August 25, 2026

Day-Ahead and Imbalance: How Covolt Generates Returns Twice with Flex Trading Pro

Olivier Maurissen

Published by

Olivier Maurissen

Covolt Belgium

Many companies believe that trading on the day-ahead market
and trading on the imbalance market are two separate worlds: you choose one market or the other.

At Covolt, things work differently. We take a position in the day-ahead market in advance, and decide at the last minute—based on the imbalance price—whether we’ll actually execute that position. A perfect example of a value stack.

Covolt manages more than 900 facilities in the Netherlands and Belgium and makes an estimated 9 million operational decisions every day, including real-time trade-offs like this between day-ahead and imbalance.

The classic scenario: Trading in a single market.

Trading? Simply put: It’s about buying low and selling high. The profit lies in the spread (the difference) between the kWhs charged and the kWhs discharged.

Many batteries operate on a fixed model. You either trade on the day-ahead market or on the imbalance market.

How Covolt Leverages Both Markets Simultaneously

We take a position in advance on the day-ahead market: a nomination to charge or discharge a battery at the day-ahead price for that quarter-hour. The difference lies in what happens during that quarter-hour itself. As soon as we see the current imbalance price, we reassess that nomination. Does charging as planned still make the most financial sense? If so, we simply carry out the nomination. Does the imbalance price at that moment look much more attractive? If so, we deviate from the nomination and switch the battery to the other direction.

A concrete example

On July 30, 26, between 3:00 p.m. and 4:00 p.m.: On the day-ahead market, we had nominated a purchase of 450 kW for this hour: we planned to charge the battery, so we intended to purchase electricity at the day-ahead price of €51/MWh.

During that hour, there was a sharp imbalance spike of €850/MWh. At that moment, it was much more advantageous for us to discharge rather than charge as planned. That’s why the battery switched modes: We’re discharging the battery at 1,570 kW!

Financially, this offers a twofold benefit:

  1. The 450 kW capacity commitment itself is not being met. We are not loading as agreed. That shortfall is billed at the imbalance price (€850) instead of the day-ahead price (€51).
  2. The additional 1,570 kW that we actually discharge is also billed at that €850 imbalance price.

Twice at the register

Instead of paying to charge (450 kW × €51), we get paid for not charging and for discharging, both at the much higher imbalance price of €850. That’s the effect of trading simultaneously on both markets. You don’t take on any extra risk by still taking a day-ahead position, because that position remains the baseline plan. But as soon as the imbalance market consistently yields higher returns, we adjust that plan. Two markets, one decision point, and two opportunities for a return. That’s Flex Trading Pro !

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