Malfunctioning Tesla solar panels started fires at “no fewer than” seven Walmart stores, resulting in hundreds of thousands of dollars in damage, the retail giant alleges in a new lawsuit filed in New York State Supreme Court Tuesday. The lawsuit was first reported by Bloomberg.

Walmart alleges that “years of gross negligence” and “failure to live up to industry standards by Tesla” sparked the blazes and led at least seven locations to close temporarily over the last seven years. Representatives for Tesla did not immediately respond to a request for comment.

“the occurrence of multiple fires involving Tesla’s solar systems is but one unmistakable sign of negligence”

Tesla has installed solar panels at more than 240 Walmart locations, but lawyers for the retailer write in the complaint that “the occurrence of multiple fires involving Tesla’s solar systems is but one unmistakable sign of negligence.” Walmart alleges in the suit that Tesla didn’t ground its systems properly, that the solar panels installed at Walmart sites were defective, and that Tesla didn’t keep proper documentation of the systems.

According to Walmart’s suit, the problems started with SolarCity before Tesla acquired the solar panel company in 2016. SolarCity had “adopted an ill-considered business model that required it to install solar panel systems haphazardly and as quickly as possible in order to turn a profit, and the contractors and subcontractors who performed the initial installation work had not been properly hired, trained, and supervised.”

Walmart claims that Tesla has failed to provide a complete set of “final ‘root cause’ analyses needed to identify the precise defects in its systems that caused all of the fires.”

“The number of defects, however, is overwhelming and plainly indicative of systemic, widespread failures by Tesla to meet the standard of care, as set forth in the governing contracts, as to the solar systems installed at Walmart’s stores,” lawyers for Walmart write.

Walmart says it “demanded” that Tesla disconnect all of its solar panels after three fires broke out in 2018 in Ohio, Maryland, and California. Tesla complied, according to the complaint, but Walmart says another fire broke out anyway at a second California store.

The news comes just a few days after Tesla relaunched the website for its residential solar program and announced a new rental option.