Unlocking Revenue Potential: Wind + BESS in Germany – Together with Fluence
The energy transition in Germany is facing headwinds. Increasing negative price hours, stricter EEG rules, and grid limitations are eroding the profitability of standalone wind projects. Yet, as our recent Wind + BESS feasibility study in Cooperation with Fluence shows, co-locating battery storage with wind power plants can transform financial outcomes and secure long-term resilience.
The Challenge: Falling Yields for Wind Assets
- Negative market prices are rising, reducing guaranteed income for wind projects.
- Grid congestion leads to curtailed production and lost revenues.
- Price cannibalization from uncontrolled renewable generation drives down capture rates.
In short, wind projects alone are increasingly exposed to volatile markets and regulatory risks.
The Solution: Co-Located Wind + BESS
By integrating a Battery Energy Storage System (BESS) directly at the wind site, operators can:
- Store excess generation during low-price or negative-price hours.
- Sell electricity strategically in Day-Ahead (DA) and Intraday (ID) markets.
- Participate in ancillary services like aFRR (Automatic Frequency Restoration Reserve), unlocking new revenue streams.
This controlled production improves grid integration and stabilizes cashflows.
Revenue Breakdown: Where the Money Comes From
The study simulated 2,592 scenarios using the Catalyst platform, analyzing different storage sizes, durations, and market setups. Key findings:
- Day-Ahead Market: ~42.7% of total profit
- Wind Market Premium (DA for wind): ~36.5%
- Intraday Market: ~9.1%
- aFRR Positive Market: ~11.6%
Together, these markets create a diversified revenue portfolio, reducing dependence on volatile wholesale prices.
Business Case Highlights
For a 25 MW wind park with 20 MW / 4h LFP BESS (80% oversizing, green co-location):
- Net Present Value (NPV): €14.6 million
- Internal Rate of Return (IRR): 14.0%
- Break-even (discounted): ~12 years
- Total Market Profit (2026–2045): €174 million
The storage system, despite smaller CapEx compared to the wind asset, contributes more than half of the project’s revenues.
Sizing & Market Strategy Insights
- Optimal sizing: ~80% oversizing with 4-hour duration.
- Multi-market participation (DA + ID + aFRR) yields the best performance.
- Larger storage assets capture more curtailed energy but don’t always justify higher CapEx.
- Market price assumptions remain the biggest sensitivity factor: Wind-only projects turn negative in low-price scenarios, while Wind + BESS stays positive.
Conclusion
Wind + BESS is not just a technical upgrade—it’s a financial safeguard. By strategically dispatching stored energy across multiple markets, co-located projects can:
- Improve profitability,
- Enhance resilience against regulatory changes,
- And secure long-term viability in Germany’s evolving energy landscape.
“The BESS can act as insurance and save the wind project performance.”
