Battery-equipped PV System Utilized at Time of Power Failure

2019/11/14 13:49
Sousuke Kudou, technical writer
Kyonan Elementary School, where the PV system equipped with storage batteries was installed (source: Smart Solar)
The PV system set up on the roof (source: Smart Solar)
The storage battery system installed inside the school (source: Smart Solar)

At the time of the large-scale power failure caused by Typhoon No 15, which hit Japan Sept 9, 2019, a self-consumption-type solar power generation (PV) system equipped with storage batteries set up at Kyonan Elementary School in Kyonan-machi (town), Chiba Prefecture, was utilized as an emergency power source.

The PV system was installed by Smart Solar Corp (Chuo-ku, Tokyo) for the School New Deal Program of Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT).

The system stores electricity generated with solar panels in the storage batteries. This time, direct-current (DC) power stored in the batteries was converted into alternating-current (AC) power by using an inverter for supplying electricity for consumption in the school.

In April 2010, 20kW of solar panels and a storage battery with a capacity of 16kW and an output of 22kW were installed, and the system was also utilized at the time of the Great East Japan Earthquake. Based on the lessons learned from the disaster, 10kW of solar panels and a storage battery with a capacity of 16kW and an output of 10kW were added in October 2013.

Due to Typhoon No 15, about 930,000 houses were blacked out in the service area of Tokyo Electric Power Company Holdings Inc (TEPCO). An O&M (operation and maintenance) team of Smart Solar visited the area Sept 10, 2019, and confirmed that power was unavailable in the area surrounding the elementary school. Also, flying broken tiles cracked two solar panels, and they were replaced.

The inside of the school was very dangerous because, for example, glass objects were broken and corridors were flooded. However, electricity was available because of the PV system, and it was possible to remove glass pieces scattered in classrooms and corridors by using vacuum cleaners, Kyonan Elementary School Principal Higuchi said.

In addition, in Nagano City, which was afflicted by Typhoon No 19 (which hit Japan Oct 12, 2019), PD Japan (local company) lent an uninterruptible power supply (UPS) system to local shelters that lost power, for free, contributing to restoration activities including information collection.

Specifically, PD Japan provided a 100W model of the "MSD-Box" supporting anti-disaster measures. It is a hybrid power supply system that can also be used in normal times, using both commercial power and solar electricity. In the case of a power outage, it stores solar electricity by using an independent circuit and supplies electricity from its storage battery during nighttime hours.

In the case of Typhoon No 19, banks collapsed over 70m in Hoyasu District in the morning of Oct 13, 2019, flooding an area that stretches over about 5km in the north-south direction and 2km in the east-west direction, with the estimated maximum flood depth of 4.3m.

Mud water also flowed into Toyono Branch Office of Nagano City, which is located about 3.5km away from the collapse point and used as a shelter in Toyono District. And a high-voltage power-receiving unit that relays electricity generated with an emergency generator to other buildings sank under water. As a result, the office lost power.