That's an easy dream to sell, but I don't buy that home rooftop solar and batteries will be cheaper for consumers than something at scale. The downside is centralized production needs transmission infrastructure, but that's already built, and between centralized installation and maintenance and a better location, the mass approach seems better.

The only legitimate synergy between Tesla and SolarCity is that they target the same sort of people--a Tesla owner is probably more likely to have rooftop solar than a F-150 owner, or even an Accord owner.