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. Remuneration consists of an availability payment (regardless of activation) plus an activation payment.

The intraday market enables continuous trading until shortly before delivery. 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 clearing 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 volatile — as a stack complement alongside ancillary services it is highly effective.

Under the market premium model, a direct marketer (Direktvermarkter) sells renewable electricity on the spot market (day-ahead & intraday) on behalf of the plant operator. The government compensates the difference via the statutory market premium. For co-located BESS, direct marketing enables revenue optimization by coordinating feed-in and storage dispatch.

The fixed feed-in tariff under EEG applies to renewable installations below the mandatory direct marketing threshold. It provides fixed price certainty but no market optimization potential. While irrelevant for utility-scale BESS, it applies to small-scale co-located assets.

Green storage assets (Grünstromspeicher) under EEG charge exclusively from co-located RE generation. While this constraint restricts dispatch flexibility (no grid charging), it eliminates charging grid fees and preserves statutory EEG privileges. Catalyst models EEG-compliant operation using real generation profiles.

The innovation tender (§ 39n EEG 2023) supports combination projects (Anlagenkombinationen) pairing renewable generation with BESS. Successful bidders receive a sliding market premium on top of spot market revenues, offering exceptional revenue potential through price arbitrage.

Inertia refers to the ability to instantaneously inject or absorb power during frequency events without any activation delay. Traditionally provided by rotating masses of synchronous generators, inertia becomes scarce as renewables grow. BESS can emulate synthetic inertia using grid-forming inverters.

Capacity markets remunerate the reservation of secured dispatchable capacity to ensure security of supply — independently of actual energy production. While Germany historically relied purely on an energy-only market with strategic reserves, it is now introducing a market-wide capacity mechanism. BESS actively participate in capacity markets across several European countries.