Understanding Day-ahead & Intraday Markets

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Why is electricity traded on a daily basis?

To ensure that supply and demand are balanced in real-time and that the electricity grid remains stable and reliable. 

Electricity cannot be easily stored in large quantities, so it must be generated in real-time to match the constantly changing demand for electricity. 

This means that the electricity market operates in a continuous cycle of production, delivery, and consumption. Short-term markets — particularly the day-ahead and intraday markets — are the primary mechanisms through which this balance is achieved, allowing generators and consumers to adjust their positions as conditions evolve.

Example of the day-ahead and intraday dynamics

The main difference between the two markets is the time horizon for trading

The day-ahead market allows market participants to buy and sell electricity for the next day, while the intraday market allows for trading within the same day.

Day-ahead vs. Intraday Market — Comparison

Day-ahead market

In the day-ahead market, participants submit their bids and offers for electricity to be produced and delivered the next day. It is the most liquid short-term electricity market in Europe and sets the reference price used across the industry — including for PPA capture price calculations.

• These bids and offers take place on the spot market of a respective power exchange (such as EPEX SPOT and NORDPOOL).
• Are then matched by a market operator to determine the market clearing price, which is the price at which all accepted bids and offers can be fulfilled.
• The tradings can also occur outside of power exchanges through OTC (over the counter) contracts between two parties.

In Europe, day-ahead markets are coupled across borders through the Single Day-Ahead Coupling (SDAC) mechanism, which allows electricity to flow between countries based on price differences, improving overall market efficiency. Prices are set hourly — or in 15-minute intervals in markets that have adopted higher resolution — and can vary significantly depending on renewable generation, demand, and cross-border flows.

Intraday market

In contrast, the intraday market allows for trading within the same day. It opens after day-ahead results are published and closes shortly before the delivery period begins — typically 30 to 60 minutes before delivery, depending on the country and market rules.

• This market is used to adjust for any unexpected changes in demand or supply that may arise during the day.
• Market participants can buy or sell electricity in the intraday market to meet their immediate energy needs, or to make up for any imbalances that may have occurred in the day-ahead market.
• Day trading power assets based on demand helps fulfill contract commitments, reduce imbalance costs, maximize profits, and increase system stability.

The intraday market is particularly important for renewable energy generators, whose output depends on weather conditions that are difficult to forecast precisely 24 hours in advance. A wind farm that forecasted 50 MW for a given hour may only produce 35 MW — the intraday market allows the generator to buy back the shortfall and avoid costly imbalance settlement. Across Europe, intraday markets are increasingly interconnected through the XBID (Cross-Border Intraday) platform, enabling continuous cross-border trading.

Interesting facts about spot market trading 

• For both day-ahead and intraday markets, the minimum tradable amount is 0.1 MW.
• 1 MWh can range from -9,999 to 9,999 euros. 
• In both markets, bidders are anonymous and trading happens on every day of the year. 
• Electricity produced through both traditional and renewable methods is considered equal and is exchanged without any proof of origin certificates.

Source: Next Kraftwerke

Frequently Asked Questions

What is the day-ahead electricity market?

The day-ahead market is where electricity is bought and sold for delivery the following day. Participants submit bids and offers before noon (12:00 CET), and a market operator matches them to determine an hourly clearing price for each delivery period of the next day.

What is the intraday electricity market?

The intraday market allows electricity to be traded on the same day as delivery, up to 30–60 minutes before the delivery period begins. It is primarily used to correct imbalances caused by forecast errors — for example, when a solar farm produces less than expected due to cloud cover.

What is the difference between day-ahead and intraday markets?

The key difference is timing. The day-ahead market closes the day before delivery and uses a uniform auction price. The intraday market operates continuously on the day of delivery using bilateral, pay-as-bid matching. Day-ahead is used for planning; intraday is used for real-time adjustments.

Who participates in day-ahead and intraday markets?

Generators, electricity retailers, large industrial consumers, and balancing responsible parties (BRPs) all participate. Renewable energy producers are particularly active in the intraday market, as their output is harder to forecast and often needs to be adjusted close to delivery.

How do day-ahead and intraday markets affect PPA pricing?

PPA prices are closely linked to day-ahead market prices, as most renewable generators sell their output on the day-ahead market. Capture prices — the average price a generator actually receives — are directly influenced by day-ahead price patterns. Intraday market conditions affect imbalance costs, which in turn impact the net revenue a generator earns under a PPA.

About Synertics

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