Hydroelectricity is the second most important renewable energy source after solar energy in Japan with an installed capacity of 50.0 gigawatt (GW) as of 2019. According to the International Hydropower Association Japan was the world's sixth largest producer of hydroelectricity in 2020. Most of Japanese hydroelectric power plants are pumped-storage plants. Conventional hydropower plants account for about 20 GW out of the total installed capacity as of 2007.