Energy might take more time to mature (vs EVs) because of headaches involved to install + bad wrap from the past. My experience on the process led me through decisions on our solar/battery sizes without proper guidance from Tesla. All to be worked out eventually, but too early to tell WHEN the proper value will be realized.
Then when you consider that only 3 homes per day doing solar homes in Az (possibly every 2 days in practice), it's hard to realize much value here near-term. California 2020 new roof laws will accelerate the growth, but compared to how many cars are sold (with comparable margins and cash flow per sale), this will take a while to realize.
But then I put on my future optics and energy in general is HUGE $$$. And as cars demand more and more electricity vs gas, the solar demand will also rise. I'm already wishing I had more panels now so I could cover EV charging as well. Basically, EVs are creating more demand for Solar.
It's never straight line with anything Tesla, so I have no clue when solar will be significant. Maybe end of next year with the greatest drop in Fed tax credits from 26% to 10% in the US. We'll know better this time next year. (I'm ignoring Mega power installs here, but those are scarce so far but important in the long run.)