​4-hour batteries in Germany deliver 13.7% unlevered IRR at 2026 commercial operation dates, outperforming 2-hour systems despite 34% higher capex. But over 700 GW of battery storage sits in the grid queue against just 2.5 GW connected, and fundamental risks can compress returns to the point where projects no longer clear investor hurdle rates.

This is Modo Energy's Q1 2026 German BESS investment outlook, distilling three reports into what investors need to know when committing capital to German batteries:

• Part 1: Market outlook
• Part 2: Risk analysis
• Part 3: Bankable route to market structures

Key takeaways

• ​4-hour German BESS delivers 13.7% unlevered IRR at 2026 COD, against 12.2% for 2-hour systems, despite 34% higher capex (€935k/MW vs €700k/MW).
• Near-term 2-hour revenues of €240k/MW halve by 2030 as ancillary markets saturate. Wholesale arbitrage then accounts for 95% of revenue, stabilising around €125k/MW.
• ​A 50% fall in gas prices cuts day-ahead revenues by 37%. Overbuild compresses 2030 revenues by 17%. Flexible Connection Agreements reduce IRR by up to 5 percentage points.
• Grey co-location delivers 13.7% BESS-only IRR, in line with standalone returns, but it improves the queue position under Germany's proposed maturity-based connection system.
• Physical tolling dominates German BESS offtake agreements: seven of nine disclosed deals in 2025 fix 70–100% of capacity for 5–10 years, unlocking gearing of up to 85%.

For further information reach out to the authors - zach.williams@modoenergy.com and cosima@modoenergy.com

Part 1: Market outlook

​Germany's generation mix is in structural transition. Renewables grow 150% by 2040, coal exits, and nuclear is already offline. As thermal capacity shrinks, the daily price spread that batteries exploit widens. This section covers Modo Energy's fundamental view of the German BESS market: what that transition means for revenues across system durations, and why the market shifts from ancillary services to wholesale arbitrage by 2030.

German BESS delivers double-digit returns

​A 4-hour German BESS system entering commercial operation in 2026 achieves 13.7% unlevered IRR under Modo Energy's central assumptions. A 2-hour system returns 12.2%. The additional duration more than pays for the 34% higher capex - €935k/MW versus €700k/MW.

Renewable growth and thermal exit are widening the daily price spread

Renewable generation in Germany grows from 280 TWh in 2026 to 695 TWh in 2040, a 150% increase. Coal exits by 2038. Nuclear is already offline. As thermal capacity shrinks, the gap between solar-driven midday troughs and evening peaks widens. Demand grows 70% to over 1,000 TWh through electrification of transport, heating, and industry. German BESS capacity scales from 5 GW at end of 2026 to 40 GW by 2040, with 4-hour+ systems rising to 80% of the fleet.

Ancillary services dominate in 2026, wholesale arbitrage takes over by 2030

​Ancillary services account for 55% of German BESS revenues in 2026. FCR and aFRR have a combined market size of just 4.5 GW - when battery capacity exceeds that threshold, wholesale trading becomes the primary income source. By 2030, day-ahead and intraday trading account for 95% of German BESS revenue. The transition explains the economics of longer durations: a 4-hour system can shift more energy and captures more of the daily spread.

Two new revenue streams provide upside not captured in the base case

Inertia procurement launched in January 2026 and contributes €8-20k/MW/year for batteries with grid-forming inverters. Germany confirmed a capacity market in early 2026, adding an estimated €10-15k/MW/year from 2031. The exact commercial benefit will depend on the de-rating methodology, which remains undefined.

​Read the full market outlook → German BESS investment outlook: Market fundamentals

Part 2: Risk analysis

​A merchant battery is exposed to the power market for 20 years. Under Modo Energy's central assumptions, German BESS delivers 12–14% unlevered IRR - but under the most adverse market scenario, returns compress to 5.5%. This section analyses the macro risks to German BESS investments - gas prices, demand growth, and battery buildout - as well as the main project-level risks: grid fees and connection agreements.

​Gas prices are the largest macro risk to German BESS returns

Gas prices are the dominant variable in fundamental market risks. Gas sets the marginal price on most days, so when it falls, spreads compress. The downside is structurally larger than the upside: a 50% drop cuts day-ahead revenues by 37%, while a 50% rise lifts them by only 28%.

​Demand shortfalls and overbuild pose a smaller but compounding threat

Demand shortfalls have a smaller net effect on German BESS revenues, at 7-14%. Lower demand reduces high-priced events but increases negative hours that batteries monetise. These two effects partially offset. Overbuild is the medium-term concern. A 50% increase in buildout compresses 2030 day-ahead revenues by 17%. But, the 700+ GW grid queue overstates the risk. In 2025, only 40% of projected German BESS capacity actually came online.

​Flexible Connection Agreements are the largest project-level risk to German BESS

Import-export caps, ramp rate limits, and ancillary service restrictions cost up to 5 percentage points of IRR when combined. Two projects with identical market exposure can deliver very different returns depending on their connection terms.

Grid fees after 2029 add a further layer of uncertainty

Projects connecting before August 2029 have historically received a 20-year exemption from capacity charges. Projects connecting after 2029 face three new charges under the BNetzA regime.

​The capacity charge is the critical variable. Unconstrained German batteries can absorb around €20-25k/MW/year before IRRs fall below hurdle rates. FCA-constrained batteries - most new connections - hit that threshold at €10-15 k/MW/year. More significantly, recent BNetzA proposals have indicated the new regime may be applied to projects already in operation - not just those connecting after 2029. That prospect has brought many financing processes to a standstill. Final fee values may not be confirmed until late 2028, and lenders cannot size debt around a regime they cannot model.

​Read the full risk analysis → German BESS investment outlook: Risk analysis

Part 3: Bankable routes to market

​Getting a German BESS project to market in 2026 means solving two problems. First, grid access: with 78 GW approved and just 2.5 GW connected, most standalone projects face years of delay. Second, revenue structure: volatile merchant cashflows need packaging into a form lenders will finance without surrendering all the upside. Part 3 covers how to structure a BESS route to market that can actually be built and financed.

Co-location solves grid access

​Germany's TSOs published a proposal in February 2026 to replace the current first-come-first-served queue with a maturity-based system - under which co-located projects earn priority points, improving their chances of connection ahead of standalone applicants. The first application cycle is targeted for April 2026, pending BNetzA confirmation.

​Grey co-location - where a battery charges and discharges through a shared connection with an existing solar asset - earns 13.7% IRR on a BESS-only basis, in line with standalone returns, while improving queue position under the proposed maturity-based system. It requires a dedicated import-export connection rather than sharing the solar export link.

Green co-location, where the battery can only discharge into the grid and uses onsite solar to charge, and can share the existing solar connection - make it the most practical route to grid access for BESS. It earns 8.5% IRR on a BESS only basis and 2.9% on a combined basis, making it a difficult structure to finance.

How fixed-revenue structures make German BESS financeable

​Fully merchant BESS earns €115-130k/MW/year under central assumptions but drops to €70k/MW/year in a low scenario, making high gearing impossible without revenue stabilisation. Fixed-revenue structures solve this, each trading a different share of merchant upside for debt capacity: a full toll locks returns at 12% and supports 85% gearing but surrenders all merchant upside, while a partial toll protects against the downside the merchant structure lacks while retaining the upside the full toll forfeits - delivering 9-17% unlevered IRR across scenarios.

Which structure fits which investor

​Structure choice follows investor type and operational capability. Developers maximising leverage for capital recycling favour full tolls, with utilities as dominant offtakers - battery capacity adds value beyond trading through hedging imbalance exposure and enabling 24/7 corporate PPAs. Those retaining dispatch control layer partial tolls with energy traders seeking revenue exposure without physical dispatch. Floor and share structures are emerging as an alternative for industrials with large energy procurement mandates but no trading infrastructure. Fully merchant exposure remains the domain of balance-sheet investors and trading houses with full risk appetite and no leverage requirement.

​Read the full routes-to-market analysis → German BESS investment outlook: Bankable routes to market

Three regulatory decisions that will determine the German BESS pipeline in 2026

2026 is a critical year for German battery storage regulation. BNetzA's grid fee consultation will determine whether post-2029 projects remain financeable. The capacity market's de-rating methodology will set whether batteries receive 50% or 90% of the clearing price. The Mispel regulation, if finalised, unlocks co-location at scale and could accelerate the pipeline beyond current projections.