Welcome to our BE Solar FlexScore! With this score, we want to share insight on different curtailment approaches that can be used and their respective value. Enterprises often either don’t curtail — at least not voluntarily (see previous blog post), or only curtail reactively on the day itself when day-ahead prices are known (settled to be negative). But is this really the smartest move? Let’s find out.
For the live index, take a look here: https://www.companion.energy/be-solar-flexscore
We see three approaches to producing solar energy
We modeled and compared the potential value across three different curtailment approaches:
- Naive Production: Companies only exposed to day-ahead prices, producing solar energy regardless of the price.
- Basic Curtailment: Companies only exposed to day-ahead prices, curtailing reactively when the day-ahead price is negative.
- Advanced Curtailment: Companies exposed to both day-ahead and imbalance prices, using an end-to-end curtailment strategy: nominating curtailment in the day-ahead market when prices are negative, and curtailing/uncurtailing during the day based on imbalance market prices.
The value of each scenario is calculated ex post, using Elia-reported measured load factors, EPEX Spot Belgian day-ahead prices and Elia-reported quarterly imbalance prices. This means that the calculated values represents a theoretical maximum. We will publish our full calculation methodology soon.
How to compare the value of each approach?
To compare the value of the three approaches we defined some KPIs:
- Average Market Price (€/MWh): Average BE day-ahead price of the selected period (incl. non-sunny hours)
- Naive Production (€/MWh): Average BE day-ahead price during periods of solar generation when producing solar energy regardless of the price
- Basic Curtailment (€/MWh): Average BE day-ahead price during periods of solar generation when using basic curtailment.
- Advanced Curtailment (€/MWh): Average BE price (incl. day-ahead and imbalance price) during periods of solar generation, when using advanced curtailment
- BE Solar FlexScore (€/MWh): the additional value that could have been unlocked by using Advanced Curtailment vs. Basic Curtailment
When changing the units to €/MWp, the cumulative value over the selected period is displayed.
As mentioned earlier, the BE Solar FlexScore represents a theoretical maximum, since real-life deployment would require to rely on market price forecasts to decide when to curtail or uncurtail.
Some example insights
Let’s analyse some outcomes! The chart displays the cumulative solar value for the three defined approaches in May 2025. First, you see that Advanced Curtailment approach generates more than double the value vs. the Naive Production value. The cumulative BE Solar FlexScore is €5.93K/MWp, meaning that you could have earned maximum €5.93K/MWp if you steered your solar asset based on advanced curtailment.
Secondly, on May 11th, you see a drop in the value of Naive Production. This was caused by the record-low negative day-ahead prices in Belgium during sunny hours (avg. day-ahead price was -127.6 €/MWh, minimum -462.3 €/MWh). If you would have used Advanced Curtailment you could have generated 313.83 €/MWp additionally vs. Naive Production.
What are your take-aways? Share them with us, and with your network!
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The Curtailment Club
This blog is part of our series called “The Curtailment Club”, where we will dive into the drivers, misconceptions, and solutions behind renewable energy curtailment over the coming months.
