Revenue Streams in Detail

FCR is the primary control reserve of the European interconnected grid. BESS provide symmetric power that is automatically activated on frequency deviations — without an external activation command. Remuneration is paid as a capacity fee per MW reserved.

aFRR restores frequency after FCR activation. BESS bid positive and negative reserve capacity in 15-minute products. Remuneration consists of an availability payment (regardless of activation) plus an activation payment.

The intraday market enables continuous trading until shortly before the delivery hour. BESS use it to arbitrage short-term price movements — especially in hours with high RE feed-in. Combined with aFRR reservation, intraday significantly increases asset utilisation.

The day-ahead auction sets hourly prices for the following day. BESS exploit the price difference between cheap off-peak hours (charging) and expensive peak hours (discharging). As a standalone revenue source often too volatile — as a stack complement alongside ancillary services it is effective.

Under the market premium model, a direct marketer (Direktvermarkter) sells the electricity on the spot market (day-ahead & intraday) on behalf of the operator. The government tops up this market revenue with a market premium. For co-located BESS, direct marketing creates optimisation potential by coordinating feed-in and storage.

The fixed feed-in tariff under EEG applies to installations below the direct marketing threshold. It provides price certainty but no revenue optimisation. For utility-scale BESS projects it is generally not relevant — but applicable for smaller co-located assets.

Green storage assets (Grünstromspeicher) under EEG charge exclusively from co-located RE generation. This constraint reduces dispatch freedom but enables advantages in grid fees and direct marketing optimisation. Catalyst models EEG-compliant operation with real generation profiles.

The innovation tender under § 39j EEG supports novel RE concepts — in particular co-location projects. Successful bidders receive a market premium on their feed-in. For BESS projects realised in combination with RE assets, the innovation tender can be a relevant revenue component.

Inertia refers to the ability to instantly provide power during a sudden frequency drop — without activation delay. Traditionally supplied by rotating masses (generators), inertia becomes scarcer as inverter-based generation grows. BESS can emulate synthetic inertia.

Capacity markets remunerate the reservation of secured generation capacity — independently of actual production. Germany has not introduced a capacity market; the current system relies on an energy-only market. In other EU markets (UK, France, Belgium, Poland), BESS already participate.