Solar curtailment reaches Tokyo, Japan’s last holdout grid area
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Tepco Power Grid instructed renewable generators to reduce output on March 1, 2026, from 11:00 (JST) to 16:00, citing high solar generation, low weekend demand, and zero available inter-regional export capacity. It was the first time the utility had ever ordered economic curtailment.
“The onset of curtailment in the Tepco area is highly significant because it shows that even in Japan's largest power market – Tokyo, historically a net-importing load center – renewable deployment has begun to outpace system flexibility,” said Michiyo Miyamoto, energy finance specialist for Japan at the Institute for Energy Economics and Financial Analysis (IEEFA).
Output was cut by as much as 1.84 million kW at peak. Multiple Japanese-language outlets confirmed the event as Tepco's first-ever economic curtailment – distinct from a localized grid curtailment at the Boso substation in Chiba prefecture on Jan. 6, 2025, which affected only generators with non-firm grid connections.
Miyamoto said the most direct remedies are expanded battery storage, stronger inter-regional transmission, and improved market incentives.
