Yes, there are 10,000 people on a waiting list for the Solar Roof. It's not that people don't want to buy it, Tesla just isn't currently fulfilling orders.

EDIT: 11,000 reservations through May 2018 according to Bloomberg, currently it’s $1,400 to reserve.

Can you please provide a source for that. That sounds like material information, but I couldn't find any mention of this in their last quarterly report.

Aforementioned Bloomberg article - https://www.bloomberg.com/news/features/2018-11-20/inside-el...

Quoting - On the other hand, Tesla had received about 11,000 customer orders for Solar Roof by May, a backlog that was both encouraging and daunting.

Has there been a down payment associated with getting on the waiting list?

It probably means that they are failing to provide the product. I have no real information, but my best bet for how this situation came about (handful of installations, growing very slowly, yet with no news after a large splash on initial announcement) is that the tiles are not durable enough to last the lifetime of the roof.

That would be something that could come out of the left field, surprising them after announcement, and the slow trickle of installations is them attempting to iterate the product and make it better.