Japan Solar Update: No.196 (Apr 13 ~ 17, 2026)
Japan has reached nationwide curtailment with Tokyo’s first implementation. Efforts are underway to optimize control and reduce curtailment volumes.
<Key points>
- With the first implementation of renewable energy output curtailment in the Tokyo area, curtailment has now occurred across all ten grid areas in Japan
- In the Kyushu area, control and settlement categories for online proxy control will be divided into “Online Extra-High Voltage” and “Online High Voltage and Below”
- Aligning control instructions for extra-high voltage resources closer to real-time supply–demand balancing is expected to reduce overall curtailment volumes
Implementation of Output Curtailment in the Tokyo Area
Renewable energy output curtailment was implemented for the first time on March 1.
Output Curtailment Results（Preliminary）
| Renewable Energy Output Curtailment Period | March 1 (Sun), 2026 11:00 ~ 16:00 |
| Time of Peak Demand | 12:00 ~ 12:30 |
| Volume of Renewable Energy Output Curtailment | 1.84 GW |
Additional Measures to Reduce Curtailment Volume in the Kyushu Area
Output control instructions for online power sources
- For extra-high voltage power sources, issuing control instructions 10–30 minutes before real-time supply-demand balancing is technically feasible
- For high voltage and below, additional time is required to obtain control schedules via power conditioners (PCS), so operations assume issuing instructions approximately 1–2 hours in advance
Proposed Measures for Further Curtailment Reduction
By separating control categories into “Online Extra-High Voltage” and “Online High Voltage and Below”, it becomes possible to delay control instructions for online extra-high voltage until just before real-time balancing, thereby reducing curtailment volume
From the perspective of ensuring fairness in settlement for online proxy control, it is also necessary to revise categories settlement accordingly
In the Kyushu area—where online integration has steadily progressed—this initiative will be implemented as soon as preparations are complete. Accordingly, both: control categories, and settlement categories for online proxy control will be divided into the two segments above
For other areas, general transmission and distribution operators will consider introducing these measures based on the progress of online integration, and the status of output curtailment implementation in each area.
Figure 1. Overview of Discussions Related to Renewable Energy Output Curtailment
Source: Compiled by RTS Corporation based on materials from the 8th Next-Generation Power Grid Working Group (March 16, 2026)