Japan needs to import about 90% of its energy requirements. Its first commercial nuclear power reactor began operating in mid-1966, and nuclear energy has been a national strategic priority since 1973. This came under review following the 2011 Fukushima accident but has been confirmed. Up until 2011, Japan was generating some 30% of electricity from its reactors, which was expected to increase to at least 40% by 2017. The plan is now for at least 20% by 2030 from a depleted fleet. The first two reactors restarted in August and October 2015, with a further eight having restarted since. 16 reactors are currently in the process of restart approval.

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.

In Japan’s electricity sector wind power generates a small proportion of the country’s electricity. It has been estimated that Japan has the potential for 144 gigawatts (GW) for onshore wind and 608 GW of offshore wind capacity. As of 2019, the country had a total installed capacity of 3,923 MW. As of 2018, government targets for wind power deployment were relatively low when compared to other countries, at 1.7% of electricity production by 2030

Solar power in Japan has been expanding since the late 1990s. The country is a leading manufacturer of photovoltaics (PV) and a large installer of domestic PV systems with most of them grid-connected Japan has insolation of about 4.3 to 4.8 kWh/(m²·day).