The database is a compilation of existing cost data for wind, solar
photovoltaic (solar PV), solar thermal (CSP), and geothermal energy
technologies, including historical costs and projected costs for each.
The data sources and references used to compile this information are
included, as well as the experts that were consulted in identifying
sources. The database separates information collected from primary and
secondary sources. Often, data collected for one study is recycled into
another, which is further referenced elsewhere, and so on. Identifying
which sources are based on original data collection and which relied on
previous work should be useful information.