October 26, 2026
Curtailment for Commercial Solar Installations in Flanders: What Will Change in 2027?
Do you have a commercial solar installation in Flanders? If so, the rules will change as of January 1, 2027. A change in the regulations governing green energy certificates (GSCs) will have a direct impact on your installation’s output—unless you can actively manage its production.
In this article, we explain what curtailment is, why it is becoming increasingly relevant in Flanders, and how you can prepare your system for the new situation.
Published by
Olivier Maurissen
Covolt Belgium
What is curtailment?
Curtailment means that a solar power system temporarily reduces or completely halts electricity production. This can be done at the request of the grid operator (Elia or distribution system operator Fluvius), but it can also be a deliberate choice by the system owner—for example, to prevent electricity from being fed back into the grid at a time when the electricity price is negative.
When electricity prices are negative, you, as a producer, pay to feed your electricity into the grid. Feeding electricity back into the grid therefore costs money. Smart curtailment means that your system automatically detects this and adjusts production accordingly.
The GSC Rule Change Effective January 1, 2027
Green Energy Certificates are the financial incentive program for renewable energy production in Flanders. For every MWh your facility produces, you receive a GSC—but the rules are getting stricter.
GSCs are retained after 6+ consecutive hours
GSCs were not awarded only after six or more consecutive hours of negative prices. In practice, this threshold had little impact.
GSCs expire every 15 minutes when the price is negative
Every 15-minute period with a negative electricity price counts—even for local consumption. The six-hour threshold is being eliminated entirely.
Specifically: a 500-kWp system that generates 200 quarters per year at negative prices will lose GSC revenue on a structural basis under the new rule. That amounts to thousands of euros per year—year after year.
Why is this happening in Flanders right now?
Elia, the Belgian transmission system operator, published its first Flexibility Needs Assessment in August 2026. One striking finding: only 3% of measurable commercial solar installations in Belgium actively adjust their output in response to negative electricity prices. For onshore wind, that figure is 30%.
The difference isn't in the technology—it's a matter of active management. Most commercial solar installations run on autopilot and therefore lack the control needed to avoid losses due to negative prices.
Elia also expects solar power capacity in Belgium to grow significantly in the coming years: from the current capacity to 11 to 25 GW by 2035. More solar power means more frequent negative prices on a structural basis—and a growing risk for installations that are not actively managed.
How does Covolt Belgium handle this?
Covolt manages solar and battery capacity at more than 900 business locations in Belgium and the Netherlands via the Covolt Horizon platform. The system continuously monitors day-ahead and intraday electricity prices, grid congestion status, and the state of charge of any battery storage systems.
Is a negative price looming? If so, Covolt Horizon automatically adjusts production—by curtailing output or temporarily storing energy. Outside of those periods, your system operates at maximum capacity. The result: your GSC revenue remains intact, you never pay to feed power back into the grid, and you don’t have to do a thing.
Covolt operates independently of your inverter and energy provider and has a dedicated point of contact with expertise in Elia and Fluvius regulations. Want to learn more about asset monitoring for your installation?
When does this apply to you?
Active curtailment management is worthwhile if:
Covolt Belgium
Protect your GSC revenue for 2027.
Covolt will calculate, free of charge, how the regulatory change will affect your system—based on your location, connected capacity, and historical production profile.
Contact in Belgium
9 Filip Williotstraat,
, 2600 Berchem (Antwerp)
+32 3 377 49 33
sales-be@covolt.eu
