It all started in the middle of May, when American energy officials were conducting routine security assessments by stripping down a shipment of Chinese solar power inverters connected to electrical grids. They discovered something alarming — weird communication equipment that was not listed in product documentation or specifications.

Then Denmark found “suspicious” components in Asian circuit boards that were supposed to be built into the country’s green energy infrastructure, including the solar inverters and batteries that send electricity to the national power grid. 

Most recently, both Japan and South Korea opened investigations into their China-made solar panels over fears that they, too, may contain hidden communication devices.

American officials say the rogue electronics in the shipment of solar panels and batteries from China could be “kill switches” capable of remotely shutting down parts of America’s power grid, according to the Sunday Times.

The timing of the discoveries and the probes has taken on new significance given the widespread blackouts late last month in parts of Portugal and Spain, countries that rely heavily on solar energy equipment manufactured in China.

Members of Congress have taken notice of the reports. “The threat we face from the Chinese Communist Party is real and growing. Whether it’s telecom hacks or remotely accessing solar and battery inverters, the CCP stops at nothing to target our sensitive infrastructure,” Congressman August Pfluger said this month.

Inverters are the most important components of solar power systems, converting direct current electricity into the type, alternating current, that can be used in homes and factories. They are also found in batteries, heat pumps, and electric vehicle chargers. While the inverters often allow remote access for updates and maintenance, firewalls are usually installed to prevent direct communication with China.

But the unexplained communication components found in the imported inverters in the United States were “not listed in product documents,” two sources told Reuters. “The rogue components provide additional, undocumented communication channels that could allow firewalls to be circumvented remotely, with potentially catastrophic consequences.”

A former director of the National Security Agency, Mike Rogers, told the news agency that China could be counting on the fact that countries building out renewable energy sources have few sources for such equipment other than China. “We know that China believes there is value in placing at least some elements of our core infrastructure at risk of destruction or disruption,” he said.

Several legislative actions are already under way in the United States, including a House bill called the “Decoupling from Foreign Adversarial Battery Dependence Act.” The legislation would ban the Department of Homeland Security from buying batteries from specific Chinese entities, but it would not go into effect until October 2027.

Similar concerns have emerged in other countries. Danish renewable energy firms recently flagged suspicious components found in what they described only as “East Asian” circuit boards intended for green energy infrastructure. 

Green Power Denmark, representing 1,500 companies, described it in a statements as “a clear warning: threats to energy security can hide in plain sight. The real danger isn’t always sabotage. It can also be unlisted components. Hidden functions. That’s why Danish energy companies dismantle and inspect before anything goes live.”

The group’s technical director, Jorgen Christensen, said it is not yet known if the components were installed on purpose or by accident. “It’s possible the supplier had no malicious intent,” he told Reuters. “We can’t say at this point. But that doesn’t change the fact that these components shouldn’t be there.”

South Korea has also taken steps amid the growing concerns following the disclosures from the United States. The country’s trade, industry, and energy ministry recently held discussions with domestic solar firms — including Hanwha Qcells and Hyundai Energy Solutions — to assess potential risks associated with Chinese-made inverters.

Japan has also launched an investigation into Chinese-made solar panels to see if they contain hidden communication devices capable of interrupting the nation’s power grid. “For too long the Japanese government has had no real policy on imports, so this is something of a wake-up call,” a professor of politics and international relations at Tokyo’s Waseda University, Toshimitsu Shigemura, told one news agency.

Other nations have already taken action. Lithuania passed legislation blocking remote Chinese access to renewable energy installations that handle more than 100 kilowatts of electricity, while Estonia has moved to set restrictions to smaller rooftop solar installations.

The Chinese government has rejected claims that its technology poses security threats. “We oppose the generalization of the concept of national security, distorting and smearing China’s infrastructure achievements,” a spokesman for the Chinese embassy told Business Standard.

The U.S. Department of Energy has yet to publicly announce findings related to the suspected components but emphasized the importance of understanding product capabilities fully. “While this functionality may not have malicious intent, it is critical for those procuring to have a full understanding of the capabilities of the products received,” a DOE spokesman told Reuters.