The 55k 75D sales generated around $1.1bn gross profit in 2018
Where are you getting gross margins on the 75D? I have trouble believing that the margins on the 75D are that high. There's only 25kWh difference of cells between a 75D and a 100D ($~4-5k), but the difference in price was a lot more than $4-5k, and that difference was pure profit. I have trouble believing that 75D margins were even double digits.
"Downgrading" people to a P3D probably greatly increases margins. It also leaves the remaining S/X line as very high margin.