Japan Energy Storage Development Institute Opens 'Shichinoki Battery Storage' in Kamisato Town, Saitama Prefecture — Achieves Grid Connection in Approx. 3.5 Months, Enters Balancing Market Simultaneously with Kaminara Plant 2.5 Months Post-Energization

Japan Energy Storage Development Institute Co., Ltd. (Headquarters: Tokyo; Representative Director: Akira Hoshino; hereinafter "JESDI") announces the commencement of operations today, June 16, 2026, at the 'Shichinoki Battery Storage'—a grid-scale battery project developed in Kamisato Town, Saitama Prefecture.

The Shichinoki Battery Storage achieved grid connection on March 31, 2026, just approximately 3.5 months after groundbreaking (December 15, 2025)—a construction speed among the fastest in the industry. Furthermore, it entered the balancing market (primary frequency regulation) on the same day as the Kaminara Battery Storage (Kumagaya City, Saitama Prefecture), which began construction 14 days earlier, and just 2.5 months after grid connection. Following the previous announcement highlighting 'rapid grid connection in 3.5 months and adoption of 5ft compact systems,' this release demonstrates the implementation capability of the four-company alliance in simultaneously managing two projects to concurrent operation.

Installation Overview

- Facility Name: Shichinoki Battery Storage - Location: Kamisato Town, Kodama District, Saitama Prefecture - Output: 2MW - Groundbreaking Date: December 15, 2025 - Grid Connection Date: March 31, 2026 (approx. 3.5 months after groundbreaking—industry-leading speed) - Operation Start Date: June 16, 2026 (approx. 2.5 months after grid connection, approx. 6 months after groundbreaking) - Construction Partner: E-Top Co., Ltd. - Operations Support: RUTILEA Inc. - Energy Storage System: HOBE ENERGY Co., Ltd.'s 5ft compact integrated energy storage system (EMS, PCS, and substation equipment in unified design)

HOBE ENERGY's Integrated System — Adopted in Shichinoki Following Kaminara Demonstration

The Shichinoki Battery Storage also adopts HOBE ENERGY Co., Ltd.'s integrated energy storage system, the same as used at the Kaminara facility. The model, in which HOBE ENERGY designs and supplies all equipment—including batteries, EMS, PCS, and substation equipment—as an integrated package, was previously demonstrated at Kaminara. Shichinoki serves as a project to verify its reproducibility.

### Equipment Responsibilities

- Energy Storage System: 5ft compact LFP battery (HOBE ENERGY) - EMS: In-house energy management system (charge/discharge control, optimization) (HOBE ENERGY) - PCS: Power conditioner (AC/DC conversion) (HOBE ENERGY) - Substation Equipment: PCS and step-up transformer integrated substation container (HOBE ENERGY) - Integration & Commissioning: Inter-device connection, integration testing, and specification optimization based on site conditions (HOBE ENERGY)

Grid Connection in Approx. 3.5 Months — Background of Construction Speed

While similar grid-scale battery projects often take 5–6 months or more from groundbreaking to grid connection, Shichinoki achieved connection in just approximately 3.5 months after groundbreaking (December 15, 2025), completing energization on March 31, 2026. The key factors enabling this rapid construction are as follows:

- Ease of transport and installation of 5ft compact units: Compared to the industry-standard 20ft containers, the compact size allows access to sites with narrow access routes or sharp curves, significantly shortening installation time. - On-site efficiency through HOBE's integrated design: Since the battery, EMS, PCS, and substation equipment are all designed as a unified system, on-site interconnection and adjustment work are minimized. - High-precision construction management by E-Top: Achieved zero schedule delays while concurrently managing the Kaminara project, demonstrating capability in simultaneous multi-project execution.

Simultaneous Operation with Kaminara & Market Entry 2.5 Months Post-Connection — Proof of Parallel Project Management

The Shichinoki Battery Storage began operations on June 16, 2026—the same day as the Kaminara Battery Storage, despite starting construction 14 days later. Successfully managing two projects with different timelines—groundbreaking, grid connection, and operational schedules—and achieving concurrent operation demonstrates that the integrated four-company alliance (JESDI, HOBE ENERGY, RUTILEA, and E-Top) functions as a replicable launch model capable of handling multiple projects.

The entry into the balancing market just 2.5 months after grid connection (March 31, 2026) was supported by the following three structures established at the Kaminara facility:

### Three Factors Enabling Market Entry 2.5 Months Post-Connection (Replicated from Kaminara to Shichinoki)

- ① Commissioning of the HOBE system completed in just 4 days. Since HOBE ENERGY designed the battery, EMS, PCS, and substation equipment as an integrated system, inter-device specification adjustments were finalized during the design phase, enabling the same speed at Shichinoki as at Kaminara. - ② Market entry testing completed in 1 day through HOBE-RUTILEA collaboration. The equipment side (HOBE ENERGY) and market operations side (RUTILEA) shared requirements as a unified team from the early design phase, maintaining the same coordination even with two parallel projects. - ③ Efficient TSO coordination: Grid interconnection and market entry discussions with transmission system operators (TSOs) were advanced accurately by a team well-versed in entry requirements, minimizing procedural timelines.

Future Outlook — Establishing Multi-Project Capability and Nationwide Expansion

The achievement of grid connection in 3.5 months and simultaneous operation with Kaminara at Shichinoki demonstrates that the four-company alliance functions as a replicable model capable of managing multiple projects in parallel, not limited to single projects. JESDI is already advancing multiple upcoming projects—including the Hachigata and Orinokuchi Battery Storage facilities in Saitama Prefecture—using this model.

JESDI will continue strengthening the four-company alliance with HOBE ENERGY Co., Ltd. (integrated energy storage systems), RUTILEA Inc. (aggregator and market operations), and E-Top Co., Ltd. (construction), accelerating the deployment of energy storage infrastructure across Japan.

Inquiries

Japan Energy Storage Development Institute Co., Ltd. Contact Form: https://japan-energystorage.co.jp/contact/

Company Overview

- Company Name: Japan Energy Storage Development Institute Co., Ltd. - Established: October 2024 - Representative Director: Akira Hoshino - Address: 2-12-4-303 Kitaaoyama, Minato-ku, Tokyo 107-0061 - Capital: 10 million JPY - Tel: 03-6899-2733 - Business: Design, construction, operation, maintenance, management, technology development, sales of battery storage facilities, and power supply-related services - URL: https://japan-energystorage.co.jp

Partner Companies

- HOBE ENERGY Co., Ltd.: https://hobeenergy.co.jp/ - RUTILEA Inc.: https://www.rutilea.com/ - E-Top Co., Ltd.: https://etop-co.com/