Battery Storage Investment Calculator — Germany · Sources
Sources of the German battery storage model
The model rests on 47 public sources. Each entry shows the date it was checked or published and what the model takes from it. Where no current public value exists, the input is a documented assumption — listed at the end. How the inputs are used is described in the methodology.
Price data
The revenue rests on the day-ahead prices of the German–Luxembourg bidding zone published by the Bundesnetzagentur on SMARD.de and served by Energy-Charts (Fraunhofer ISE) under CC BY 4.0, up to 30 Sep 2026. Since 1 October 2025 the day-ahead market trades quarter-hours; the model averages them to hours so that both price years compare. The site does not republish the price series: it shows only results derived from it — the precomputed revenue library and the price statistics on the Revenue tab.
Prices
- Energy-Charts (Fraunhofer ISE): DE-LU day-ahead prices, data Bundesnetzagentur | SMARD.de (CC BY 4.0)3 Oct 2026 · Day-ahead prices of 2025 (the base snapshot) and of October 2025 to September 2026 (the alternative), retrieved through the Energy-Charts API, with the quarter-hours averaged to hours from 1 October 2025: the input of the revenue library. The daily spreads between the two highest and two lowest hours sum to €84,737.51 per MW for 2025 and €97,716.57 for the alternative; January–September 2026 ran 18.5% above the same months of 2025, the 2028 level of the high spread path. Inputs: Price year.
- EPEX SPOT: 15-minute products in the day-ahead market coupling3 Oct 2026 · Day-ahead prices come in quarter-hours from delivery on 1 October 2025, so the model averages each hour’s four quarter-hours and compares all prices by the hour. In January–September 2026 the quarter-hours gave a spread 4.8% wider than their hourly averages; the model leaves that gain out.
Revenue: tolling and trading
- Modo Energy: June 2026 German battery storage livestream, key takeaways3 Oct 2026 · In an extreme case of 78 GW of batteries, the spread between the highest and lowest prices narrows by about 40%: the floor of the low spread path, 60% of the snapshot spread from 2031 after 85%, 75% and 65% in 2028–2030. Inputs: Spread path.
- Fraunhofer ISE: Energy-Charts launches a price simulator (press release, 1 Oct 2026)3 Oct 2026 · Adding 20 GW / 40 GWh of batteries to the 2025 bids cuts the average spread between the highest and lowest quarter-hour prices from €130 to €53 per MWh, about 60%: a static test that goes further than the low spread path. Inputs: Spread path.
- Hornek et al., arXiv preprint: battery storage in the continuous intraday market, forecast vs perfect foresight (Jan 2025)3 Oct 2026 · On the continuous intraday market a forecast-driven strategy earned 11% less than perfect foresight. No study calibrates day-ahead trading alone in Germany, so the capture factor — 75% of the perfect-foresight day-ahead margin, 65% and 85% in the tornado — is an assumption. Inputs: Realism factor.
- enspired: BESS revenue models — toll, floor and fully merchant (4 Feb 2025)3 Oct 2026 · Revenue splits between owner and optimiser of 90:10, 85:15 and 80:20: the model’s fee of 10% of the positive merchant margin after the capture factor, with no fee on the tolled share. Inputs: Optimiser’s fee.
- Terralayr: what are tolling agreements? (15 Oct 2025)3 Oct 2026 · Indicative tolls of €110,000–150,000 per MW a year, typically for five to seven years and sometimes ten: the market range shown next to the break-even toll, the base toll of €120,000 for two hours and €110,000 in the tornado. The €150,000 for four hours has no public German deal behind it. Inputs: Toll price.
- Nofar Energy: Tel Aviv Stock Exchange filing on the Stendal battery toll, 104.5 MW / 209 MWh (8 Dec 2024, in Hebrew)3 Oct 2026 · A seven-year toll for a fixed €85–95 million, paid monthly and adjusted for performance and availability (about €116,200–129,870 per MW a year): the 84-month term, the nominal fee linked to availability (95% guaranteed in the model) and a cross-check of the toll price. The tolled share is not disclosed; the model’s 80% is an assumption. Inputs: Tolling contract; Toll price; Contracted share; Contract term.
- StromVKG (capacity market law of 21 Jul 2026) §12: eligibility in the 2026 auctions3 Oct 2026 · A battery in the 2026 capacity auctions must deliver for ten hours at 80% or more of its installed power, which two- and four-hour batteries cannot do: one reason the model counts no capacity-market revenue.
Technology
- NREL BLAST-Lite battery degradation models (BSD-3)3 Oct 2026 · Calendar and cycle fade of an LFP cell: 1.1% × years^0.526 and 1.55·10⁻⁴ × EFC^0.828, with the exponents of the BLAST code and the coefficients reduced to fixed values at 25 °C; the stress case raises fade by 30%. Inputs: Faster wear.
- ESS News: Making BESS warranties work — contracts vs reality (Sep 2025)3 Oct 2026 · A manufacturer warranty of about 548 cycles a year at 0.5C: the cap of 1.5 cycles a day (1.0 as a variant), which is also the toll buyer’s daily cycling. Inputs: Cycle limit.
- enervis in pv magazine: German battery storage revenue index for July 2026 (28 Aug 2026)3 Oct 2026 · Index inputs of 97% availability, 1.5 cycles a day and 87% round-trip efficiency: the model’s 97% availability after the first operating year, its cap of 1.5 cycles a day and its efficiency nodes of 85–90%. Inputs: Round-trip efficiency; Availability.
- Solarif: what performance guarantees lenders require for BESS3 Oct 2026 · Lenders require availability guarantees of 95–98%: the model’s 95% availability in the first operating year and the 95% availability guaranteed to the toll buyer. Inputs: Availability; Availability, first year.
Investment and operating costs
- Modo Energy: Germany battery investment outlook Q2 2026, executive summary (16 Mar 2026)3 Oct 2026 · All-in costs of €700 per kW for two-hour and €935 per kW for four-hour batteries commissioned in 2026: shown next to the model’s €765 and €1,024 per kW, without fitting. In the same outlook, 50% more batteries cut day-ahead spreads by 17% in 2030: an anchor of the low spread path. Inputs: Spread path; Investment cost; Development cost.
- SolarPower Europe: European Battery Market Outlook 2026–2030 (23 Jun 2026)3 Oct 2026 · DC containers at €64–77 per nameplate kWh in Q2 2026: the DC block at €75 per kWh (€177.67 per kW at two hours) and the augmentation of 15% more DC capacity in February 2038 at €86 per kWh, module plus 15% installation. Inputs: Investment cost.
- Ember: How cheap is battery storage? (11 Dec 2025)3 Oct 2026 · Installation and grid connection at about $50 per kWh outside China and the US: the cross-check for balance of plant and EPC at €100 per kW for two hours and €150 for four. Inputs: Investment cost.
- Lazard: Levelized Cost of Energy+ 2026, storage (LCOS v11)3 Oct 2026 · Operation and maintenance at USD 5.00–8.75 per kWh a year for two-hour and USD 3.75–7.75 for four-hour systems: the cross-check for O&M of €10,000 and €16,000 per MW a year. Round-trip efficiency of 87–91% at two hours: the efficiency nodes of 88% and 90%. Inputs: Round-trip efficiency; Operation and maintenance.
- Solarif: emerging trends in battery storage insurance3 Oct 2026 · Broker guidance of 0.3–1.2% of the insured value a year: the model’s 0.5% a year on the cost of the DC block, PCS, balance of plant, substation and contingency (€23.5 million at two hours in 2026 prices), indexed. Inputs: Insurance.
- ENLAPA: leasing land for large battery storage3 Oct 2026 · Leases of €20,000–30,000 per hectare a year: the model’s €25,000 per hectare on 1 ha (two hours) or 1.5 ha (four hours).
- EU Battery Regulation 2023/1542, Article 61: collection of waste industrial batteries (text at Haufe)3 Oct 2026 · Producers take back waste industrial batteries free of charge: the model’s net decommissioning cost of €10 per kWh of initial usable capacity (dismantling, transport and site restoration less scrap), paid in April 2043.
Grid fees and charges
- Bundesnetzagentur: draft AgNes determination on network charges for generators and storage (GBK-25-01-1#3, 6 Aug 2026)3 Oct 2026 · A capacity fee on contracted connection capacity from 1 January 2029, with illustrative values of €4.92–5.14 per kW a year: the model charges €5,000 per MW on all 50 MW (2029 money, indexed from 2030; €0 and €7,000 in the tornado). Projects whose investment decision comes before the determination is announced, planned for 1 January 2027, would keep the exemption; dynamic fees for 2030–2033 are not modelled. Inputs: AgNes capacity fee.
- Energy Industry Act (EnWG) §118(6): network-charge exemption for storage3 Oct 2026 · Storage commissioned by 4 August 2029 pays no network charges on the electricity it stores and feeds back for 20 years: the grandfathering switch, off in the base case and void if commissioning slips past that date. Inputs: Grid-fee exemption.
- Bundesnetzagentur: storage FAQ, construction-cost contributions after the Federal Court of Justice ruling of 15 Jul 2025 (EnVR 1/24)3 Oct 2026 · A grid-connected battery pays a construction-cost contribution on its import capacity, with no automatic exemption: the model charges €135 per kW (€6.75 million for 50 MW), between the published 2026 prices of €91 and €163 per kW, with €0 and €165 in the tornado. Inputs: Grid connection contribution (BKZ).
- Netze BW: construction-cost contribution price sheet, electricity (from 1 Jan 2026)3 Oct 2026 · €162.97 per kW at 110 kV: the top of the published 2026 prices around the model’s €135 per kW. Inputs: Grid connection contribution (BKZ).
- TransnetBW: network charges and construction-cost contribution 2026 (price sheet of 5 Dec 2025)3 Oct 2026 · Contributions of €96.91 per kW at extra-high voltage and €113.15 at the extra-high/high-voltage transformation, times a regional factor of 0.8–1.0, paid 50% at contract, 30% when grid works start and 20% at grid commissioning: the lower published prices and the model’s payments in months 1, 3 and 12. Metering at €3,533.84 per point a year: €3,500 in the model. Inputs: Grid connection contribution (BKZ).
- Electricity Tax Act (StromStG) §5(4): storage as part of the supply network3 Oct 2026 · No electricity tax on charging when the battery meets the conditions to count as part of the supply network: the model’s tax on charging is zero.
- Energy Financing Act (EnFG) §21: levies on electricity storage3 Oct 2026 · No KWKG, offshore-grid or §19 StromNEV levies on electricity that is stored and fed back, counted over the year: the model’s levies on charging are zero.
- Electricity Tax Act (StromStG) §3: standard tax rate3 Oct 2026 · The standard electricity tax of €20.50 per MWh, which the model applies to auxiliary consumption: with the levies and the network charge on about 1,400 MWh a year, it charges €2,000 per MW a year in 2026 prices, indexed. Inputs: Charges on own consumption.
Financing
- Modo Energy: toll agreements, leverage and equity returns in Germany (30 Jan 2026)3 Oct 2026 · Toll-backed debt is sized over 15–20 years but falls due after seven, with at least 60% repaid and the rest refinanced, at an all-in 4–6%: the model’s 5.60% sits in that range, and its fully amortising ten-year loan simplifies this mini-perm. Inputs: Bank loan; Interest rate; Loan term; Cover on the toll; Cover on the market; Maximum debt share.
- ESS News: how financing of standalone and co-located batteries really works, BBDF 2026 (1 Apr 2026)3 Oct 2026 · Commerzbank’s debt-sizing ratios of 1.15 on contracted and 2.0 on merchant cash flow: the model’s target DSCRs, applied in its bank case. Inputs: Cover on the toll; Cover on the market.
- ZfK: battery storage financing by marketing model (15 Jul 2026)3 Oct 2026 · Debt of 70% with a five-year toll and 60% for a partly financed merchant model (Capcora, suena): the market reference for the model’s debt cap of 80% of uses with an 80% toll for seven years. Inputs: Maximum debt share.
- UmweltBank: financing of the Halle (Saale) battery, 11 MW / 22 MWh3 Oct 2026 · A ten-year loan for a fully merchant battery without toll or floor: the same term as the model’s loan. Inputs: Loan term.
Tax
- Trade Tax Act (GewStG): current consolidated text3 Oct 2026 · Trade tax of 3.5% of trade income times the municipal multiplier, 400% for the fictional municipality (legal minimum 200% to 2026 and 280% from 2027); 25% of interest plus half the property rent, above €200,000, added back; losses offset €1 million in full and 60% beyond; prepayments on 15 February, May, August and November. Inputs: Trade-tax multiplier (Hebesatz).
- Corporation Tax Act (KStG) §23: tax rate3 Oct 2026 · Corporation tax of 15% to 2027, then 14%, 13%, 12% and 11% in 2028–2031 and 10% from 2032.
- Solidarity Surcharge Act (SolzG) §4: rate3 Oct 2026 · Solidarity surcharge of 5.5% of the corporation tax.
- Income Tax Act (EStG) §10d: loss deduction3 Oct 2026 · Corporation-tax losses carried forward offset the first €1 million of income in full and 70% of the income above it in 2024–2027; the model carries no losses back.
- Growth Opportunities Act of 27 Mar 2024 (BGBl. 2024 I Nr. 108), Article 6: loss deduction from 2028 (text at buzer.de)3 Oct 2026 · From 2028 corporation-tax losses offset 60% instead of 70% of the income above €1 million.
- Income Tax Act (EStG) §4h: interest barrier3 Oct 2026 · Net interest below €3 million a year is exempt from the interest barrier; at €3 million or more the model flags its tax as incomplete (about €0.9 million in the base case’s largest year).
- Federal Ministry of Finance: depreciation (AfA) table for energy and water supply (24 Jan 1995)3 Oct 2026 · Accumulators over 15 years, the base tax life of the battery and its augmentation, and converters over 20 years, the life of the PCS. Inputs: Battery tax life.
- Federal Ministry of Finance: depreciation (AfA) table for general fixed assets (15 Dec 2000)3 Oct 2026 · Ten years under item 3.1.3: a disputed alternative for the battery of a storage-only company, offered as a switch and a tornado case. Inputs: Battery tax life.
- Income Tax Act (EStG) §7: depreciation3 Oct 2026 · Straight-line depreciation from the month of commissioning, 11/12 of a year in 2028. Declining-balance depreciation is open only to assets acquired or made from 1 July 2025 to 31 December 2027, which a February 2028 battery does not show, so the model leaves it out.
- VAT Act (UStG) §12: tax rates3 Oct 2026 · VAT of 19% on the investment, the augmentation and the PCS overhaul, refunded two months after payment in the model; VAT on the toll invoices has no cash effect.
Interest rates and inflation
- BlueGamma: EURIBOR swap rates (1–2 Oct 2026)3 Oct 2026 · A 10-year euro swap at 3.64% on 1 October and 3.59% on 2 October 2026 (vendor mid-rates): with a 2.00% margin, the fixed all-in loan rate of 5.60%. Inputs: Interest rate.
- Deutsche Bundesbank: projection for Germany, Monthly Report June 20263 Oct 2026 · German HICP inflation of 2.9% in 2026, 2.7% in 2027 and 1.9% in 2028, extended at 2.0% a year from 2029: the index that turns 2025 market prices and 2026 costs into nominal euros.
Company and insolvency law
- Limited Liability Companies Act (GmbHG) §30: capital maintenance3 Oct 2026 · Distributions never take net assets below the €25,000 share capital.
- Insolvency Code (InsO) §15b: payments to shareholders, with §18: imminent illiquidity3 Oct 2026 · Distributions also never spend cash the company’s plan still needs until the end of the case — an assumption of the model that goes beyond the ban on payments to shareholders that must lead to illiquidity (§15b(5) InsO), which prescribes no formula. The 24-month forecast of §18(2) InsO concerns imminent illiquidity, not this rule.
- Limited Liability Companies Act (GmbHG) §73: distribution after liquidation3 Oct 2026 · The cash left after liquidation is paid on 30 April 2044, a year after the creditors are called on (Sperrjahr).
Assumptions
These inputs have no current public value that fits the case. The base case uses a documented assumption, often next to a public reference point; the sensitivity and the alternative cases show how much each one matters.
Spread path; Spread multiplier; Realism factor; Duration; Availability, first year; Delay to commercial operation; Development cost; Company costs; Equity hurdle rate; Project discount rate.