On January 31, 2025, the German government passed an amendment to the Renewable Energy Sources Act (EEG) that regulates the overbuilding of grid connection points, known as "cable pooling." The new Section 8a of the EEG 2023 generally allows plant operators to select an already-used connection point. Furthermore, grid operators are obligated to specifically assess the feasibility of overbuilding connection points if capacities at the nearest connection point are lacking.
When overbuilding occurs, a so-called Flexible Grid Connection Agreement is concluded to ensure that the newly connected plant does not exceed the permissible feed-in capacity (or only exceeds it within limited time windows). As a result, the operational flexibility of the additionally connected plant is restricted. Overbuilding is particularly beneficial for hybrid technologies that utilize the grid connection at different times.
A study by the German Renewable Energy Federation (BEE), published in 2024, modeled overbuilding scenarios and concluded that overbuilding up to 150% of a connection point with equal shares of photovoltaic and wind capacity does not produce significant energy surpluses or revenue losses compared to stand-alone systems. Link
For connections overbuilt with battery storage, revenue losses are even lower because the specific feed-in profiles differ more significantly. Ulrike Gunnemann of BayWa r.e. presented concrete figures at the SolarForum Plus in November 2024: Overbuilding a 70 MW solar park with a 17.5 MW battery storage system (125% overbuilding) results in revenue losses of only 0.4% for the storage system compared to a stand-alone setup. Overbuilding with a 35 MW battery storage system (150% overbuilding) leads to revenue losses of 1.5%. However, this must be weighed against two significant advantages: first, enabling the grid connection for the storage system in the first place, and second, significant reductions in investment and operational costs for both the solar park and storage system through the shared grid connection.
Project developers should therefore focus on existing connection points and consider overbuilding when planning grid connections for small to medium-sized facilities. To identify local NVPs available for overbuilding, dvlp.energy has launched the GridConnect platform. GridConnect utilizes a large database of registered NVPs and can connect them with locally active project developers. Detailed information on the process can be found at the following. link
