Five years ago, when DTE Energy and Consumers Energy launched small pilot programs offering premium rates to customers for power from their solar panels, Oak Electric and Four Elements Energy became very busy installing solar systems on homes and small businesses. But, in 2012, the roof fell in for rooftop solar in Michigan, when the utilities significantly changed their pilots. That happened, installers said, because DTE’s Solar Currents and Consumers’ Experimental Advanced Renewables Program (EARP) drastically cut their rates for new participants, citing sharply falling solar panel prices.