The primary revenue source for low-voltage grid-scale BESS is the frequency regulation market. Even if charging and discharging are never actually triggered, compensation (ΔkW value: standby compensation) is generated simply by being in a state of readiness — "on standby and available at any time." This page explains the revenue mechanism in detail, from the basics of the frequency regulation market through the regulatory reforms planned for FY2026.
Why Does a Battery Generate Revenue?
Electricity is a unique form of energy that must be consumed the instant it is generated, requiring a constant balance between generation and consumption. However, renewable energy sources such as solar and wind have variable output depending on weather conditions, making it increasingly difficult to maintain supply-demand balance in the power grid.
Even minor imbalances cause grid frequency fluctuations, raising the risk of equipment failures. Severe imbalances can lead to blackouts. For this reason, transmission system operators (TSOs) must always maintain a reserve capacity — known as "adjustment capability" — that can charge or discharge on short notice in emergencies.
The frequency regulation market is the mechanism through which this adjustment capability is procured, and BESS is recognized as the most suitable technology for this market.
Basic Structure of the Frequency Regulation Market
Two Types of Compensation
The frequency regulation market provides two types of compensation:
ΔkW Value (Standby Compensation) Compensation generated simply by being on standby as adjustment capability. Once a bid is awarded, payment is made regardless of whether actual charging or discharging is triggered. This is the primary revenue source for low-voltage grid-scale BESS.
kWh Value (Dispatch Compensation) Compensation paid based on the amount of electricity charged or discharged when dispatch is actually instructed. For primary frequency response (offline), kWh settlement is generally not conducted through the market; instead, imbalance settlement applies.
Primary Frequency Response (Offline) — The Market Segment for Low-Voltage BESS
The segment primarily targeted by low-voltage grid-scale BESS is primary frequency response (offline).
Key Characteristics
- Response time: Within 30 seconds
- Continuous duration: No fixed requirement
- Monitoring method: No real-time continuous monitoring (post-hoc data submission)
- No dedicated communication line (online connection) required
While standard grid-scale BESS requires a permanent communication line, primary frequency response (offline) allows participation through post-hoc data submission. This makes it accessible even for smaller battery systems — the ideal participation format for 49.9 kW low-voltage BESS.
Response to FY2026 Regulatory Reforms
Starting in FY2026, the frequency regulation market will transition to day-ahead trading. This reform shifts bidding from weekly/monthly cycles to a day-ahead basis, aligning procurement more closely with actual market conditions.
REVIX JAPAN's Readiness
Low-voltage grid-scale BESS provided by REVIX JAPAN features an EMS and operational framework compliant with post-FY2026 regulatory changes. Following the shift to day-ahead trading, operations will continue to focus on primary frequency response (offline) to secure standby compensation (subject to variation based on market prices and bid award rates).
Type A and Type B Bid Categories
The frequency regulation market includes Type A bids (for fully depreciated assets) and Type B bids (for assets not yet depreciated). Low-voltage grid-scale BESS can enter Type B bids for fixed-cost recovery in the early stages of deployment, enabling revenue planning that incorporates equipment cost recovery (subject to applicable regulations and conditions).
24-Hour Operation Schedule (Illustrative)
The following illustrates a typical 24-hour operation focused on primary frequency response (offline):
| Time Slot | Operation |
|---|---|
| 0:00–24:00 | Primarily operated under primary frequency response offline (day-ahead product, 30-minute blocks) |
| Selected blocks | Charging to maintain SOC (state of charge) |
The frequency regulation market is the primary focus because standby-compensation-based revenue is relatively predictable, and the burden of managing complex bid updates and SOC is comparatively low. The wholesale electricity market (arbitrage) is considered for supplementary use when price differentials are large or in curtailment areas.
Key Factors Affecting Revenue
Revenue varies based on the following factors. Please understand these in advance.
- Bid award rate: If the bid price exceeds the market price, the bid is not awarded and no compensation is generated.
- Uptime / Availability: No compensation is generated during periods of downtime due to failures or maintenance.
- Market price fluctuations: Frequency regulation market prices change based on regulatory reforms and competitive conditions.
- Price cap: Following the shift to day-ahead trading in FY2026, the price cap for primary and secondary① is scheduled to be revised from 19.51 yen to 15 yen/ΔkW per 30 minutes (further phased reductions are under consideration based on competitive conditions).
Summary: Key Characteristics of Low-Voltage Grid-Scale BESS Revenue
Revenue from low-voltage grid-scale BESS represents "compensation earned by contributing to power grid stability." A key feature is that the standby compensation mechanism generates income even without selling electricity. However, as a market-participatory model, revenue is not guaranteed and depends on market prices, bid award rates, and uptime.
REVIX JAPAN provides detailed revenue projections upon request. Please start with a materials request or inquiry.
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