Previous post “Steady the solar profile” demonstrated how intermittent solar production could be flatten towards a stable and predictable injection.
This enables solar power to offer ancillary services downward volume to balance the grid during peak hours of grid overload. Indeed ancillary services requires the energy source to be foreseeable and steady, which is why solar power has historically been consider unfit for it.
Well, this is worth addressing for at least 2 reasons. One ancillary services are often activated on carbon intensive sources like gas or other fossil fuels. Two, ancillary services can be a significant source of revenues for solar power plants.
Power control output
Power control on a 1 MWp solar power plant based in Paris, Epon Energy
The green bars represent a steady and foreseeable output. From there we submitted downward activations volumes to the grid. When not activated, the solar power plant values its injections on the spot with no power control. When activated it switches to power control mode to deliver engaged volumes.
This strategy has been very profitable in Belgium. Combining spot revenues with downward activations reached profitability above 100€/MWh in 2024.
Ancillary services market is however expected to contract in the next years with the increase of battery storage capacity. Further since November 2024, Belgium joined the European aggregation of ancillary services (PICASSO), which also contracted the market for Belgium players.
Spot injections and aFRR downward activations revenues split
Spot and aFRR downward activations flexible strategy for a 1 MWp solar power plant based in Brussels, Epon Energy
This strategy also raises the question of a smarter but decreased production of solar power plants. Indeed aFRR downward activations result in a diminution of total solar production. The following table describes effective productions and revenues for the solar power plant for such a strategy.
Strategies comparison
| Strategy | Full spot injections | Spot and aFRR downward activations |
| Total yearly production | 853,01 MWh | 373,67 MWh |
| Total yearly revenues | 32.436 € | 94.835 € |
Epon Energy