasized that the record-breaking module is sized for, and compliant with, industrial applications. Although that doesn’t necessarily mean the labwork is market-ready next week, it does indicate that commercial development is in the works.
The Trinasolar news is also significant because it represents the steady march of perovskite technology into widespread use. Perovskite is a relatively inexpensive synthetic optical material with the potential to launch a new generation of lower-costing, higher-performing solar cells.
With higher performance, solar developers can squeeze the same amount of clean kilowatts from less space, resulting in costs savings far beyond the factory walls. Land acquisition, site preparation, labor, and operating/repair expenses are among the factors that also shrink. All else being equal, end-of-life disposal, recycling, and recovery costs are also reduced.
Though fragile in the raw, perovskites can be combined with other materials to support the durability factor. In a tandem perovskite-silicon setup, silicon adds the sturdiness while perovskites lend a conversion efficiency boost. The result is a more efficient, less costly product overall.
Despite the sharp U-turn in federal energy policy, US innovators in the perovskite solar cell field have hardly been asleep at the wheel. A case in point is California-based Tandem PV.
The startup is among the firms applying a thin layer of perovskite onto silicon solar cells to enhance performance and cut overall costs. In March, the startup celebrated its place on TIME’s America’s Top GreenTech Companies of 2026, its third consecutive such recognition.
Tandem PV has also been a regular visitor to the pages of CleanTechnica over the years, most recently in January when former Energy Secretary (and newly tapped Tandem PV board member) Jennifer Granholm remarked that the company was on track to hit the 30% conversion efficiency mark for its perovskite-silicon solar panels.
At present, the panels are at 29.7% efficiency, which Tandem states is 30% more powerful than typical silicon solar panels.
“Solar has reached an inflection point where the market is demanding not just lower-cost clean energy, but bigger leaps in performance, resilience, and domestic capability,” Tandem CEO Scott Wharton explained in a press statement.
Wharton wasn’t just talking out of his hat. In April, Tandem launched a demonstration factory in Fremont, California that places it one giant step closer to volume production for commercial markets.
“The 65,000-square-foot Fremont site is producing tandem solar panels using state-of-the-art equipment. The line has approximately 40 MW of annual nameplate capacity, and the panels are roughly 60 times larger than Tandem PV’s R&D-scale devices,” the company reported.
“The line is designed to demonstrate that perovskite-silicon tandem panels can be manufactured reliably in the United States at scale with high power density, durability, and lower costs,” Tandem emphasizes.
Next steps for the company include validating a performance of 25 years or more, in accord with warranty requirements for utility-scale solar among other industry standards.
Hold on to your hats. The Fremont factory is already turning out modules that will be sent to customers for validation trials later this year, towards the goal of closing the first sales before year’s end. If all goes according to plan, full volume production will begin in 2028.
Photo: Despite the sharp U-turn in US energy policy, global innovators like China’s Trinasolar are continuing to set new records for solar conversion efficiency (screenshot, courtesy of Trinasolar).
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Tina has been covering advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters for CleanTechnica since 2009. Follow her @tinamcasey on LinkedIn, Mastodon or Bluesky.
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