Battery Storage Model
Energy Financial Model (Free Excel Download)
Forecast battery dispatch, energy arbitrage, capacity revenue, ancillary services, degradation, augmentation capex, and project-finance returns.
professionals from Deloitte
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About this model
A battery storage project finance model projects revenues from wholesale energy arbitrage, ancillary grid services, and capacity market payments to determine whether a 100 MW / 400 MWh lithium-ion system can service non-recourse debt at 1.35x minimum DSCR and deliver 12%+ equity IRR. The model stacks three merchant revenue streams that vary with electricity price spreads, ancillary market saturation, and capacity auction dynamics, then stresses for power price compression and augmentation capex (new battery racks added mid-life to offset degradation).
Revenue modelling includes wholesale arbitrage (sold MWh at peak price minus charged MWh at off-peak price, both net of round-trip efficiency loss and grid fees), ancillary services (frequency regulation paid per MW per hour of grid service), and capacity market payments (bilateral contracts or auction clearing prices paid per MW per month). Opex is dominated by fixed long-term service agreement (LTSA) costs ($7.5M per MW per year), plus insurance, land lease, and asset management fees. Capex includes the EPC lump sum ($140M for a 400 MWh system at $350/kWh in 2025), grid connection, and a substantial interest-during-construction (IDC) charge capitalised to the asset. Augmentation capex is triggered when battery health of state (SOH) degrades below 80%, typically in year 13, requiring new racks at $200/kWh to restore capacity.
Infra PE sponsors, development equity investors, and lenders use battery storage models to assess project viability, stress revenue under different commodity price and capacity market scenarios, confirm DSCR adequacy including augmentation reserves, and compare projected equity IRR to the cost of capital for energy transition funds.
What every model includes
Live formulas, no hardcoded values
Outputs are driven by live formulas, so the workbook updates from its assumptions instead of relying on hardcoded results.
All assumptions in one tab
Inputs are clearly marked in the Assumptions tab and separated from calculations, making it clear what to change and what to leave intact.
Statements always balancing
For integrated-statement models, the balance sheet, cash flow, and supporting schedules tie through properly.
Distinct schedules for clarity
Debt, working capital, taxes, and cash flow can get messy quickly. We group calculations in clear schedules, not across disconnected tabs.
No hidden macros or external links
There are no unexplained external workbook links or macros to undermine auditability or portability.
Changes flow through the model
Update a key driver and see the impact carry through the forecast, financing, and return outputs. We never use hardcoded numbers in formulas.
What's inside the Battery Storage Model
- Revenue stacking across arbitrage, ancillary services, and capacity markets
- Battery degradation and augmentation capex schedules
- Round-trip efficiency and state of charge modelling
- Project finance debt structuring with DSCR and cash sweep logic
- IRR, NPV, and equity return outputs
- Battery system sizing: MW capacity and MWh duration
- Annual cycling volume and power price arbitrage revenue
- Ancillary services: frequency regulation, capacity provision, and other grid services
Battery Storage Model: What the BESS Project Finance Template Captures
This battery storage model is a project-finance template for evaluating whether a 100 MW / 400 MWh lithium-ion BESS can support non-recourse senior debt at a target DSCR of 1.35x and what equity IRR remains for the sponsor. It combines merchant revenue, operating costs, debt, tax and cash flow into one integrated structure.
Revenue Streams and Operating Drivers
The model stacks three merchant revenue streams. Wholesale energy arbitrage is the dominant line: imported MWh are driven by available capacity, annual cycles and availability, while exported MWh are reduced by round-trip efficiency.
- Arbitrage revenue nets charging cost inside the same line, so charging cost is not subtracted again downstream. Ancillary services are driven by power capacity, a per-MW hourly price, daily service hours, availability and days per year.
- Capacity market payments use derated MW, a monthly capacity price and twelve months. An RTM trading fee is charged as a percentage of arbitrage plus ancillary revenue but not on bilateral capacity payments, and the fee is netted inside the net revenue line.
Cost Structure and Tax Treatment
Operating costs are fixed and stored as positive numbers on the Opex sheet, which is the single source of truth for total operating expenses. Lines include fixed O&M under an LTSA, land lease, insurance based on total capex, asset management and property taxes.
- Most lines escalate at 2.5% inflation annually, with fixed O&M carrying a bundled LTSA escalator approximated at the same rate. Tax is applied at a flat 25% corporate rate, with 20-year straight-line tax depreciation on initial PP&E and a simple vintage-style treatment for augmentation capex.
- Net operating loss carry-forward is the default, so tax is charged only once cumulative taxable profit turns positive. No MACRS, ITC or PTC is included in the base case.
Debt, Capital Structure and Calculation Flow
The model is sized at 55% debt and 45% equity with an 18-year tenor and straight-line principal amortisation, not DSCR-sculpted. Interest accrues on the opening debt balance at a 6.5% all-in rate.
- Interest during construction is calculated on the debt portion of hard capex using the drawdown profile and an average outstanding percentage of 0.90 for a 40/60 two-year draw, then capitalised into PP&E; the facility is grossed up so the bank pays the IDC. A DSRA equal to six months of forward debt service is funded from debt proceeds at COD and released at final maturity.
- The straight-line amortisation choice breaks the tax-interest-debt circularity because debt service is known without reference to CFADS. The build order runs from assumptions through technical build, revenue, opex, capex, debt, financials, tax, waterfall and returns.
Outputs and Practical Use
The outputs include project IRR, equity IRR, NPV, minimum DSCR and LLCR, supported by checks covering balance sheet balance, positive cash, declining debt, minimum DSCR, positive distributions and valid IRR signs. EBITDA is defined once on the Financials sheet from net revenue less total opex and consumed by tax, DSCR and waterfall calculations, avoiding duplicate definitions.
- CFADS converts from EBITDA at roughly 90%, with the gap representing cash taxes and working capital movements. Debt service is subtracted, DSRA movements are applied, and positive distributions flow to equity.
- The model is intended for sponsor-side FID decisions and lender-side credit review, and the public download is a values-only preview rather than a live formula workbook.
Formatted to IB standards
Named theme colors repaint the whole workbook in one click, on top of an investment-banking structure with clear input, output, and cross-sheet reference styling - brand-ready, institutional-grade, and fully auditable.
Created by ex-finance professionals
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Frequently asked
What is a battery storage financial model?+
It is a model that forecasts the revenue, costs, and returns of a battery energy storage system across its operational lifecycle.
Who uses BESS financial models?+
Infrastructure investors, renewable energy developers, project finance bankers, and asset managers use them to underwrite storage investments.
What should a battery storage model include?+
It should include revenue stacking, degradation schedules, augmentation capex, round-trip efficiency, and debt structuring with coverage ratios.
How does degradation affect the model?+
Battery capacity declines over time, which reduces revenue potential. The model tracks this and includes augmentation capex to maintain nameplate capacity.
Can it handle multiple revenue streams?+
Yes. The model supports simultaneous revenue from energy arbitrage, capacity markets, and ancillary services such as frequency response.
Have more financial modelling questions? Contact us
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