The power plant is being built on a reservoir in Japan's Chiba prefecture and is anticipated to supply enough electricity for nearly 5,000 households when it is completed in early 2018.

Space-starved Japan has already seen several floating solar farms built as part of the country's drive to exploit more renewable energy in the wake of the 2011 Fukushima disaster. The shutdown of nuclear plants has seen Japan increasingly reliant on fossil fuel imports that have hit its emissions-cutting ambitions.

The Yamakura dam power plant will see more than 50,000 solar photovoltaic panels cover a 180,000 m sq area, but compared to other land-based plants it is relatively small. At 13.7MW when finished, it would not make the top 100 of the world's largest solar photovoltaic farms.