> The purchase makes no real sense, unless you bend over backwards to try to force a rationalization.

Makes plenty of sense. SolarCity has a failing business model, but they have a nice facility in the works. Tesla Energy makes batteries that right now are only appealing to commercial players. If they combine the two in a good way, they may be able to make a product that's appealing to the consumer. As with any purchase, it all depends on how it'll be executed.

This is weird by American standards, but there are plenty of conglomerates who have their hands in many industries. Samsung, Hyundai, Mitsubishi, etc.