Solar PV. Decreasing prices and generation cost.

Over the last 20 years, PV has already shown impressive price reductions, with the price
of PV modules decreasing by over 20% every time the cumulative sold volume of PV
modules has doubled. System prices have declined accordingly; during the last 5 years
a price decrease of 50% has been achieved in Europe. System prices are expected to
decrease in the 10 coming years by 36-51% depending on the segment.
Importantly, there is a huge potential for further generation cost decline: around 50%
until 2020. The cost of PV electricity generation in Europe could decrease from a range
of 0.16-0.35 €/kWh in 2010 to a range of 0.08-0.18 €/kWh in 2020 depending on
system size and irradiance level.

Source: European Photovoltaic Industry Association - Solar PV competing in the energy sector