PV Tech’s top five Premium stories of the year in 2025

You can also read here our ten most-read general articles of 2025.

5 – ‘Solar will continue to deliver’

4 August: The fifth most-read Premium article in 2025 is a feature from our journal, PV Tech Power, that looks at the impact of the “One Big Beautiful Bill Act” (OBBBA) and its removal of tax credits for solar PV and wind energy would have in the US in the coming years.

Not only that, but the feature also explored the executive order that US president Donald Trump signed days after the passing of OBBBA, the impact on domestic solar manufacturing and one of the key concerns for the solar industry in general this year and for the coming years: Foreign Entity of Concern (FEOC).

The FEOC rules state that projects directly owned by, under “effective control” of, or receiving “material assistance” from a designated foreign entity (read: Chinese entity) cannot receive the 45X tax credit. China and Chinese-controlled firms dominate over 80% of every stage of the solar supply chain, putting particular strain on the “material assistance” provision.

“These new market distortions could ultimately harm [US] renewable energy deployment while potentially precluding domestic manufacturers from receiving the 45X tax credits due to the FEOC restrictions,” explained Elissa Pierce, research analyst at Wood Mackenzie.

One of the outcomes of this new legislation is that it has created a rush to start building projects, in order to secure tax credits.

“2026 will likely be a big year for putting projects in service,” Christian Roselund, senior policy analyst at Intertek’s Clean Energy Associates (CEA) said. “And then in 2027, the changes made to eligibility for these tax credits will likely start to affect deployment levels. In 2028, all major market analysts expect to see a significant decline in deployment. And after that, the size of the market will depend on what deployment levels look like without the tax credits.”

Even though uncertainty has been the operative word for the US solar industry in 2025,  Abigail Ross Hopper, president and CEO at trade body the Solar Energy Industries Association (SEIA) told PV Tech Power: “Here’s what I know to be true—the solar and storage industry is resilient. Our industry has a value proposition no other sector can match: clean, fast, local power that lowers costs and boosts resilience.

“Americans will still demand energy choices, and the solar and storage industry will continue to deliver them.”

4 – The copper standard: could new cell manufacturing processes replace silver?

15 August: Finding an alternative to silver for solar cell manufacturing has been a challenge that the industry has been focusing on in the past few years. Its high conductivity makes it well-suited for use in cells to transfer electricity, but as the solar industry grows, its silver consumption could create issues. According to the Silver Institute, in 2014, solar cells accounted for 5% of global silver demand. This figure is expected to reach 14% in 2025, putting pressure on the world’s silver supply to meet this demand.

One of the companies working to replace silver with another material is Chinese solar manufacturer AIKO, which this year has started using copper to form interconnections in its all-back contact (ABC) modules. The company’s chief scientist, Yongqian Wang, told PV Tech Premium that copper is a “highly suitable” alternative to silver.

“Copper offers a compelling combination of conductivity, availability, and mechanical strength—making it a highly suitable alternative to silver from a long-term industrial perspective,” said Wang.

In the article, Wang said that copper offers three key advantages: its material characteristics, the abundance of the metal and the maturity of the copper metallisation process integral to its use in solar cells.

When asked about the future of copper in cell production, Wang said that AIKO’s copper process could be applied to other kinds of solar cells, such as tunnel oxide passivated contact (TOPCon) and heterojunction (HJT) cells.

Looking further ahead, he suggested that, should the transition from silver to copper be realised across the industry, the world’s solar supply chains could be disrupted.

“For example, China imports more than 3,000 tons of silver powder annually from Japan and the US, with a total value close to RMB25 billion (US$3.5 billion),” Wang said. “In contrast, the preparation technology for copper oxide powder, the raw material used in the copper process, is very simple and can be entirely produced domestically without imports.”

Wang concluded that in the medium- to long-term, copper processes will inevitably become the standard for BC cells and module products.

3 – Deep concern about TOPCon module quality

24 February: Performance and reliability issues for TOPCon and n-type solar PV modules have been two of the topics we’ve covered extensively in 2025. So much so that we did a review of that topic here for our year-end coverage.

In this Premium article, Chinese academics Wenzhong Shen, Sheng Ma and Huanpei Huang presented an overview of the phenomena, mechanisms and solutions surrounding ultraviolet-induced degradation (UVID) that have emerged in both academia and industry.

According to recent reports, the mechanism underlying UVID in PV modules is primarily linked to the properties and behaviour of the passivation layer. Different types of solar cells employ distinct passivation structures, leading to variations in the susceptibility to UVID varies across technologies.

Among the potential solutions proposed by the authors is the optimisation of the passivation structure and the use of suitable packaging materials. For a long-term solution, the focus should be on developing innovative materials and exploring new technologies, including advanced passivation techniques.

The creation of a large database compiling stability data from different PV technologies can also facilitate a better understanding of their long-term performance in real-world conditions.

Sharing this data among researchers and manufacturers can drive improvements across the industry. Building more robust models to analyse UVID mechanisms will provide deeper insights into how different materials and technologies react to UV irradiation.

2 – Solar supply chains under the microscope: navigating Europe’s evolving ESG compliance landscape

18 November: This Premium interview came as part of our coverage of ModuleTech Europe, held in Málaga, Spain, in December 2025. PV Tech spoke with George Touloupas, Intertek CEA’s vice president of environmental, social and governance (ESG) and new services, about solar supply chain compliance in Europe and the challenges to reach ESG compliance.

“Although it all started four years ago in the US with the UFLPA (Uyghur Forced Labor Prevention Act), it very quickly spilled over to Europe,” explained Touloupas, adding:

“Europe was already moving in a similar direction, but that was like a spurring action. Things have progressed quite a bit, and this kind of due diligence is becoming standard in the US and in Europe.”

Multiple European frameworks are converging to create a comprehensive oversight system that extends far beyond the solar industry. These include among others the Carbon Border Adjustment Mechanism (CBAM), the CSRD (Corporate Sustainability Reporting Directive) and the CSDDD (Corporate Sustainability Due Diligence Directive). At the country level, Norway, Germany and the UK have also implemented regulations towards building a solar supply chain compliance framework.

Touloupas explained that the industry has been much more proactive and getting ahead of regulation “to avoid unnecessary risk”.

1 – GCL backs FBR over Siemens process to ‘remain competitive’ in cutthroat polysilicon industry

2 April: The most-read Premium article in 2025 focused on polysilicon production. More specifically, Chinese polysilicon producer GCL Technology refocused its manufacturing processes following sustained challenges in the polysilicon market.

The company also exited its remaining investments in the Xinjiang Uyghur Autonomous Region (XUAR) of China. GCL withdrew its indirect shareholding in silicon rod manufacturer Xinjiang Goens, previously held via its subsidiary Jiangsu Zhongneng.

This meant that GCL had “redirected its focus” away from the XUAR to its four 100,000-ton granular polysilicon production bases across China: Xuzhou (Jiangsu), Leshan (Sichuan), Hohhot and Baotou (Inner Mongolia).

This move also meant that the company “fully exited” direct and indirect investments into the Siemens method of polysilicon production in favour of Fluidised Bed Reactor (FBR) granular polysilicon production, which is more cost-effective and uses less energy than the Siemens process.

The changes were announced following a challenging year for the company and the broader polysilicon manufacturing industry, with prices below RMB40/kg (US$5.7/kg) for most of 2024 and the beginning of 2025.