MIT researchers explain why the cost of solar power is dropping
PV Magazine reported that a new analysis by MIT researchers has pinpointed what caused the savings, including the policies and technology changes that mattered most. For example, they found that government policy to help grow markets played a critical role in reducing this technology’s costs. At the device level, the dominant factor was an increase in “conversion efficiency,” or the amount of power generated from a given amount of sunlight. The insights can help to inform future policies and evaluate whether similar improvements can be achieved in other technologies. The findings are being reported today in the journal Energy Policy, in a paper by MIT Associate Professor Jessika Trancik, postdoc Goksin Kavlak, and research scientist James McNerney.
The team looked at the technology-level (“low-level”) factors that have affected cost by changing the modules and manufacturing process. Solar cell technology has improved greatly; for example, the cells have become much more efficient at converting sunlight to electricity. Factors like this, Trancik explains, fall in a category of low-level mechanisms that deal with the physical products themselves.
The team also estimated the cost impacts of “high-level” mechanisms, including learning by doing, research and development, and economies of scale. Examples include the way improved production processes have cut the number of defective cells produced and thus improved yields, and the fact that much larger factories have led to significant economies of scale.
The study, which covered the years 1980 to 2012 (during which module costs fell by 97 percent), found that there were six low-level factors that accounted for more than 10 percent each of the overall drop in costs, and four of those factors accounted for at least 15 percent each. The results point to “the importance of having many different ‘knobs’ to turn, to achieve a steady decline in cost,” Trancik says. The more different opportunities there are to reduce costs, the less likely it is that they will be exhausted quickly.
The relative importance of the factors has changed over time, the study shows. In earlier years, research and development was the dominant cost-reducing high-level mechanism, through improvements to the devices themselves and to manufacturing methods. For about the last decade, however, the largest single high-level factor in the continuing cost decline has been economies of scale, as solar-cell and module manufacturing plants have become ever larger.
In terms of government policy, Ms Trancik said that policies that stimulated market growth accounted for about 60 percent of the overall cost decline, so “that played an important part in reducing costs.” Policies stimulating market growth included measures such as renewable portfolio standards, feed-in tariffs, and a variety of subsidies. Government-funded R&D accounted for the other 40 percent — although public R&D played a larger part in the earlier years.
Source : Pv Buzz