Why is PV Solar Energy getting cheaper and cheaper?
We find that increased module efficiency was the leading low-level cause of cost reduction in 1980-2001, contributing almost 30% of the cost decline. The most important high-level mechanism was R&D in these earlier stages of the technology. After 2001, scale economies became a more significant cause of cost reduction, approaching R&D in importance. Policies that stimulate market growth have played a key role in enabling the cost reduction in PV, through privately-funded R&D and economies of scale, and to a lesser extent learning-by-doing