Amazon facilities faced at least a half-dozen fires due to solar panels between early 2020 and mid-2021, CNBC reports, citing company documents that it obtained.

Amazon experienced “critical fire or arc flash events” at six of its 47 North American sites with solar panels, or 12.7% of such facilities, according to CNBC. The company took its solar power systems offline temporarily last year as a result, while repairs were made.

“The rate of dangerous incidents is unacceptable, and above industry averages,” an Amazon employee wrote in one of the internal reports obtained by the news outlet.

Solar panel fires have been a bone of contention at large commercial properties before. In 2019, after a spate of solar panel fires on Walmart rooftops, the company filed suit against Tesla, contending that at least seven rooftop fires were a result of a Tesla subsidiary's alleged faulty installation of solar panels.

Eventually, Walmart dropped its lawsuit in exchange for a settlement that kept more than 240 Tesla solar systems in place at retail outlets. Terms of the settlement weren't disclosed.

The rise of e-commerce is spurring the construction of larger industrial facilities, and larger building use more energy, and the expansive roofs on these buildings can make them ideal spots to adopt solar power systems to provide that energy.

Large buildings are inordinately power hungry. Sortation buildings, distribution centers and other high-throughput facilities rely on computers and other devices to manage their inventory and flow of goods. All of the machines need electricity, and a lot of it.

The U.S. Energy Information Administration reported that in 2012, while fewer than 1% of buildings across commercial property types were larger than 200K SF, they accounted for about 26% of all commercial building energy consumption.

About 11% of commercial buildings measured from 25K SF to 200K SF, and they accounted for about 42% of all energy consumption in commercial buildings.