I have to admit that reading their difficulties with the solar roof in the press, and their own statements about their installation and solar roof manufacturing issues in their 10-Q and 10-K, I am becoming much less sanguine about the longevity of the solar roof. Their comments about the mismatch between the scale of the factory and the actual number of their roof installations implies to me high fixed costs, and the installation process does not appear to be low cost either, given the manpower and time it appears to take and the project management issues that appear to plague some installs. So while scaling up solves the fixed costs issue, it makes the variable costs of roof installations worse. The recent dramatic repricing of solar roofs suggests that the one or both costs were way off, as does the reported profit margin drop.
I am not saying that roofing is an easy business; I don't think that it is. I do think that customer service gives a business a great way to track product (and installation) quality, because without feedback, and quality metrics, I have found that it is hard to improve.
I do wonder whether their business model might be better served by focusing on solar tile manufacturing and leaving the installation to experienced roofing contractors. Just a thought.
As
@jimm01 posted above, the solar roof while solving an esthetic issue goes the other direction from a product that scales well for mass market roofs, which might be better served by, say, monolithic large panels that could be quickly placed by a small crane.
As much as I like Tesla's products, and I do, I don't think that they are out of the woods yet by a long shot, their stock price and market capitalization notwithstanding.
All the best,
BG