Tesla CEO Elon Musk says while the company recently delivered its 250,000th Tesla, it is experiencing a slowdown at the Gigafactory east of Sparks.

In a letter to investors, he says, “to date, our primary production constraint has been in the battery module assembly line at Gigafactory, where cells are packaged into modules…the combined complexity of module design and its automated manufacturing process has taken this line longer to ramp than expected.” 

As a result Musk says two areas of the Gigafactory had to be resigned by Tesla with hopes of producing 5,000 Model 3 cars per week by the first quarter of 2018.

Portions of the Gigafactory are still under construction with completion in 2020. It’s located at the Reno-Tahoe Industrial Park in Storey County.

Last week Musk tweeted a photo of him on the roof of the Gigafactory. He tweeted, “Btw, just want to express a word of appreciation for the hard work of the Tesla Gigafactory team. Reason I camped on the roof was because it was less time than driving to a hotel room in Reno. Production hell, ~8th circle …