After recent typhoons ravaged the nation's power grid and disrupted services to almost 1.4 million customers, the government is encouraging homeowners to invest in storage systems, seeking to marry batteries with existing rooftop solar capacity to create backup electricity networks.

The backbone would be the 2.3 million rooftop solar installations across the country that have been selling power to the grid for years under long-term contracts. As those deals begin to lapse, with the first batch expiring this month, policymakers in Tokyo see an opportunity to create networks more resistant to disruptions, which are expected to become more frequent due to climate change.

"We need to make our power system more resilient to natural disasters," said Takuya Yamazaki, a director of the new energy division at the Ministry of Economy, Trade and Industry. "Storms are becoming more powerful and the damage is getting more serious."