This New York Times article outlines the decline and credits the Brookings Institution, The World resources foundation, and The Breakthrough Institute. They jointly authored the following report “Beyond Boom and Bust” that details the decline and policy changes that they argue would make for a more sustainable subsidy regime.  Unfortunately the current political situation does not bode well for reform, particularly if it costs money. 

The current subsidy regime is boom and bust and not focused on technology improvement.  It is classic government subsidies that encourage the status quo and create a class of companies that live on the subsidies without incentive to improve and who lobby to maintain the subsidies regardless of the benefit or lack thereof.  It also funnels money to favored constituencies like government contractors and peer reviewed scientists.  

The main focus should be on technologies that have a realistic chance of economic viability with an honest accounting of costs associated with intermittency and geographic isolation.  Too much of alternative energy is over optimism and pass the buck accounting.