Photo/IllutrationThe Asahi Shimbun

  • Photo/Illustraion

The Consumer Affairs Agency is warning homeowners about the risk of fires spreading from solar cell modules placed on roofs without the use of noncombustible materials.

The agency’s Consumer Safety Investigation Commission said in a report released on Jan. 28 that 127 problems, including fires, occurred over a 10-year period until November 2017 involving solar cell modules installed on private homes.

In at least seven cases, the roof itself was burned. Those cases all involved solar cell modules placed directly on the roof without noncombustible materials as a buffer.

About 110,000 homes in Japan have solar cell modules without the noncombustible materials.

The agency is urging consumers with such types of solar panel installations to be extra cautious and suggested regular inspections of the systems.

In one case, a 43-year-old man in Saitama Prefecture was washing his car beside his home in March 2018 and did not notice that the roof was on fire.

A neighbor called the fire department after a passing motorist spotted the fire. When the man went up to the second floor, one of the bedrooms was filled with smoke.

He had installed solar cell modules directly on the roof in 2010.

After the fire spread from that setup, the man switched to solar cell modules that use mounts on the roof.

The 127 cases uncovered by the Consumer Safety Investigation Commission were found in the agency’s data bank, and they involved fires, smoke and overheating of the modules.

The commission more closely studied 72 cases after excluding incidents that had been investigated by other government agencies.

Thirteen cases involved fires breaking out from a module or the cable connected to the modules. The fires spread to the roof in seven of those incidents.

Those cases likely stemmed from problems in the wiring caused by deterioration or faulty manufacturing. The fires were probably sparked by an excess power load on a different circuit to which electricity flowed, according to the panel.

The commission’s report said about 2.4 million homes had solar cell modules installed as of October 2018.

The commission called on the industry minister to ask manufacturers of solar cell modules that do not have noncombustible materials to take measures to prevent fires.

“Owners should conduct regular inspections to ensure safe use,” said Kazuhiko Kato, a chief senior researcher at the National Institute of Advanced Industrial Science and Technology (AIST) who is knowledgeable about solar energy. “It will be important to spread awareness that steps should be taken to ensure safety by having manufacturers, the government and consumers gradually assume more responsibility.”

Solar cell modules increased in popularity after the start in 2012 of the “feed-in tariff” (FIT) system to promote renewable energy sources.

Although that system requires even homeowners to regularly inspect their solar cell power generating equipment, a survey by the Consumer Safety Investigation Commission found that about 70 percent of users did not conduct such checks.

In 2011, the PV Owner Network, Japan (PV-Net), a nonprofit organization that promotes the safe expansion of solar power generation, conducted a study of member homes along with the AIST.

The study found that about 30 percent of the 483 home solar energy generating systems surveyed had malfunctions requiring part replacement or repairs.

About 90 percent of those malfunctions occurred within 10 years after the solar panels were installed.

Ken Tsuzuku of PV-Net said that with more solar power systems now in use for more than 10 years, greater efforts are needed to ensure safe use of those systems.