How we read regulation: section 17(2b) EnWG in project practice

Since February 2025 grid operators may connect plants although capacity is not sufficient at every hour. The condition is a flexible connection agreement under section 17(2b) EnWG: the applicant accepts that feed-in or offtake will be limited during congestion.¹

In conversation this is often presented as a shortcut — a way around the queue. It is that too. But it is a trade, and the price is in the agreement, not in the statute.

What is actually negotiated. Three quantities matter: how often curtailment may occur, how deep it goes, and in which hours. An agreement limiting curtailment to a few percent of annual hours is something entirely different from one granting the operator unlimited access. Both are called a flexible connection agreement.

Why the operating mode decides. For storage running Arbitrage, curtailment often falls in hours of high generation and low prices — hours in which it would be charging rather than discharging anyway. The revenue loss is then small.

For storage selling balancing services the arithmetic differs. Prequalified capacity must be deliverable. A limitation barely noticeable in the arbitrage case can exclude participation here.

What that means for design. Before signing a flexible agreement, a simulation belongs on the table: how often would the limitation have applied over the past three years, in which hours, and what would that have cost in the chosen marketing model? Without that figure one signs a contract over a quantity one does not know.

The other side of the ledger. Against it stands the value of time gained. With 574 GW of connection requests and 54 GW of offers in 2025, a connection two years earlier may be worth more than the revenue lost in curtailed hours.² That trade-off can be calculated. It cannot be guessed.

What will change. From 2027 the grid connection package provides for a formalised procedure with statutory prioritisation; storage in co-location with renewable plants is to be connectable with priority.³ The value of the flexible agreement then shifts: it remains a tool but loses its character as the only way out.