Applications of the Nexus-e platform

The role of flexibility providers in shaping the future energy system

As part of the development of the Nexus-​e platform, this first study sponsored by the Swiss Federal Office of Energy implements the Nexus-​e core modules to research the role of flexibility providers in shaping the future Swiss electricity system.


In 2020, we have successfully completed Phase 1 of the Nexus-e project, including the pilot project “The role of flexibility providers in shaping the future energy system”.

Read our Scenario Results report to find out

▪ What are potential pathways for the future Swiss electricity system?
▪ What is the need for flexibility in the projected Swiss electricity system?
▪ Who provides the required flexibility?
▪ What are the macroeconomic and environmental impacts of the future Swiss electricity system?

Simulation Framework and Interfaces

Input Data and System Setup

Validation and Calibration of Modules

GemEl Module Documentation
CentIv Module Documentation
DistIv Module Documentation
eMark Module Documentation
Cascades Module Documentation


The future Swiss power system, which is envisioned in the Swiss Energy Strategy 2050, has to overcome the following challenges: enabling deep decarbonization, the integration of a higher share of renewables and distributed supply, the phase-out of nuclear power stations, achieving improved energy efficiency, and maintaining system security and resilience. To enable this transition, flexibility in the power system is getting increasingly crucial.


(1) What are the potential pathways for the future Swiss electricity system?

New PV installations replace nuclear capacity to a large extent, with some investments in biomass and PV-batteries, but no investment in grid-batteries and wind power. Between 2030 and 2040, the phase-out of investment subsidies makes investments in PV less attractive, resulting in a stagnating PV capacity. Decreasing PV prices and the uptake of PV-batteries that improve the economic viability of self-consumption, spur PV installations, resulting in 25.4 – 31.1 GW of PV capacity by 2050. By 2050, PV is responsible for the largest share (i.e., 32.6-35.5%) of electricity consumption, followed by hydro dam (26.0-28.3%) and hydro RoR (15.9-17.4%). Additionally, as nuclear gets phased out, imports become a larger contributor to the supply of electricity in Switzerland with up to 5.7% in 2050. Critical, however, is the time between 2030-2040, when the stagnating PV capacity cannot substitute nuclear phase-out fully, resulting in substantially higher net imports of up to 16.5% of the annual demand. Yet, renewable energy targets are achieved in all scenarios and years, even in 2040.

Annual electricity generation (left) and installed generating capacity (right) in the Baseline Scenario.

(2) What is the need for flexibility in the projected Swiss electricity system?

We analyze the need for flexibility across a range of timescales, from seasonal to sub-hourly scales. First, the seasonality of the net load increases in all future years due to the increasing PV penetration. This trend indicates the need for greater seasonal flexibility that could impact the operation of hydro storages or other generators as well as the pattern of imports and exports. Second, the increasingly dynamic pattern of the net load on an hourly and daily basis emphasizes the need for fast ramping flexible capacities such as hydro dams and gas-fired generators along with storages and load shifting units like pumped hydro, battery storage systems, or Demand- Side Management. Third, tertiary reserve requirements increase from year-to-year as new PV investments are added. Overall, the increases in tertiary requirements are noticeable, increasing upward and downward reserves by almost 100% and 50%, respectively, by 2050. Fourth, short-term system stability is jeopardized by the increased share of non- dispatchable units.

Need for flexibility in the Baseline Scenario. Average net load during month illustrates seasonality of flexibility need (left), hourly net load for one week with high solar radiation illustrates diurnal and daily changes in flexibility need (right).

(3) Who provides the required flexibility?

The need for flexibility is met with different flexibility sources. First of all, net imports play a crucial role for addressing the increasing requirement for seasonal flexibility. By 2050, the monthly net imports follow closely the seasonal net load pattern. Also, the seasonality of the hydro dam generation becomes more pronounced by 2050, making hydro dams essential for providing seasonal flexibility. Besides providing seasonal flexibility, Swiss generators also have to adjust their operation to account for the increasingly rapid changes in the hourly net load. Mostly imports and exports as well as hydro dams, but also hydro pumps, hydro run-of-river, PV-batteries, and Demand-Side Management react rapidly to help provide the necessary supply along with more frequent curtailments of non-dispatchable units in future years. However, higher shares of flexible PV-batteries and Demand- Side Management resources successfully smooth the hourly net load and thus reduce the reliance on imports/exports for hourly flexibility. Furthermore, the existing Swiss dispatchable capacities are expected to be able to supply the reserves that are required to cope with the sub-hourly forecast uncertainty of PV investments in all scenarios. In all projections for the future Swiss power systems, the risk of systemic failures initially increases but can be addressed by upgrading one transmission line. PV- batteries and DSM can even further reduce such risk and strengthen system security.

Providing flexibility in the Baseline Scenario. Monthly electricity generation illustrates seasonal flexibility provision (left), hourly electricity generation illustrates how diurnal and daily changes in flexibility need is met (right).

(4) What are the macroeconomic and environmental impacts of the future Swiss electricity system?

Besides the technical perspectives, we also assessed the future Swiss electricity system from the macroeconomic and environmental perspectives. However, the differences between the scenarios for GDP, gross investments, and carbon emissions are below 0.02%. Therefore, we conclude that, as expected, our varying scenario inputs (i.e., the runtime of nuclear power plants, battery cost development, DSM potential) do not introduce substantial macroeconomic and environmental differences.

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