The "Kai-no-kuni Mega Solar Station" in Kofu City, Yamanashi Prefecture, Japan, is a mega- (large-scale) solar power plant with an output of about 1MW that utilizes the rooftop of a warehouse (Fig. 1).

Fig. 1: Rooftop utilized at warehouse in Kofu City (source: Saito Warehouse)

This plant has encountered various phenomena such as "heat insulating effect resulting in air conditioning cost reduction," "toughness proven in the strong winds of a typhoon" and "unexpected heavy snow" over the last about six years since it started selling power in June 2013. These stories were covered in Part 1.

All these phenomena were unexpected when the project was formulated and mostly unique to those undertakings that utilize the roofs of large-scale facilities, in particular, among solar power plants that have a short history. Therefore, they seem to serve as useful references for rooftop solar plants across Japan.

The rooftop mega-solar plant in Kofu City (hereinafter, Kofu Warehouse) was developed and is run by its power producer Saito Warehouse Co Ltd (Chofu City, Tokyo). A total of 4,354 solar panels were arrayed on the rooftop of Kofu Warehouse near Route 140 (Fuefuki Line) running from Kofu Minami Exit on the Chuo Expressway in the direction of Isawa.