DACH BESS: shield solar revenue from negative prices

Germany’s Solar Peak Act has changed the revenue profile of newly commissioned PV projects receiving support under the Renewable Energy Sources Act. For qualifying systems commissioned from 25 February 2025, EEG remuneration is suspended during intervals when day-ahead electricity prices are negative. The change strengthens the incentive to consider flexible operation, storage, and other ways to respond to periods of surplus generation.

If you are planning a German PV-plus-BESS project, the feasibility stage is a key time to test whether storage could shift part of the plant’s output into other periods and whether the potential value justifies the added land, equipment, and engineering requirements.

RatedPower can support this early assessment by letting developers compare PV-only and PV-plus-BESS configurations, technical layouts, and selected energy and financial outputs before the design moves into more detailed engineering.

More output but weaker revenue

Solar deployment across the DACH region has increased the volume of low-carbon electricity available to the power system. At the same time, the concentration of PV generation around similar daytime hours can reduce the market value captured by solar assets when output is high, and demand or system flexibility is insufficient.

Germany has experienced particularly strong negative-price exposure. The market recorded 576 hours of sub-zero day-ahead prices in the first ten months of 2025, including 51 hours in October. In April 2026, prices were negative during 123 of the month’s 720 hours, equivalent to 17.1% of the month.

The picture is not a simple year-on-year rise, however. During the first half of 2026, Germany recorded 299 negative-price hours, compared with 389 in the cited comparison period a year earlier. This suggests that the frequency can fluctuate even as solar-heavy periods, curtailment and widening intraday price spreads continue to create revenue-management challenges.

In April 2026, the negative-price periods were concentrated largely between 10:00 and 16:00 CEST. Of the 9,754 GWh generated over the month, 4,559 GWh was delivered during periods when day-ahead prices were below zero. These figures underline the growing importance of examining not only annual output, but also when generation reaches the market.

Germany’s installed solar capacity reached approximately 116.8 GW(DC) by the end of 2025. This is significantly greater than typical system demand during many solar-heavy periods, although installed capacity should not be equated with simultaneous output. An August 2025 analysis by Modo Energy found that Germany’s solar capture rate had declined from 98% in 2022 to an average of 54% in 2025 up to the date of the analysis. The capture rate measures the price earned by solar generation relative to the average wholesale market price over the same period.

A solar capture price is the generation-weighted average wholesale price achieved during the hours in which solar produces. The capture rate expresses that price as a percentage of the average wholesale market price over the same period.

The same value pressure is visible elsewhere in the region, although national market conditions differ. In Austria, solar achieved a capture price of €88.72/MWh in October 2025, compared with an average market price of €108.02/MWh, giving a monthly capture rate of 81.5%. Switzerland had also recorded close to 300 negative-price hours by the end of October 2025. These figures should not be treated as directly comparable investment indicators. 

Forecast generation is not the same as delivered generation

Negative-price periods also show why revenue modeling should distinguish between forecast generation, actual delivered output and the price achieved when that electricity reaches the market.

In April 2026, Germany’s actual generation was below its day-ahead forecast during 80% of negative-price hours, compared with 27% of positive-price hours. The available analysis does not isolate the causes, which could include forecasting differences, commercial responses, or curtailment. Developers should therefore avoid treating day-ahead generation forecasts as a direct proxy for delivered or remunerated energy, particularly during periods of system surplus.

EEG support is becoming more responsive to market conditions

Germany has historically used the Renewable Energy Sources Act, or EEG, to provide qualifying renewable generators with defined forms of support. The Solar Peak Act, which entered into force on 25 February 2025, amended these arrangements for newly commissioned PV systems.

EEG remuneration pauses during negative-price intervals

For qualifying new PV systems from the applicable 2 kW threshold, EEG remuneration is suspended during market intervals in which day-ahead electricity prices are negative. This does not necessarily mean every project loses all revenue during those periods, as exposure depends on the project’s support mechanism, route to market, and commercial agreements.

Compensation is deferred rather than immediate

Under the Section 51a extension mechanism, qualifying periods without EEG remuneration can be added to the end of the statutory support period, subject to the applicable metering and regulatory requirements. The mechanism can preserve support duration, but it does not replace the near-term cash flow that would otherwise have been received.

For developers, the practical implication is that negative-price assumptions, metering requirements, route-to-market arrangements and the timing of compensation should be modeled explicitly rather than treated as a general reduction in annual output.

How can developers protect value in saturated DACH solar markets?

Green hydrogen electrolyzers, demand response, flexible consumption, and sector coupling can all provide routes to use electricity during periods of high renewable output. For some utility-scale solar projects, co-located BESS may offer another option by storing part of the available generation and discharging it later, subject to battery capacity, losses, cycling constraints, grid access and market prices.

Whether this improves project economics depends on the spread between charging and discharging prices, the project’s route to market, operating strategy, equipment costs, degradation and any restrictions at the point of interconnection. Storage should therefore be evaluated as a project-specific investment case rather than a guaranteed hedge against low or negative prices.

Adding storage changes a project's footprint, electrical architecture, and operating assumptions, so consider it before the PV design becomes difficult to revise. Early-stage considerations include:

• Site layout: space for battery containers or racks, power-conversion equipment, access roads, setbacks and project-specific safety clearances.

• Electrical configuration: AC- or DC-coupling, equipment selection, medium-voltage cabling and the connection between the PV, storage and interconnection facilities.

• Interconnection assumptions: charging and discharging limits, the selected connection arrangement and any requirements imposed at the point of interconnection.

• Specialist engineering: fire safety, thermal management, detailed protection studies and local code compliance require assessment by the relevant qualified engineers and authorities.

Evaluate storage trade-offs from the outset

RatedPower lets utility-scale developers and engineers create hybrid PV-plus-BESS and standalone BESS designs in the same platform. Users can assess AC- and DC-coupled arrangements, test different capacity and cycle-duration assumptions, generate preliminary layouts and compare selected technical, energy and financial outputs.

RatedPower’s arbitrage modeling can incorporate variables such as hourly electricity prices, cycling, efficiency, degradation, CAPEX and OPEX. These results can support early scenario comparison, but they should be complemented by project-specific market forecasts, contractual analysis, revenue-stacking assumptions, local compliance checks and specialist engineering before an investment decision is made.

Any energy or financial results generated during feasibility should be treated as scenario-based estimates. Actual performance and revenue will depend on market prices, operating strategy, equipment behavior, contractual arrangements, grid availability, and applicable regulation.

If you are comparing configurations, our guide to AC- and DC-coupled BESS design explains the principal trade-offs in more detail.

Bring interconnection assumptions into early-stage design

RatedPower allows teams to include relevant interconnection elements and assumptions while developing a preliminary site concept. Depending on the project type and configuration, users can define elements such as:

• The interconnection-facility type and selected configuration

• The project’s grid point and design inputs

• Substation or switching-facility elements

• Applicable transmission-line assumptions and connection paths

These capabilities help teams assess how the preliminary plant and storage concept connects to the wider project design. They do not replace the grid operator’s requirements, local compliance review, detailed protection and power-system studies, or formal connection approval.

For a closer look at how transmission requirements influence early design choices, see our guide to solar PV and the German grid.

Carry the design into engineering

Once you have identified a promising preliminary PV-plus-BESS configuration, RatedPower can help you prepare the concept for further review and engineering.

The platform can generate outputs that support review and further engineering, including:

• Design and energy reports

• Technical documentation

• Bills of materials and single-line diagrams, where supported by the selected design

• Editable site drawings

• DWG layout exports for further development in CAD tools such as AutoCAD

• 3D visualizations and applicable shading-scene exports for use in compatible third-party workflows

These outputs give engineering teams a structured preliminary design package they can review, edit, and develop further in specialist engineering and CAD tools.

RatedPower gives development and engineering teams a faster, more consistent way to compare preliminary PV-plus-BESS configurations, document key assumptions, and identify concepts for further technical and commercial assessment.

To explore the permitting and design considerations that can shape a German storage project, download our Germany BESS permitting eBook.