Well first off, I don’t see a time range here. This could easily be stretched over multiple years.

Secondly, if someone says “tens or hundreds of millions”, I assume that they’re giving a rough estimate based on incomplete information. If I’m evaluating the credibility of such an estimate, then I’ll consider the most conservative end of the range, which in this case is $20M. If we suppose that that was spread over three years, then we’re talking about 1-2% of total revenue. That doesn’t sound so implausible, right?

Finally, SolarCity’s 2016 revenue was $730M, not $400M.