It's not wildly far off but I think his battery costs are a stretch. In fact double that would be a challenge to have a quality and reliable system. But it is definitely lass than 3x. Right now the best value for batteries I'm getting is 0.18 per w/h. To get 0.08 you would have to doing something like recycling small cell or ev batteries which isn't necessarily scalable and comes with some risks.

Panel costs are accurate and the additional electronic expense is not super high. $1000 should be enough for most setups.

For most people the issue is space. This is going to be another thing where the poor are taxed. A significant amount of single family residences dropping off the grid will cause prices to go up for the people that don't have the luxury of 4000 sq ft to fill with solar panels.