Generation Control Day-Ahead
In brief
Curtailing generation installations based on (negative) day-ahead hourly prices to limit the costs of electricity feed-in during these hours.
Locations with generation and a dynamic or day-ahead energy contract may have to pay for feed-in when the day-ahead market price is negative. To prevent or limit this, curtailment can be used.
Curtailment is the control and thereby (partial) reduction of generation output. This may be applied in response to negative prices, for example.
How it works
This control strategy continuously monitors the hourly price of the day-ahead market through a software connection with the EPEX market, and automatically (partially) curtails generation installations so that little or no electricity is fed back to the grid during these hours. The graph below shows this in a simplified form: generation increases throughout the day, and as soon as the price drops below zero in the afternoon, generation is also steered to zero.
Compensating for consumption
If there is also consumption on the same grid connection, it is generally advantageous during curtailment to still supply own consumption from the generation. This falls under consumption compensated curtailment. By continuously adjusting the generation output, it is kept equal to the consumption, and only the feed-in during negative prices is reduced to zero.
Compensating for consumption requires a connection to a meter on the main grid connection.
Offset price
It is possible to choose a custom amount from which curtailment is triggered. The system automatically retrieves the base price from the EPEX market; on top of the actual price, certain additional costs apply that affect when the price is truly negative.
The offset price is the variable surcharge on top of the base purchase price, including VAT, procurement fee, and energy tax charged by the energy supplier. This offset is added by us to the base EPEX market price, and if the total price is still negative, curtailment is applied and the PV installation is switched off.
Additional information
The Generation Control Day-Ahead strategy makes it possible to automatically curtail generation installations based on hourly prices from the day-ahead market. Below you will find further explanation of how specific situations can be configured and what technical prerequisites apply.
Partial curtailment
In many cases it is not desirable to fully curtail a generation installation during negative prices. For example, when the negative electricity price is not lower than the energy tax amount for consumption, it may be economically more advantageous to continue using the generated energy. In practice, it is rare for the EPEX price to be so negative that it directly becomes profitable to draw power from the grid. At connections with an SDE subsidy, it is also generally attractive to continue generating. This can be fine-tuned via an offset price. By setting the offset correctly, the price level at which the control strategy becomes active is determined.
When a readable kWh meter is present on the main grid connection, the system can continuously align the current consumption with the available generation. This limits only the feed-in during negative prices, while own consumption is supplied from renewable energy. If no kWh meter is yet present, additional installation costs and a brief interruption during placement should be taken into account.
Integration with an existing power control strategy
When an existing power-limiting control strategy is active on the generation installation, this is taken over in the Envi.Baseenvi.base De energiecontroller van Envitron die apparaten uitleest, aanstuurt en data opslaat achter de hoofdaansluiting. in the form of a Grid Guard. This prevents conflicts between different control strategies. If a power control strategy is not taken over, a situation may arise in which the existing control strategy and the day-ahead control work against each other. This can lead to instability in the control output. It is therefore essential that existing control strategies are correctly integrated into the Envi.Baseenvi.base De energiecontroller van Envitron die apparaten uitleest, aanstuurt en data opslaat achter de hoofdaansluiting. and removed from the original installation configuration.