The law aims to reduce Japan's reliance on nuclear power following the disaster at the Fukushima power plant. It also aims to reduce the country's greenhouse emmissions to 25% of its 1990 level by 2020.
Despite Fukushima, the bill has faced opposition throughout its passage. Initially there were fears a FIT would damage manufacturing competitiveness until a get-out clause was added allowing heavy-electricity users to be exempt from 80% of the charge.
However, one key detail, the price each utility will pay for each form of renewable energy, will not be decided until until next year.
At the end of 2010, Japan had a wind-energy capacity of 2.3GW. This fell short of its own 3GW target for 31 March 2011.
Japan's poor installation record has been blamed on economic issues and the weather conditions caused by the country's mountainous terrain.
According to Windpower Monthly's global market status report into Japan's wind-energy ambitions, the country is looking at developing offshore projects. This includes the wind farms using floating turbines by 2013.