How much battery storage does Germany need to survive periods of low wind and solar?
Select a pre-calculated scenario or adjust parameters below.
Effective import depends on whether neighbors also have low RE. Set based on your assumption.
Adjust parameters and click Calculate to see results.
| Total electricity demand (2024) | 466 TWh |
| Peak demand (winter) | ~80 GW |
| Installed RE capacity (2024) | ~186 GW (PV 99 + Wind 73 + Bio 9 + Hydro 5) |
| RE share of generation (2024) | ~62% |
| Grid-scale battery storage (H1 2026) | 3.4 GW / 5.7 GWh |
| Home battery storage (2025) | ~20 GWh |
| Pumped hydro storage | ~6.4 GW / ~40 GWh |
| BEV fleet (Jan 2026) | 2,034,260 |
| BEV annual sales (2025) | 545,142 (19.1%) |
| Total passenger cars | 49,500,000 |
| Gas power plant capacity | ~34 GW |
| Battery cell cost (2025) | ~100 EUR/kWh |
| Battery system cost (installed, Europe) | 165-240 EUR/kWh |
| Battery system cost (projected 2030) | ~80-120 EUR/kWh |
Sources: BNetzA, Fraunhofer ISE, KBA, BNEF, Modo Energy, SMARD
Short-duration BESS (Li-ion, C0.5, 2-4h)
| Product | Capacity | Cost |
|---|---|---|
| CATL TENER | 6.25 MWh/unit | n/a |
| Tesla Megapack 2 XL | 3.9 MWh/unit | ~266 USD/kWh |
| BYD MC Cube-T | 6.4 MWh/unit | n/a (15yr warranty) |
| Fluence Gridstack Pro | 5.6 MWh/unit | n/a (87% RTE) |
Long-duration storage (8h+)
| Technology | Duration | Cost | RTE |
|---|---|---|---|
| Vanadium flow (Invinity, CellCube) | 4-24h | 300-500 EUR/kWh | ~75% |
| Iron-air (Form Energy) [1] | 100h | ~33 USD/kWh installed [2] | 35-50% |
| Iron-air (Ore Energy, NL) [3] | 100h | TBD (pilot stage) | TBD |
| Compressed air (Hydrostor) | 8-24h | 150-300 USD/kWh | 60-65% |
| Gravity (Energy Vault) | 4-12h | 200-400 USD/kWh | 75-80% |
V2G vehicles in Germany
| Vehicle | Battery | V2G power | Price |
|---|---|---|---|
| BMW iX3 (Neue Klasse) | 108 kWh | 11 kW | from EUR 63,400 |
| VW ID.3/4/5/7 (via Elli) | 52-86 kWh | TBD | from EUR 35,000 |
German BESS projects under construction
| Klostermansfeld (BW ESS) | 1,000 MW / 5,700 MWh | COD 2028 |
| LEAG GigaBattery Janschwalde | 1,000 MW / 4,000 MWh | planned |
| LEAG GigaBattery Boxberg | 400 MW / 1,600 MWh | 2026 |
| RWE Hambach | 236 MW / 470 MWh | COD 2027 |
Sources: CATL, Tesla, BYD, Fluence, Form Energy, Invinity, Hydrostor, BMW, VW, ESS News
This calculator uses PyPSA (Python for Power System Analysis), an open-source power system optimization framework. For each hour of the selected year, the model determines the least-cost dispatch of all available generation, storage, and import resources to meet electricity demand.
The optimizer minimizes total system cost by dispatching cheap renewables first, then batteries, imports, and finally backup power plants. Dunkelflaute hours are the hours where even after using all available renewables, batteries, imports, and V2G, the system still needs backup fossil/hydrogen power plants.
| Generation profiles | ENTSO-E Transparency Platform - actual hourly generation by source for Germany (DE-LU bidding zone), 2020-2024 |
| Load profiles | ENTSO-E - actual hourly electricity demand, 2020-2024 |
| Installed capacity | BNetzA Marktstammdatenregister, Fraunhofer ISE Energy Charts |
| EV statistics | Kraftfahrt-Bundesamt (KBA) - fleet size, registrations |
| Interconnectors | ENTSO-E TYNDP, BNetzA - total ~30 GW physical line capacity across 11 neighboring countries |
| Battery costs | BloombergNEF, IRENA, Fraunhofer ISE - 2025/2026 market data |
| Profile scaling | Historical generation profiles are normalized to installed capacity, then scaled to user-selected capacity. This assumes the same capacity factor distribution as the historical year. | |||||||||||||||||||||||||||||||||||||||
| Marginal costs | Renewables: 0.1 EUR/MWh (near-zero). Imports: 50 EUR/MWh. Backup plants: 100 EUR/MWh marginal + 1,000 EUR/MW capital cost. The optimizer dispatches cheapest sources first. | |||||||||||||||||||||||||||||||||||||||
| Short-duration BESS | Li-ion batteries (2-4h). Cyclic SOC. Standing loss: 0.01%/hour. Charge/discharge efficiency default 90%/100% (~90% RTE). | |||||||||||||||||||||||||||||||||||||||
| Long-duration storage | Iron-air / flow batteries (8h+). Modeled at ~42% round-trip efficiency (65% charge x 65% discharge), reflecting iron-air battery performance (Form Energy: 35-50% RTE). Lower RTE is acceptable because these charge from near-zero-cost curtailed RE and cycle infrequently (~25x/year). Standing loss: 0.005%/hour. | |||||||||||||||||||||||||||||||||||||||
| Imports | Modeled as a flat-capacity generator available at all hours. In reality, import capacity varies hourly with neighboring countries' own supply/demand balance. The user sets the assumed maximum. Default 21 GW = ~30 GW physical capacity minus ~30% for congestion, reliability margins, and the likelihood that neighbors also experience low RE during a Dunkelflaute.
Germany's cross-border interconnectors (~30 GW total)
Planned: NeuConnect (DE-UK, 1,400 MW, 2028), SuedLink/SuedOstLink (internal HVDC, 6,000 MW, 2027-28) will increase effective cross-border capacity by reducing internal congestion. Sources: ENTSO-E TYNDP, BNetzA, Clean Energy Wire. | |||||||||||||||||||||||||||||||||||||||
| V2G (Vehicle-to-Grid) | Modeled as a separate storage unit (V2G). Charge efficiency 88%, discharge 92%, standing loss 0.1%/h. Usable capacity = EV count × participation × battery size × usable share. Cyclic constraint applies. | |||||||||||||||||||||||||||||||||||||||
| Single node | Germany modeled as a single bus (copperplate). No internal grid congestion. In reality, north-south bottlenecks can create regional Dunkelflaute even with national surplus. | |||||||||||||||||||||||||||||||||||||||
| No demand response | Demand is treated as fixed (inelastic). Industrial demand response and smart EV charging (V1G) are not modeled. Both would reduce Dunkelflaute severity. |
| Parameter | Default | Reference (Germany) | Source |
|---|---|---|---|
| Annual load | 500 TWh | 466 TWh (2024) | SMARD/BNetzA |
| Solar PV | 215 GW | 99 GW (2024) | BNetzA MaStR |
| Wind onshore | 115 GW | 63.5 GW (2024) | BNetzA MaStR |
| Wind offshore | 30 GW | 9 GW (2024) | BNetzA MaStR |
| Battery storage | 25 GW / 4h | 3.4 GW / 5.7 GWh (H1 2026) | Modo Energy |
| Max import | 21 GW | ~30 GW total line capacity (all borders) | ENTSO-E TYNDP |
| BEV fleet | 2,000,000 | 2,034,260 (Jan 2026) | KBA |
| Total cars (DE) | 49,500,000 | 49,486,487 (Jan 2026) | KBA/Destatis |
| Avg BEV battery | 60 kWh | ~63 kWh (sales-weighted) | VW/Skoda/BMW specs |
| Battery system cost | 200 EUR/kWh | 165-240 EUR/kWh (installed, Europe) | BNEF, IRENA |
| Grid connection | 100 EUR/kW | 50,000-165,000 EUR/MW (BKZ, varies by region) | BNetzA |
This calculator is based on the ECO STOR Dunkelflaute model, extended with imports, V2G, cost estimation, and real ENTSO-E data. The optimization engine is PyPSA with the HiGHS solver. Source code: Backend | Frontend.
Energy data
Iron-air storage
Short-duration BESS
Other long-duration technologies
V2G and EVs
German BESS projects
Interconnectors
Last updated: September 2026. All prices and statistics are point-in-time and may have changed.