This course covers the cost development of renewable energy technologies, which includes the analysis of technological change, in particular with regard to technological learning, the assessment of learning rates of renewable energy technologies available in literature and forecasting studies. For many (energy) technologies, a log-linear relation was found between the accumulated experience and the technical (e.g. efficiency) and economic performance (e.g. investment costs). The rate at which cost decline for each doubling of cumulative production is expressed by the progress ratio (PR). A progress ratio of 90% results in a learning Rate (LR) of 10% and similar cost reduction per doubling of cumulative production (IEA 2000; Junginger, Sark et al. 2010). Learning curves for the renewable energy technologies as well as levelised cost of electricity will be presented. The latter also include the impact of resource conditions (e.g. wind and solar yield) at different locations as well as operation and maintenance costs and fuel expenditures in the case of biomass technologies.