Fjone Power Plant is located in Nissedal municipality on the banks of Nisser lake. The power plant utilises a 258-metre waterfall between the lakes Napevatn and Nisser.
In 1967, the former Vestfold kraft was granted a licence to develop Fjone Power Plant and the development was completed on 10 April 1970. This was the first power station that Vestfold kraft developed itself and that was wholly owned by the company.
Napevatn is the main reservoir for Fjone Power Plant. A pump was built by Rolleivstadvatn lake in 1969 with two machines, each at 0.15 MW, which pump water up into Sandvatn lake. The water then flows down to Napevatn lake. Rolleivstadvatn lake, along with five stream intakes, make up Napevatn’s external inflow.
Owner: Skagerak Kraft AS 100%.