Executive summary

Sigenergy has showcased a utility-scale energy storage project at Sigenergy Day Europe 2026 in Stuttgart, Germany. Solarpark Pfaffenklinge combines an 11.6 MWp solar plant with a 20 MWh battery energy storage system (BESS) in Weissach im Tal. Developed with Arausol GmbH and distributor Memodo, the project features 1,660 battery modules installed directly beneath the solar panels. Construction took 20 days, while grid commissioning was completed in two hours.

Sigenergy has showcased a decentralized battery energy storage system at Solarpark Pfaffenklinge in Germany, highlighting an installation approach that places battery modules directly beneath solar panels rather than in conventional storage containers.

The project was presented at Sigenergy Day Europe 2026 in Stuttgart. It was developed in collaboration with solar specialist Arausol GmbH and distributor Memodo.

Located in Weissach im Tal, Baden-Württemberg, the site combines an 11.6 MWp photovoltaic plant with a 20 MWh battery energy storage system. The storage installation comprises 1,660 battery modules, each with a capacity of 12 kWh. The system also includes 80 hybrid inverters, each rated at 100 kW AC, and two medium-voltage transformer stations equipped with pre-installed low-voltage connections.

The battery modules use Sigenergy's SigenStack technology and are mounted directly beneath the solar panels on Arausol's ground-mounted racking system. According to the project description, this arrangement reduces field wiring and eliminates the need for cranes during installation. It also reduces civil works and limits the amount of concrete required for foundations.

Construction was completed in 20 days, while grid commissioning took two hours. The system's storage capacity can be configured using back-of-string or side-of-string mounting, allowing developers to adapt installations to project requirements and manage costs.

The project also uses SigenAgent, an AI-based energy management system that considers weather forecasts, grid conditions and electricity market prices when adjusting operations.

When electricity prices on exchanges such as EPEX SPOT turn negative, the system can stop feeding electricity into the grid and redirect surplus solar generation into the battery. If negative prices are forecast, the battery can discharge beforehand to create additional storage capacity.

The system's native DC coupling allows surplus solar electricity to flow directly into the battery, avoiding repeated AC-to-DC conversion steps. Sigenergy says this approach improves conversion efficiency by approximately 3.7% compared with AC-coupled systems.

The configuration also addresses the site's 8.8 MVA grid connection limit. Surplus electricity that cannot be exported because of the limit can be stored on the DC bus and released later when grid capacity and market conditions allow.

The project demonstrates an alternative approach to integrating battery storage with utility-scale solar generation, combining under-panel installation with AI-based energy management and direct DC coupling.