In recent months the telecoms giant has had its CFO Meng Wanzhou arrested in Canada, been barred from the construction of 5G networks in the U.K, Australia, and New Zealand, and had a sales director arrested in Poland on suspicion of espionage (Poland is also considering a ban on the use of Huawei products).

Now, suspicion has spread to the Chinese firm’s sideline in solar panels. U.S. tariffs already posed a barrier to Huawei’s entry into the country’s growing solar market, but American politicians now claim the firm’s panels could be sleeper agents for disrupting the U.S. electrical grid.

In October, Democratic congressman Tom Marino wrote to U.S. energy secretary Rick Perry about their concerns, stating Huawei’s cheaper solar panel technology “may pose a threat to our nation’s infrastructure.”

On top of this, legislators introduced bills on Wednesday that would restrict sales of U.S. technology to Chinese telecoms companies in violation of sanctions or export control laws.

In response to the gathering storm, Huawei founder and president Ren Zhengfei Tuesday told reporters that he was ready to fight the mounting charges against his company. Huawei’s chief security officer in the U.S. told the Financial Times, “There is no evidence, and I have never heard any specific allegation that there is any greater vulnerability in our products than anybody else’s.”

Note: The original version of this story listed Democratic congressman Jerry McNerny and Republican congressman Bob Latta as signers of the letter to Perry. They were not and we have corrected the error.