Tesla deployed 109 megawatts of electric-generating capacity during the third quarter, down 42 percent from 187 megawatts a year ago. It was the fewest megawatts of solar generating capacity that the former SolarCity business had deployed since the second quarter of 2014.

"We do expect solar demand to rebound as we move solar sales to our stores, which is a more efficient distribution channel," Musk said, during the Wednesday conference call. The launch of the company's solar roof also is expected to become a significant part of Tesla's solar energy sales because it is geared toward consumers who need a new roof or are building a new home, as opposed to conventional rooftop solar, which is limited to consumers with roofs that are relatively new and in good shape.

The solar roof and Tesla's shrinking solar business were overshadowed by Tesla's bigger-than-expected loss and its announcement that the production ramp of its more affordable Model 3 sedan will be pushed back. Tesla said it delivered 26,137 cars during the third quarter, but only 222 were Model 3s.

Tesla said its Model 3 production has been hampered by bottlenecks, especially related to its battery pack. Tesla said it now expects to produce 5,000 Model 3 vehicles a week by the end of March, three months later than its August forecast.