The Japanese government is promoting solar power to achieve a carbon-free society. But that policy has hit a bump as some power utility companies are asking suppliers to suspend generation temporarily.

On sunny days, the supply of solar power can exceed demand. The aim of the suspensions is to prevent a massive blackout caused by a power surge in the worst-case scenario.

Suspending generation would make it difficult for solar-power suppliers to earn sufficient returns on their investment and expand their operations.

Until now, Kyushu Electric Power Company in southwestern Japan was the only utility in the country to make such requests. The Kyushu region has abundant sunshine and boasts high solar-power output. Earlier this month, however, power companies in three other regions requested suspensions for the first time.

The industry ministry plans to make more power lines available for transferring excess electricity to other areas. It also aims to promote the use of batteries to store electricity.