Having recently bought a home in southern CT, we figured we'd check out solar panels as a way to not be so dependent on the grid. Also, we wanted to explore storing this energy in batteries so that we could perhaps become 100% off the grid with regard to electricity.
So we had Solar City do the site inspection for us and they determined that due to the fact that most of our roof is east/west facing (as opposed to the more desirable south-facing roof), we would only be able to supply 42% of our electrical needs with solar panels.
So we said no dice. However, for months, the Solar City people kept calling with high-pressure tactics to get us to change our minds. While it did not make economical sense for us, it evidently did make sense for Solar City as they were getting government subsidies for every installation they did.
Finally I flat out asked them whether it would make sense for them to install these panels if the government subsidies went away and they had to admit that this was the case.
SolarCity is one of the best examples of tax break grubbing. The entire business model of SolarCity is gerrymandered to collect tax breaks and subsidies, not to provide value to their customers. They lease the solar panels to you, and in that way, they are the owners of the panels, and all the government benefits go to them, not the customer. There is very little benefit to being a SolarCity customer.
As for Tesla, it gets by on two big tax breaks. One is that California requires electric vehicle credits, which he sells to other car companies. The second is they get a tax break for offering a car that can be recharged in a few minutes, hence his "battery swap" show last year. The battery swapping will never actually be implemented, but that isn't required by the writers of the tax break.
SpaceX, however, is largely legit. SpaceX got some seed money early on, but no more than others that signed up for the program. SpaceX has grown because they legitimately have a better product.