Headline: Bridging the Gap Between Planning and Reality: Industry Experts Warn of Systematic Underestimation in Germany’s 2040/2045 Grid Scenarios

BERLIN – As Germany navigates the complex transition toward a climate-neutral industrial economy, the roadmap for its most critical infrastructure—the power grid—has come under intense scrutiny. On September 28, 2026, the German Transmission System Operators (TSOs) released their draft for the Scenario Framework for Electricity 2040/2045 (Version 2027). While the document is intended to serve as the foundational blueprint for the country’s Network Development Plan (Netzentwicklungsplan or NEP), it has sparked a significant debate regarding its accuracy and foresight.

The Association of New Energy Business (Bundesverband Neue Energiewirtschaft, bne) has issued a comprehensive critique during the consultation process led by the Federal Network Agency (BNetzA). The bne warns that while the TSOs have made methodological strides, the current draft risks "planning past the market," potentially leading to billions in misallocated investments and a grid that is fundamentally unequipped for the realities of the 2040s.

Main Facts: The Blueprint for Germany’s Energy Future

The Scenario Framework is more than a technical forecast; it is a legally mandated projection that determines how many high-voltage lines, substations, and storage facilities Germany will build over the next two decades. The 2040/2045 version is particularly critical as it covers the period in which Germany aims to achieve total climate neutrality.

The TSO Proposal
The draft presented by the four German TSOs (50Hertz, Amprion, TenneT, and TransnetBW) outlines various development paths—labeled Scenarios A, B, and C. These paths vary based on assumptions regarding the speed of electrification in heating and transport, the ramp-up of hydrogen infrastructure, and the expansion of renewable energy sources.

The Methodological Shift
The bne acknowledges that the 2027 version shows "positive evolution." The TSOs have improved how they model certain regional distributions and have refined their data sets compared to the previous 2025/2037 framework. However, the industry association argues that these improvements are overshadowed by conservative assumptions that fail to reflect the explosive growth of the solar and storage markets.

The "Narrow Funnel" Problem
A central point of contention is the lack of diversity between the scenarios. The bne argues that Scenarios B and C are nearly identical, creating a "narrow funnel" that deprives policymakers and market participants of genuine insights into different transformation paths. Most alarmingly, none of the TSO scenarios currently project a 100% renewable energy supply by 2045, despite this being a core pillar of German federal law and climate targets.

Chronology: The Evolution of Grid Planning

To understand the weight of the current dispute, one must look at the timeline of German grid planning and the recurring pattern of underestimating renewable expansion.

1. 2014: The Precedent of Underestimation. In the 2014 Scenario Framework (targeting 2025), the TSOs and BNetzA approved a "highly ambitious" scenario (C2025) that predicted 54.1 GW of installed photovoltaics (PV). In reality, by the end of 2025, Germany had reached approximately 110 GW—more than double the "ambitious" forecast. This discrepancy has led to the current "grid bottleneck" crisis, where solar parks are frequently curtailed because the infrastructure planned a decade ago was too small.
2. 2023-2024: The Reform of §14a EnWG. The German government introduced new regulations requiring heat pumps, electric vehicle chargers, and home storage systems to be "grid-friendly." This marked a shift toward decentralized flexibility, which the bne argues is not yet fully integrated into the new 2040/2045 draft.
3. September 2026: The Draft Release. TSOs submit the Version 2027 draft for public and institutional consultation.
4. Present (Consultation Phase): The BNetzA collects statements from stakeholders like the bne. The final Scenario Framework will be approved after this feedback is processed, serving as the basis for the 2027-2037/2045 Network Development Plan.

Supporting Data: Technical Discrepancies and Market Realities

The bne’s critique is backed by specific technical data points where they believe the TSOs’ modeling diverges from engineering and market logic.

AC vs. DC Power Modeling
A major technical hurdle in the current draft is the treatment of Photovoltaic (PV) power. The TSOs often calculate grid load based on the DC (Direct Current) capacity of solar modules. However, the bne emphasizes that the "grid-effective AC power" (Alternating Current) is what actually enters the network. In modern solar parks, the AC output is often significantly lower than the DC capacity to optimize inverter use. By failing to use AC-based modeling, the TSOs may be overestimating the peak load of individual plants while underestimating the total number of plants the grid can actually accommodate.

The Rise of Co-Location
One of the most significant trends in the energy industry is "co-location"—the pairing of solar or wind farms with large-scale battery storage at the same grid connection point.

• The bne Recommendation: Co-location batteries should be modeled using the same regional logic as PV plants.
• Grid Usage: The association argues that these batteries will not just store solar power but will also draw power from the grid during periods of excess wind energy (negative prices).
• The 25% Rule: The bne suggests that the assumed grid-draw capacity for these storage units should not be set lower than 25% of their discharge capacity to reflect realistic market behavior.

The Flexibility Gap
The draft assumes a relatively rigid behavior for prosumers (households with solar and EVs). The bne points out that by 2040, the rollout of Intelligent Metering Systems (iMSys), dynamic electricity tariffs, and variable grid fees will be complete.

• Current Reality: Today, §14a of the Energy Industry Act (EnWG) already mandates grid-friendly control for wallboxes and heat pumps.
• Future Projection: The bne argues that TSOs are stuck in a "digitalization bottleneck" mindset of the 2020s, failing to realize that by 2040, decentralized assets will be both market-oriented (responding to prices) and grid-oriented (responding to local congestion) simultaneously.

Official Responses: Industry Demands and Regulatory Pressure

Robert Busch, CEO of bne, has been vocal about the risks of the current draft. "If we plan the grid based on the wrong assumptions today, we will build the wrong infrastructure for tomorrow," Busch warned. He emphasized that Scenario C must, at a minimum, depict a 100% renewable electricity supply to provide a robust stress test for the grid of the future.

The bne’s Primary Demands to the BNetzA:

• Mandatory 100% Renewable Scenario: At least one scenario must reach full decarbonization by 2045 to align with legal climate targets.
• Revised Storage Logic: Explicitly describe and model co-location batteries and assume a higher degree of retrofitting for existing wind farms with storage (targeting 15% of all wind farms by 2040).
• Digitalization Parity: Update assumptions on "load flexibility" to reflect a fully digitalized energy system where consumers actively participate in balancing the grid.

The TSO Perspective:
While the TSOs have not yet issued a formal rebuttal to the bne’s specific consultation filing, their draft emphasizes the need for "security of supply." TSOs traditionally lean toward conservative estimates to ensure that the grid remains stable even under "worst-case" scenarios where renewable output might be lower than expected. They argue that their scenarios provide a "realistic" rather than "idealistic" pathway.

Implications: What is at Stake?

The discrepancy between the TSO draft and the bne’s market-based view has profound implications for Germany’s economy and its climate goals.

1. Stranded Assets vs. Bottlenecks
If the TSOs underestimate the speed of the solar and storage rollout (as they did in 2014), the result will be a grid that is too weak. This leads to "re-dispatch" costs—where the grid pays wind farms to turn off and gas plants to turn on because power cannot be moved from north to south. These costs already exceed billions of euros annually and are paid by consumers via grid fees. Conversely, over-building in the wrong areas could lead to "stranded assets"—infrastructure that is paid for but not utilized.

2. Integration of European Standards
The bne highlights that the "European Grids Package" and the "Network Code on Demand Response" are currently being finalized in Brussels. These regulations will mandate a much higher level of consumer participation and cross-border flexibility. If Germany’s Scenario Framework does not anticipate these changes, the country may find itself out of sync with the EU’s unified energy market.

3. The Role of Distribution Grid Operators (VNBs)
The Scenario Framework doesn’t just affect the "electricity highways" (TSOs); it trickles down to regional distribution grids. Since regional scenarios are derived from the TSO framework, a flaw at the top of the planning hierarchy creates a "domino effect," leading to incorrect expansion plans at the local level where most solar and EVs are actually connected.

4. Economic Competitiveness
A grid that is planned efficiently and accommodates 100% renewables more quickly will lead to lower long-term energy prices. By underestimating the role of co-located storage and flexible loads, the TSO draft might inadvertently support a more expensive, centralized backup system (such as prolonged reliance on gas-to-power) that could have been avoided through better utilization of decentralized assets.

Conclusion

The consultation for the Scenario Framework 2040/2045 represents a crossroads for the German Energiewende. The bne’s intervention serves as a reminder that infrastructure planning cannot exist in a vacuum, isolated from the rapid pace of technological innovation and market dynamics. As the Federal Network Agency reviews these statements, the challenge will be to balance the TSOs’ inherent caution with the industry’s drive for a more flexible, 100% renewable-ready grid. The final version of this framework will ultimately decide whether Germany’s grid becomes an enabler of the green transition or its most significant bottleneck.