A complaint from a whistleblower prompted the US Securities and Exchange Commission (SEC) to investigate.
Steven Henkes, a former field quality manager for Tesla, alleges the company failed to properly notify shareholders and the public about the risks.
Tesla solar systems have been known to catch fire in a small number of cases.
Mr Henkes’s complaint, filed more than a year ago, alleged Tesla had failed to properly disclose defects with some electrical connectors could cause fires and instead told customers it had had to carry out maintenance to prevent a problem shutting down the solar-panel systems.
“We have confirmed with Division of Enforcement staff that the investigation from which you seek records is still active and ongoing,” the SEC told Mr Henkes, in a letter the Reuters news agency said it had independently verified.
Steven Henkes has sued Tesla over his dismissalThe SEC made clear in its letter the investigation should not be taken as confirmation there had been any legal violations.
Mr Henkes was fired from Tesla and sued the company over his dismissal.
Shares in the company fell by more than 6% shortly after news of the SEC’s investigation was published, though they have since risen again slightly.
Alleged fire safety issues with Tesla’s solar panels have been reported before.
In 2019, US retailer Walmart sued Tesla over fires at seven outlets where the panels had been installed.
The legal action was later dropped, following a settlement agreement.
Tesla abolished its public-relations department in 2020, so could not be contacted for comment.
