Are the Recent Declines in Solar PV Module Prices Sustainable?

Once dismissed as unrealistically expensive, solar photovoltaic (PV) power has been on a remarkable run lately: according to Bloomberg Professional Service, in comparison to the start of the decade, the annual installations of new solar PV power capacity have doubled. This expansion reflects in large part a dramatic decline in module prices from over $4 per Watt (W) at the beginning of 2008 to under $0.8/W by the end of 2013. In 2010, Richard Swanson, the founder of SunPower, documented that over the previous three decades the average sales prices of PV modules had conformed closely to a so-called 80% learning curve, that is, module prices declined by close to 20% with every doubling of the cumulative number of modules produced. However, recent solar module prices have not exactly followed the “Swanson curve.” In 2008 and 2009, module prices were above the benchmark predicted by the learning curve, a phenomenon widely attributed to a temporary shortage of polysilicon. Then, beginning in 2011, the situation reversed: price declines have been noticeably steeper than those predicted by the learning curve. This observation has raised several questions among industry analysts. Did these steep declines reflect accelerated cost reductions or potentially excessive additions to manufacturing capacity in recent years? Further, what price dynamics can be expected going forward, and what do these trends imply for public policy support for solar power?