Battery-Driven Bidding Strategies in the Continuous Intraday Market

Trading · 10 September, 2025 · 10 Min Read

Brief on the Continuous Intraday Market (CID)

Principle

The Continuous Intraday Market allows market participants to trade electricity closer to real-time, enabling them to adjust their positions based on updated forecasts for generation and consumption. This flexibility is crucial for balancing the grid and integrating intermittent renewable energy sources.

Order book

The CID operates on an explicit order book system, similar to financial markets. Buyers submit bids (orders to buy at a certain price), and sellers submit asks (orders to sell at a certain price). When a bid and an offer match, a trade occurs. This continuous matching allows for constant price discovery and immediate execution of trades.

An order book for a given product (e.g. from 13:00 to 14:00) contains a list of available offers for buying or selling a volume of energy at a specific price. Below is an example.

Trade example

Imagine a seller offers 10 MW at 75.00 €/MWh. A buyer then places a bid for 8 MWh at 77.10 €/MWh. Since the buyer’s bid price is higher than the seller’s offer price, a trade will immediately occur. The settlement price is the price of the first order that was placed, here it is the seller price at 75.00€/MWh and for 8 MWh. The remaining 2 MWh from the seller’s offer will stay in the order book, waiting for another buyer. This example is simplified, for a complete understanding of trading on the CID, please consult the full description

Participants

Buyers and sellers work together across Europe as long as the border transmission lines are not congested, meaning that the orders that appear on the order book are common to many different bidding zones.

Above is a map of the participating countries to the continuous intraday trading market, named Single Intraday Coupling (SIDC) system. It is available on the ENTSOE webiste

Timeline

In France, the local market opens at D-1, 15:00. Cross-border orders are available at D-1, 22:00 and can be traded up to 60 minutes prior to delivery. Local orders can be traded up to 5min prior to delivery.

Liquidity

The volumes traded on the EPEX SPOT power markets increase by about +22% each year. Most of the trades occur in Germany, then the Netherlands, then France. Detailed insight are available on the Epex Spot website .

The volume traded on the day-ahead market in 2024 was 654 TWh, meaning that the CID represents about 25% of the energy traded on the power markets.

Battery Benefits

There are many ways to trade a battery’s capacity on the intraday market. This article focuses on methods that do not allow trading on the imbalance. In other words, the battery is always covering the positions taken on the CID.

The general case is when the battery already covers positions, either because it traded energy on the day-ahead market, or because it already traded on the intraday. From that point, it can increase the existing profit in two ways that can combine :

Increasing revenus by buying low and selling high
Lowering the tax costs by cancelling existing positions or shifting the cycling to lower tax hours

These possibilities, combined with frequent change in the order book, allow for many trades in a day as can be seen in the illustration below.

The purple dashed line represents the time at which the trades are made, it is a simulated “current time”. The black line is the initial position and the red dashed line is the final position. It changes as the trading time moves forward, which means that a high amount of the energy is netted. Netted energy accounts for a position that is created and then canceled prior to physical delivery : there is a financial settlement but no physical delivery.

The operations are divided into two categories : maintaining the number of cycles or modifying it.

Constant cycling

There is no change in the sum of scheduled power, but there is a shift in the dates at which it occurs.

In the above image, the previous position is in blue, most of the time it is hidden behind the current position in red. The operation shifts the previous position from 21:00 to 19:00. The shift is displayed by the green line.

Modified cycling

There is a modification in the sum of scheduled power, that can increase or decrease the total cycles.

In the above image there is scheduled power that is added at 13:00 (additional discharge) and at 16:00 (additional charge), increasing the total cycles. Note that these positions can be cancelled in a later time depending on market opportunities.

Performances

A battery’s additional profit is determined by several key factors, including its existing schedule in day-ahead and ancillary service markets, the liquidity of the continuous intraday (CID) market, battery size, and optimizer performance. The proprietary algorithms developed at StackEase are engineered to process all these variables, delivering exceptional performance with a rapid optimization speed of approximately 50ms.

How to participate in the CID market ?

StackEase operates batteries in real-time. We provide performance monitoring services by simulating your battery. Results are available 24/7 on a live dashboard.

We also provide aggregation services by including your current, or future, batteries in our balancing perimeter. Allowing your company to get direct benefits from the CID, but also from ancillary services, arbitrage on supply contract for BTM and tax optimization via our efficient unified cross-market algorithms solution.

Please contact sales@stackease.ai to know more.