Assumptions and sources
How the model calculates
- For each month of an average year, consumption is compared with the generation that cannot be controlled: run-of-river plants, nuclear, waste, wood and biogas, wind and solar.
- If power is missing, any seasonal battery delivers first, then the storage lakes.
- The lakes fill with their natural inflow. Once they are full, the water has to go through the turbines straight away.
- Whatever is still missing is imported.
- A surplus charges the battery. The rest is exported or curtailed. Solar power is curtailed first.
- The year is calculated again and again until the lakes and the battery are as full at the end of the year as at the start.
Costs are calculated as an annual payment: construction costs spread over the lifetime with interest, plus operation. The interest rate is real, that is, without inflation. All the code is open.
Electricity system
| Quantity | Value | Source |
|---|---|---|
| Consumption today (national consumption) | 62.1 TWh, average of 2024 and 2025 | 1 |
| Consumption 2050 | Electric cars +13 TWh, heat pumps +6.6 TWh, efficiency −13 TWh, total around 68.7 TWhElectrolysis and large heat pumps not included | 15 |
| Run-of-river plants | 17.8 TWh in an average year, monthly profile 2016–2025 | 41 |
| Natural inflow into the storage lakes | 19.4 TWh per year, 19 % of it in winterMonthly profile calculated from output, lake levels and pumping energy | 413 |
| Storage lakes | 8.9 TWh, used between 6 and 92 % | 23 |
| Nuclear | Capacity factor 88 %, monthly profile 2016–2025 | 21 |
| Solar, roofs (Swiss Plateau) | 900 kWh per kW and year, 25 % in winter, profile of Swiss plants 2024/25 | 17 |
| Solar, facades | 644 kWh per kW, 39 % in winterMonthly profile is our own estimate | 11 |
| Solar, alpine | 1’470 kWh per kW, 44 % in winterMonthly profile is our own estimate | 1113 |
| Solar potential of buildings | Roofs 50 TWh, facades 17 TWh per year | 8 |
Costs
| Quantity | cheap | middle | expensive | Source |
|---|---|---|---|---|
| Solar, roofs, construction costs | 800 CHF/kW | 1’200 CHF/kWAverage of the size classes: large roofs 660, single-family house 2’500 | 1’900 CHF/kW | 910 |
| Solar, facades, construction costs | 1’500 CHF/kW | 1’900 CHF/kW | 2’600 CHF/kW | 10 |
| Solar, alpine, construction costs | 2’600 CHF/kW | 3’900 CHF/kW | 4’500 CHF/kW | 111012 |
| Solar, operation and maintenance | Roofs 20, facades 25, alpine 70 CHF per kW and yearequivalent to 2 to 5 ct./kWh | 11 | ||
| Solar, lifetime | 30 years | 11 | ||
| Wind, costs | 12 ct./kWh | 15 ct./kWhweak source, industry figure | 18 ct./kWh | 34 |
| Seasonal battery, construction costs | 150 CHF/kWh | 220 CHF/kWhfully built in Switzerland, including grid connection | 350 CHF/kWh | 2324 |
| Seasonal battery, lifetime, losses | 20 years, 90 % efficiency, 1.5 % self-discharge per month | 25 | ||
| New nuclear plant, construction costs | 6’000 CHF/kW | 9’000 CHF/kWwithout interest during construction; the model calculates this from the interest rate and construction time | 16’000 CHF/kW | 28293130 |
| New nuclear plant, construction time | 8 years | 10 years | 15 years | 3230 |
| New nuclear plant, operation, fuel, waste disposal | 39.3 CHF/MWh | 29 | ||
| New nuclear plant, lifetime and capacity factor | 60 years, 88 % | 292 | ||
| Existing nuclear plants, operating costs | 5 ct./kWh | 28 | ||
| Interest rate for renewables and batteries (real) | 2 % | 3 % | 5 % | 14 |
| Interest rate for new nuclear plants (real) | 3 % | 5 % | 7 % | 29 |
| Imported power, price | 12 ct./kWh | 35 | ||
| Surplus in summer, value | 0 ct./kWh; baseload power from nuclear and wind: 4 ct./kWh | 35 |
Image credits
Photos from Wikimedia Commons. The illustrations were created by an image generator from a text description. They do not show real plants.
- Photo: The Grande Dixence dam with the turquoise Lac des Dix, surrounded by mountains. Jérémy Toma, CC BY-SA 4.0
- Photo: The Lago di Lei reservoir between green mountain slopes, with glaciers in the background. Capricorn4049, CC BY-SA 4.0
- Photo: A large flat roof covered with solar panels, with green meadows of eastern Switzerland behind it. Cleanfix Reinigungssysteme AG, CC BY-SA 4.0
- Photo: A cloud of steam above the cooling tower of the Gösgen nuclear power plant against the evening sky. Joris Egger, CC BY-SA 4.0
- Photo: Wind turbines on the Jura pastures of Mont Crosin under a blue sky. Rapipolo, CC BY-SA 4.0
- Photo: Two battery storage containers in a field in Rheineck. Kecko, CC BY 2.0
- Illustration, AI-generated: A sunny winter day in the Alps, a partly frozen reservoir with a curved dam, larch trees and snow-covered peaks
- Illustration, AI-generated: Rows of solar panels on a snowy alpine slope in the morning sun, with a sea of fog below
- Illustration, AI-generated: Endless rows of white battery containers on the Swiss Plateau in evening light, a village at the edge and the Alps behind
- Illustration, AI-generated: Winter evening in an Alpine valley: a high-voltage line runs down the snowy slope to a village with lit windows, the peaks in the last evening light
Sources
Titles in the original language of the source.
- Bundesamt für Energie (BFE) (2000–2026): Schweizerische Elektrizitätsbilanz, Monatswerte (opendata ogd35)
- Bundesamt für Energie (BFE) (2026): Schweizerische Elektrizitätsstatistik 2025
- Bundesamt für Energie (BFE) (2000–2026): Füllungsgrad der Speicherseen, Wochenwerte (opendata ogd17)
- Bundesamt für Energie (BFE) (2026): Statistik der Wasserkraftanlagen der Schweiz, Stand 31.12.2025
- Bundesamt für Energie (BFE) (2014): Rentabilität der bestehenden Wasserkraft, Bericht zuhanden der UREK-N
- Bundesamt für Energie (BFE) (2014): Neues Fördermodell Wasserkraft, Bericht zuhanden der UREK-N
- BFE / Swissolar (2026): Statistik Sonnenenergie, Referenzjahr 2025
- Bundesamt für Energie (BFE) (2019): Schweizer Hausdächer und -fassaden könnten jährlich 67 TWh Solarstrom produzieren
- BFE / EnergieSchweiz (2026): Photovoltaikmarkt: Preisbeobachtungsstudie 2025
- Swissolar (2025): Solarmonitor Schweiz 2025
- Bundesamt für Energie (BFE) (2026): Technologiemonitoring Photovoltaik, V1.2
- Alpiq / Gondosolar (2023): Wirtschaftlichkeitsberechnung zum Baugesuch Gondosolar
- ZHAW (2023): Photovoltaik in den Alpen liefert im Winter bis zu viermal mehr Strom
- UVEK (2026): Kalkulatorische Kapitalkostensätze für Fördergesuche 2026
- BFE / Prognos, TEP, Infras (2020/2022): Energieperspektiven 2050+, Kurzbericht
- Fedlex (Stand 2026): Energiegesetz (EnG), SR 730.0, Art. 2
- Fedlex (2025): Stromversorgungsverordnung, Art. 19c (Garantierte Nutzung der Flexibilität)
- CKW, WWZ und weitere Netzbetreiber (2025): Gemeinsame Medienmitteilung: Regelung der Solarstromeinspeisung (70 %)
- UNSW Sydney (Poster, Sandia PV Reliability Workshop) (2024): Clipping and Curtailment Degradation
- ElCom (2025): Update Winterproduktionsfähigkeit
- ETH Zürich / PSI (2026): Weissbuch Kernenergie (DOI 10.3929/ethz-c-000801811)
- VSE / Empa (2025): Energiezukunft 2050, Update
- BloombergNEF (2025): Lithium-Ion Battery Pack Prices Fall to $108 per Kilowatt-Hour
- NREL (2025): Cost Projections for Utility-Scale Battery Storage: 2025 Update
- Tesla (2023): Megapack 2 XL Datasheet
- Energy-Storage.news (2024): CATL unveils BESS with 6.25 MWh per container
- Nant de Drance SA (2022): Das Kraftwerk
- Bundesrat (2025): Botschaft zur Volksinitiative «Blackout stoppen» und indirektem Gegenvorschlag (BBl 2025 2563)
- BAK Economics im Auftrag von economiesuisse (2026): Volkswirtschaftliche Auswirkungen eines KKW-Ersatzneubaus
- Cour des comptes (2025): La filière EPR : une dynamique nouvelle, des risques persistants
- Reuters via AJ Bell (2026): UK’s Hinkley Point nuclear plant costs raised to £35 billion
- SRF über Akademien der Wissenschaften Schweiz (2025): Ein allfälliges neues AKW wäre um 2050 in Betrieb
- Axpo (2023): Energy Report Windenergie
- Germany Trade & Invest (2024): Branche kompakt: Windenergie Schweiz
- Fraunhofer ISE, Energy-Charts (Daten: Bundesnetzagentur / SMARD.de, CC BY 4.0) (2023–2026): Day-Ahead-Preise Gebotszone Schweiz, stündlich
- ElCom (2026): Newsletter 07/2026: Wasserkraftreserve 2026/27
- Bundesrat (2025): Runder Tisch Wasserkraft: Stand der Projekte
- Bundesamt für Statistik (BFS) (2025): Bruttoinlandprodukt 2024 zu laufenden Preisen: 854 Mrd. Franken
- MeteoSchweiz (1991–2020): Heizgradtage (Normwerte), Grundlage für das Profil der Wärmepumpen