The Battery Storage
Availability Put.

A contractual floor on availability. We guarantee uptime, so lenders underwrite, investors model, and developers close — without holding the operating risk themselves.

The Put
The Platform

We've built systems across technology and finance

01

How the Put works.

Three steps from eligibility review to monthly cash settlement.

STEP 01
Assess
Asset eligibility review: chemistry, OEM, site, interconnection. 2-week diligence.
STEP 02
Strike
Contract sets availability floor (e.g. 97%). Premium sized by risk model.
STEP 03
Settle
Monthly attestation. Shortfalls paid in cash to the borrower or project LLC.
02

The problem.

Battery storage is under-leveraged. Operating risk is sitting in the equity check.

  • Banks offer less debt — the cheapest capital — because availability and dispatch risk aren't underwritable today.
  • Sponsors are forced to commit more equity, the most expensive layer in the capital stack, to absorb that gap.
Battery storage
55%
Solar
70%
Aircraft leases
81%
Student loans
84%
Equipment loans
89%
Auto loans
92%
Home mortgages
99%
Advance rate by asset class. Source: S&P, Fitch, Kroll, Moody's, Marathon Capital.
03

The solution.

A contractual availability floor that banks can underwrite against.

  • Investment-grade insurers backstop availability shortfalls on the asset.
  • Banks get comfortable lending more against credit-enhanced cash flows — moving BESS closer to the advance rates the rest of project finance already enjoys.
Telemetry
+
Engineering
+
Insurer
→
Lower risk · Lower cost · More storage
04

Before & after.

Where the Put sits in the capital stack — and what it changes for both sides of the table.

Before
Sponsorwants more debt
⇄
BESS assetuninsured operating risk
⇄
Bankwants to lend safely
After — with the Availability Put
Sponsor
→
Availability Put
Backed by investment-grade insurers
←
Bank
Sponsor gets
  • Better debt terms
  • Lower cost of capital
  • Less equity needed per project
  • Higher equity IRR
  • Product pays for itself
Bank gets
  • Credit enhancement backed by insurer
  • Lends more, with confidence
  • Wins more deals against other banks
Cost of capital is the biggest single line item on a battery project. Tightening it reshapes which projects get built — and who builds them.

Understands your battery fleet

1
Connects to your SCADA, BMS, and historian systems. Cell-level telemetry streaming in minutes, not months of custom integration.
2
Builds a real-time model of every rack, module, and cell. Tracks thermal profiles, SOC curves, and degradation trajectories across your fleet.
3
Ingests maintenance logs, OEM bulletins, warranty terms, and field team knowledge into a unified context layer.
SCADA + BMS integration
real-time fleet model
knowledge base ingestion

Reasons like a seasoned field engineer

1
When a fault surfaces, it investigates thermal runaway risk, cell imbalance, BOP failure, and grid-side issues simultaneously — not sequentially.
2
Orchestrates evidence collection across BMS telemetry, SCADA alarms, weather feeds, and dispatch logs to triangulate root cause.
3
Builds causal timelines linking thermal events, SOC anomalies, inverter faults, and capacity fade into a single diagnostic narrative.
parallel hypothesis investigation
cross-system evidence collection
causal timeline view

Operates your tools like an expert

1
Auto-generates work orders in your CMMS, assigns field technicians, and tracks resolution — closing the loop from detection to repair.
2
Navigates Modbus, DNP3, OPC-UA, and OEM-specific APIs without requiring protocol specialists on every call.
3
Coordinates cross-domain investigations spanning electrical, thermal, controls, and commercial systems in a single triage workflow.
automated work order generation
multi-protocol navigation
cross-domain triage workflow
The platform behind the put

The guarantee is only as good as the tools that improve it.

Behind the Put sits our platform: custom sensors, SCADA integration, and CMMS automation that lets us monitor and accelerate triage interventions.

Battery storage is the backbone of the energy transition.

Every grid that integrates renewables depends on it — it's how electricity stays reliable when the sun sets and the wind dies. Battery energy storage is being built faster than any other category of grid infrastructure, and lenders are being asked to finance trillions of dollars of it over the next decade.

The people who actually make that financing possible are insurers. No bank lends against a battery without insurance behind it. No toll gets signed, no tax credit gets monetized, no project reaches financial close without coverage that lenders can underwrite against. Insurance is the load-bearing layer beneath the entire asset class — and right now, it isn't built for the risks that matter most. Lenders are sizing debt off availability assumptions that operating data is starting to challenge. Operators are absorbing revenue leakage that standard policies don't address. The risks that shape a battery's economics over a decade — degradation, dispatch, OEM concentration, operational variance — sit in a gap the insurance industry hasn't filled.

Millennium Energy is building engineering-grade insurance for battery energy storage. Our team comes from the asset side, not the paperwork side. We integrate directly with operating data, underwrite based on what the asset actually is rather than industry averages, and structure coverage that addresses the operational risks lenders and operators are really carrying. We work hard, move fast, and obsess over the technical details that traditional underwriters can't see. We help finance the energy transition, one battery at a time.

BESS Revenue Put — what's it worth?

A revenue floor lets banks lend more against a battery project. Here's how much equity that frees up for the developer.

How big is your project? Bigger projects = bigger absolute savings $50M
$20M$40M$60M$80M
How locked-in is the project's revenue? More contracts = banks already comfortable Partial — some contracts, some merchant
Mostly merchantPartialMostly contracted
With the revenue put in place, the developer needs
—
— less of their own cash for this project.
That's cash they can deploy into the next one.
Bank lends more
—
—
Cost of capital drops
—
—

Where the money comes from

Without revenue put — bank lends conservatively —
—
—
With revenue put — bank gets credit enhancement, lends more —
—
—

For the analysts in the room

All assumptions exposed and adjustable. Pre-filled from the sliders above — tweak anything to model your specific deal.

Project

Revenue (P50)

Without Put

With Revenue Put

Macro

Metric
Without Put
With Put
Project
—
—
Total capex
—
—
Annual P50 revenue
—
—
Annual NOI
—
—
Financing
—
—
All-in debt rate
—
—
Debt tenor
—
—
Debt size
—
—
Effective advance rate
—
—
Binding constraint
—
—
Equity required
—
—
Annual debt service
—
—
Annual put premium
—
—
Returns
—
—
Yr 1 cash flow to equity
—
—
Equity IRR
—
—
WACC (post-tax, simplified)
—
—

Cash Flow to Equity

Annual cash to sponsor after debt service & put premium
Without Put
With Put

Cumulative Equity Returns

Running total of cash returned to equity, starting from initial check
Without Put
With Put
Methodology & assumptions

Debt sizing. Debt size = min of (a) DSCR-constrained — annual NOI / DSCR, capitalized as an annuity at the all-in debt rate over the tenor; (b) advance-rate-constrained — capex x max LTC. Whichever binds determines the debt amount.

NOI. Annual revenue x (1 - opex %). Revenue assumed flat across project life (no escalation, no degradation). Opex captured as % of revenue.

Equity IRR. Levered cash flow to equity over project life. Year 0 = equity check. Years 1 through debt tenor: NOI - debt service - put premium. Years after debt tenor: NOI. Solved by bisection. No terminal value.

Why doesn't IRR move much? For most BESS deals, both scenarios are DSCR-bound. The put unlocks more debt, but that debt comes with more annual debt service that offsets the smaller equity check. The value lives in capital efficiency (less equity per project = more projects per fund) and weighted cost of capital, not in equity IRR.

What's omitted. Capacity degradation and augmentation capex; ITC / transferable tax credits; tax equity structuring; revenue/opex escalation; merchant tail risk modeled separately. These affect absolute returns but affect both scenarios roughly equally.