During the decade from the late 1990s to the late 2000s, successive Spanish governments of different parties developed and refined a generous system for promoting investment in renewable power. This support system, the “special regime,” was based primarily on a combination of regulated tariffs and premiums on top of the market price of electricity that facility owners could choose between. It was designed to ensure that investors would receive a reasonable return on their investments while trying to minimize the financial burden on electricity users, who would ultimately pay the costs of the support system. Under the special regime, Spain saw its first significant buildup in renewable generating capacity and electricity output, first in wind power and then in solar.