Flexible Connection Agreements (FCAs) are spreading fast across Germany, and a common design is emerging: limits that move with local grid conditions, pegged to the live output of nearby wind and solar. Schleswig-Holstein Netz has published one of the first concrete templates, a preview of the terms developers will face across the country.

The base case headline is reassuring: A limited renewables-pegged import-export cap cuts revenues by less than 2%. It lines up with what a merchant battery would choose to do most of the time anyway: charge when renewables are high and prices are low, and discharge when they are low and prices rise. The cap only bites when local generation and national price signals diverge, costing a manageable 1.7% of revenue. That is an acceptable trade for faster connection.

​The damage comes from what gets layered on top. A 23:00 to 05:00 overnight charging cap at 25% of rated power costs a full point of IRR on its own. That is as much as a 6%/min ramp limit and a 30% ancillary restriction combined.

Key takeaways

• Schleswig-Holstein Netz ties battery limits to local renewable load factors, with three cap variants. A static overnight charging cap, ramp rates and ancillary service restrictions may also apply.
• The import-export cap alone is an acceptable compromise, up to a certain extent. Under Variant 1 it costs just 0.3 points of IRR. The strictest Variant 3 costs up to 1.6 points.
• The overnight charging window does outsized damage. Capping import to 25% from 23:00 to 05:00 costs over 1.0 point of IRR, as much as the ramp limit and ancillary cap combined.
• That window restricts charging during the daily demand trough, even when wind is still generating.
• In negotiation, the two clauses worth fighting are the overnight window and the ramp limit's reach into ancillary delivery.

If you want to learn more, reach out to the author - cosima@modoenergy.com.

The cap tracks the weather, then three FCA restrictions stack on top

Schleswig-Holstein Netz sets the battery's allowed power band from the live output of local wind and solar. When renewables run high, discharging is restricted. When they fall away, charging is restricted.

Three variants set how hard the cap bites. Variant 1 starts cutting discharge once local renewables pass 50% of nameplate, reaching zero at 100%. Variant 2 starts at 40%. Variant 3 starts at 30% and hits zero at 60%.

Three further restrictions can sit on top. An overnight window from 23:00 to 05:00 caps charging to 25% of rated power, whatever the renewable output. A ramp limit holds power change at the connection point to 6% per minute. And ancillary participation is capped at 30% of installed capacity, with no primary frequency response.

Why does the overnight charge cap cost as much as the ramp limit and ancillary cap combined?

We modelled every combination on a 100 MW, 4-hour battery with a 2027 COD.

The import-export cap alone has the lowest impact. Under Variant 1, 25-year average revenue falls 1.7% and IRR holds at 11.3%, against an 11.6% unconstrained base.