The solar industry is in the midst of a huge expansion phase, but it's not always a straight line up for all parts of the industry. Utility scale, commercial, and residential solar will ebb and flow as incentives and investment flows to these different areas. 

What's surprising this year is that utility scale solar is performing best of those three. Commercial solar took a step back in the second quarter and residential was flat. That's good news for First Solar (FSLR 1.18%) and SunPower (SPWR 0.85%), who generate most of their profits from these huge projects. But it also highlights how quickly SolarCity (SCTY.DL) is taking share in residential solar. Solar analyst Travis Hoium covers the latest trends in the video below.