Since then, we at Entelios have prequalified four plants with a combined capacity of 175 MWp. What started as a lighthouse project has now become a growing portfolio.
The key question is no longer whether PV can fundamentally participate in the aFRR market. The first months of live operation have shown that it can. The more interesting question is now the next one: under what conditions does marketing become economically attractive and operationally robust?
Why PV in aFRR is more than a symbolic project
For a long time, photovoltaics was not considered a typical asset class for balancing reserves. Too volatile, too dependent on forecasts, too heavily driven by weather conditions. That is precisely why the successful prequalification for the aFRR market is such an important step. It shows that renewable generation assets can do more than just supply electricity. Under the right technical and operational conditions, they can also provide ancillary services.
In practice, however, successful commercialization is not determined by a single milestone, but by day-to-day operations. This is where it becomes clear how closely technical constraints, weather forecasts, market prices and energy market logic are intertwined.
What the trading decision actually depends on
In operational trading, our decisions are essentially based on two key variables: reliably marketable capacity and price forecasts.
For PV, reliably marketable capacity is naturally not identical to installed capacity. It depends on how robustly and conservatively the expected feed-in can be assessed for a given time window. In other words, what matters is not the theoretically possible PV generation, but the share of it that can be marketed in the balancing reserve market with sufficient confidence.
The second factor is the price forecast for the relevant markets. Only the interaction of these two variables results in a sound marketing decision. This is exactly where the difference becomes clear between a purely technical proof of concept and an economically viable operating strategy.
First practical insight: Negative aFRR is particularly attractive during sunny hours
One of the most important insights from the first few months is this: prices for negative balancing capacity typically increase during particularly sunny hours.
Second practical insight: Cross-market optimization remains challenging
A second insight is at least as important: the risk of negative energy prices influences cross-market optimization and creates significant opportunities.
For PV plants, it is therefore not enough to look only at the single market that appears most attractive in the short term. In practice, it can make more economic sense to curtail a plant in a controlled manner and offer positive balancing capacity if, at the same time, the risk of negative electricity prices in the power market is increasing or is already clearly foreseeable.
This is exactly where the complexity of the market cascade becomes apparent. The interactions between the balancing capacity market and the power market make optimization challenging. What may look like a simple opportunity at first glance is, in reality, a complex, algorithm-based and continuous optimization process.
Third practical insight: Individual plants quickly reach their limits
Our initial operating experience also shows that individual plants can currently only be marketed to a limited extent. This is mainly due to the necessary safety margins applied to reliably marketable capacity. Forecast risks, technical boundary conditions and conservative operating parameters significantly limit the economically usable share of capacity for individual PV parks.
