Mie Kotsu Co Ltd (Tsu City) set up solar-panel-embedded roofs with an output of about 457kW on the parking spaces for large buses at its Yokkaichi Bus Operation Office and started selling electric power on June 7, 2017 (Fig. 1).

Fig. 1: Solar-panel-embedded roofs set up on the parking lots for large buses at its Yokkaichi Bus Operation Office. Mie Kotsu will set up solar-panel-embedded roofs at three operations in series.

It is unusual to set up solar-panel-embedded roofs on parking spaces for large buses.

Mie Kotsu installed solar-panel-embedded roofs at its Chusei Bus Operation Office in Tsu City and its Iga Bus Operation Office in Nabari City in addition to its Yokkaichi Bus Operation Office. Solar power generation facilities with a total output of about 1.6MW will be adopted at these three locations.

There have been no solar-panel-embedded roofs at any parking spaces of Mie Kotsu thus far. What triggered the adoption of such roofs was an inquiry from group company Sanko Real Estate Co Ltd. Sanko Real Estate has proactively developed solar power generation facilities, operating solar power plants with a total output of roughly 60MW at 21 locations in Mie Prefecture.

Considering making the best use of idle land owned by the group companies for solar power generation, Sanko Real Estate was seeking information on candidate sites from group companies.

Mie Kotsu did not have any land that could be offered as a candidate site. However, the company had many buildings and large spaces on the roofs at its branch operations. Starting from this inquiry, Mie Kotsu started considering commercializing solar power generation based on the feed-in tariff (FIT) scheme utilizing areas such as building roofs. Due to the load resistance of roofs and other restrictions, however, the company gave up on commercialization.

Amid such circumstances, JFE Technos Corp (Tsurumi-ku, Yokohama City), a wholly owned subsidiary of JFE Engineering Corp (Chiyoda-ku, Tokyo), proposed to Mie Kotsu the setting up of solar-panel-embedded roofs on its parking spaces for large buses. This company later came to provide engineering, procurement, and construction (EPC) services at the three locations.

Mie Kotsu had originally considered the benefits of roofing its parking spaces for large buses from a perspective of bus operation. It was primarily because roofing would improve bus inspection and maintenance efficiencies while helping the company reduce energy consumption for air conditioning inside buses (Fig. 2).

Fig. 2: Mie Kotsu considered the benefits of roofing parking spaces for large buses from a perspective of bus operation. It would contribute to improving bus inspection and maintenance efficiencies and cutting fuel cost for air conditioning inside buses. Every day, bus drivers make sure there are no problems with their buses before departing from parking spaces at each operation. When the weather is bad, for example, in the rain, the inspection environment deteriorates, and the physical load on drivers would increase.

In addition, when it snows or there is a frost, drivers would only start their buses after removing snow and frost from the front and side windows.

Should a roof be provided with a parking space, such an inspection environment under bad weather conditions would improve, and the load on bus drivers could be decreased as a result of less snow and frost removal work.

When the temperature is high during the summer, drivers start air conditioning in the buses before they start letting the passengers get on. If a roof is provided with a parking space, the temperature inside the buses can be kept from rising, resulting in a reduction in power consumption for air conditioning and saving fuel. Moreover, the roof could protect the buses from dust, wind and rain while they are parked, which could lead to reduced washing and protection of body paint.

Despite these many benefits, it costs a lot to build a new roof on a parking space for large buses. JFE Technos' proposal could solve this problem. That is to say, the cost for building a new roof could be recovered by selling power generated by solar panels embedded in the roof using the FIT scheme.

For Mie Kotsu, this became a business model that could eliminate the barrier of cost bearing by combining roof construction on a parking space, which is highly beneficial for its bus business, and the solar power generation business.