EPRX: Supply-Demand Adjustment Market Transaction Fees to Double in FY2026! Practical Points Explained for BESS Operators.

BESS NEWS, a specialized news site that provides important information on grid-scale battery storage systems (BESS) for free, has recently published an explanatory article for BESS operators, aggregators, and investment practitioners regarding the revision of transaction fees in the supply-demand adjustment market for FY2026, announced by EPRX (Electricity Supply-Demand Adjustment Capacity Exchange). The article is titled "EPRX: Supply-Demand Adjustment Market Transaction Fees to Double ~FY2026 at 0.06 yen/ΔkW・30 minutes, effective from April 1 for actual supply-demand~".

On February 13, 2026, EPRX announced that the transaction fee unit price in the supply-demand adjustment market for FY2026 would change from 0.03 yen/ΔkW・30 minutes (excluding tax) in FY2025 to 0.06 yen/ΔkW・30 minutes (excluding tax). At first glance, the unit price has doubled, which is a change that participants in the supply-demand adjustment market should confirm in their revenue estimations and contract practices.

What BESS NEWS particularly focused on this time was not just the superficial story of "fees doubling," but rather the points that BESS operators tend to overlook in practice. Specifically, it clarifies that the application criterion is the actual supply-demand date, not the bidding date; that 0.06 yen is neither a kWh unit price nor an annual unit price; and that while mid-year revisions are possible, they have not been decided at this time.

BESS NEWS explains this revision not merely as a change in market fees, but as a practical theme that BESS operators participating in the supply-demand adjustment market should review in their revenue models, aggregator contracts, and settlement confirmations.

Table of Contents

Themes explained by BESS NEWS this time 1-1. EPRX decides transaction fee unit price for FY2026 1-2. BESS operators should look beyond just the "unit price"

Three key points to grasp from this revision 2-1. Transaction fee unit price to 0.06 yen/ΔkW・30 minutes 2-2. Application criterion is the actual supply-demand date, not the bidding date 2-3. The background to the fee increase is an increase in system-related costs

Practical considerations often overlooked 3-1. 0.06 yen is neither a kWh unit price nor an annual unit price 3-2. New unit price applies even if bid on March 31, if actual supply-demand is April 1 3-3. Mid-year revision is a possibility, not a decided implementation

1. Themes explained by BESS NEWS this time

In this BESS NEWS article, in response to EPRX's decision to set the transaction fee unit price in the supply-demand adjustment market for FY2026 at 0.06 yen/ΔkW・30 minutes (excluding tax), it organizes how BESS operators should interpret primary information. The supply-demand adjustment market is a market for trading "adjustment capacity" to balance electricity supply and demand. BESS is attracting attention as a resource that can provide adjustment capacity through charging and discharging. However, this article does not merely explain the market system itself. BESS NEWS focuses on explaining what BESS operators should actually confirm: "unit of price," "effective date," "contractual fee burden," and "possibility of mid-year revision."

2. Three key points to grasp from this revision

First, the transaction fee unit price for FY2026 will change from 0.03 yen/ΔkW・30 minutes (excluding tax) in FY2025 to 0.06 yen/ΔkW・30 minutes (excluding tax).

Next important point is the timing of application. The new unit price will apply from April 1, 2026, for actual supply-demand. The actual supply-demand date here refers to the day when electricity is actually delivered or adjustment capacity is provided.

This means that even if a bid is made on March 31, the new unit price will apply if the actual supply-demand date is April 1. In the main BESS NEWS article, this point of "looking at the actual supply-demand date, not the bidding date" is organized as a particularly important consideration for practical work spanning fiscal years.

Furthermore, as a background to the fee increase, EPRX documents indicate an anticipated increase in system-related costs from 2.69 billion yen to 6.63 billion yen. System modifications and maintenance costs associated with changes in the supply-demand adjustment market system and operations are largely related to this unit price revision.

3. Practical considerations often overlooked

A common misunderstanding with this change is the unit of 0.06 yen/ΔkW・30 minutes.

"0.06 yen" alone may seem like a small amount. However, this is not a unit price per kWh, nor is it an annual unit price per 1kW. It is strictly a transaction fee unit price when looking at ΔkW contracted volume in 30-minute increments.

Therefore, when BESS operators conduct revenue simulations, it is crucial not to confuse kW, kWh, ΔkW, and 30-minute blocks. Misinterpreting the units can lead to significant discrepancies in annual cost estimates.

Another point to note is the handling of mid-year revisions. EPRX explains that if the market operator determines that certain conditions are met, transaction fees may be revised mid-year. However, this