Sponsor Case, Financing Base Case and Downside Cases: Bridge the Assumptions, Not the Labels
The worked example starts with two deliberately different assumption sets for the same project and produces debt capacities $53.8m apart. Call them the Sponsor Case and the Lender Sizing Case for this article; the executed financing may use different labels.
Sponsor Case CFADS $30.0m → coverage capacity $240,749,224
Lender Sizing Case CFADS $23.3m → coverage capacity $186,988,855
Something else changes between the two worked cases: the Sponsor Case cash yield on cost is 11.05%, which places it above the worked gearing / coverage crossover, while the Lender Sizing Case is 8.58% and falls below it. The binding constraint therefore changes between the two cases.
This final post covers how to define the model cases, bridge the assumptions between them, build coherent downside cases and identify when the binding debt constraint changes.
ℹ️ Note: The haircuts below are labelled assumptions assembled from the preceding series. Real lender cases vary; the structure of the bridge is what generalises.
What Are the Cases?
Do not infer ownership or conservatism from the label.
Public credit agreements use Base Case Model in different ways. A filed portfolio facility defines its Base Case Model using P50 Production, eligible revenues and operating expenses. A 2026 DOE-supported financing requires a certified Execution Date Base Case Financial Model, a CFO variance explanation and Financial Advisor / Independent Engineer confirmation of mathematical accuracy, consistency and reasonableness. Another 2026 facility requires an updated Base Case Model satisfactory to Required Lenders and certified by the Independent Engineer for technical, operating and construction assumptions.
For this article, use three functional categories:
| Case | Purpose | Typical owner / approver |
|---|---|---|
| Sponsor investment case | sponsor's expected economics and valuation | sponsor / investment committee |
| Financing base / lender sizing case | debt sizing and finance-document calculations | defined / approved under the credit process |
| Downside cases | test specific adverse states and covenant / liquidity resilience | sponsor, lenders and advisers depending on the risk |
The names can change. The important thing is which inputs, approvals and consequences attach to each case.
The Sponsor Investment Case
The sponsor investment case should represent the sponsor's central underwriting view under a documented set of assumptions. That can include a central energy estimate, price case, expected availability and operating costs, but none of those inputs is universally prescribed.
Its purpose is to value the project and to set the equity return. It is the case an investment committee approves and the case a farm-down is priced against.
If the sponsor deliberately includes prudence in this case, label it. The important discipline is that the investment committee can distinguish expected assumptions from explicit downside or valuation cushions.
The Financing Base Case, and the Bridge to It
For the worked example, the Lender Sizing Case applies four explicit changes to the Sponsor Case. This is an illustration of a bridge, not a claim that every lender case is created by the same four haircuts.
| Revenue | Change | |
|---|---|---|
| Sponsor base case | $33,000,000 | |
| Worked generation haircut | $30,393,000 | ($2,607,000) |
| Curtailment, node-specific at 4% | $29,177,280 | ($1,215,720) |
| Basis and capture rate | $26,843,098 | ($2,334,182) |
| Availability at 97% against 99% assumed | $26,300,867 | ($542,231) |
| Lender Sizing Case | $26,300,867 | −20.3% |
Then the operating leverage effect from the merchant tail post, because costs do not fall with revenue:
Base case CFADS $33.0m − $3.0m opex = $30,000,000
Lender sizing CFADS $26.3m − $3.0m opex = $23,300,867
-----------
Reduction 22.3%
Revenue falls 20.3% and CFADS falls 22.3% — the two-point amplification that follows automatically from a fixed cost base, and which is why every haircut in this series lands harder than it looks.
And the debt capacity that follows, at a 1.30× coverage target over eighteen years:
Base case debt capacity $240,749,224
Lender sizing coverage capacity $186,988,855
-----------
Difference $53,760,369
What Else Can Differ in the Financing Base Case?
The financing model can differ from the sponsor case on any assumption the credit process or finance documents define. The following are diligence categories, not automatic lender adjustments.
Operating cost escalation. Compare the sponsor assumption with the technical adviser, O&M contract, insurance, land and inflation inputs used in the financing model.
Maintenance capex and major overhauls. The CFADS and reserve definitions determine how these items affect debt sizing. Reconcile the financial model to those definitions.
Tax. The depreciation post's point applies: a project with accelerated depreciation has a cash tax profile that is nothing like a straight line, and a lender sizing on post-tax CFADS needs the actual profile rather than a normalised rate.
Inflation on revenue versus cost. A PPA with a fixed price or a sub-inflation escalator against an opex base escalating at CPI produces a declining real margin. That is a genuine feature of the contract and it only appears in a nominal model, which is why the cost of capital post argued for building nominally.
The merchant tail. Financing assumptions can change price, volume, tenor credited, DSCR or other sizing inputs for uncontracted periods. Use the term sheet / credit agreement rather than a generic merchant-tail haircut.
Refinancing assumptions. Where the structure has a mini-perm, the lender's case will not assume a refinancing at the same terms. It will size the wall and test whether a stressed market clears it.
The practical consequence is that the financing base case should be reconciled across all affected inputs, not treated as the sponsor model with one lower price curve. The revenue haircuts are the ones that get discussed; the cost, tax and escalation adjustments are the ones that arrive quietly and, in aggregate, frequently exceed them.
The Regime Change Nobody Notices
Here is the part worth taking away from this post.
Base case CFADS ÷ project cost = 30.0 / 271.5 = 11.05%
Lender sizing CFADS ÷ project cost = 23.3 / 271.5 = 8.58%
Crossover (75% gearing, 1.30×, 6.5%, 18 years) = 9.35%
In the worked Sponsor Case, gearing binds and limits debt to $203.6m even though the coverage formula would allow $240.7m. In the worked Lender Sizing Case, coverage binds at $187.0m.
That means the two parties are, without realising it, having two different conversations.
This is why the model should publish the binding constraint beside each debt number. A term-sheet discussion about gearing is irrelevant when coverage binds; a debate about a small revenue assumption may be irrelevant if the gearing cap still controls. Publishing the binding constraint alongside the debt number — as the first project-finance mechanics post argued — resolves it in a line, and it is almost never done.
Sensitivities Are Not Scenarios
A distinction that determines whether downside analysis is useful.
A sensitivity moves one variable and holds everything else. It answers "how much does this input matter" and is the right tool for identifying which assumptions drive the answer.
A scenario moves a coherent set of variables in a way that could actually happen together. It answers "what does this state of the world do to us."
Most models produce many sensitivities and no scenarios, which leaves two errors uncorrected.
Independent sensitivities can understate correlated risk. As the yield post established, resource and curtailment are correlated, and as the Market Structure analysis showed, basis and capture rate and negative pricing all move together because they share a cause. Running each as a separate sensitivity and reporting the worst individually understates what happens when the underlying driver moves.
Independent haircuts also overstate uncorrelated risk. Stacking a P99 resource year on top of a P99 price year on top of a P99 availability year produces a number with a probability so small it carries no information, and it crowds out the scenarios that matter.
The useful downside set is small and coherent:
Low resource + high curtailment (correlated driver: regional build-out)
Merchant prices low + basis wide (correlated driver: local oversupply)
Delay + cost overrun (correlated driver: contractor stress)
Offtaker downgrade + refinancing (correlated driver: credit cycle)
Four scenarios that describe recognisable states of the world beat twenty sensitivities that describe none.
Break-Evens Beat Both
The most useful downside output is not a case at all. It is the point at which the structure stops working.
The Project Finance Mechanics and Returns & Valuation posts produced several:
- The basis at which the lock-up covenant breaks — −$3.68/MWh on the worked project
- The accreditation at which capacity revenue stops mattering to the credit
- The CFADS at which leverage starts reducing the equity return
- The step-up in network upgrade costs that triggers the withdrawal exemption — 25%
- The contingency confidence level implied by what is carried
- The crossover CFADS between gearing and coverage constraints — 9.35% yield on cost
A break-even survives a forecast being wrong. A scenario does not: it is a specific set of numbers whose probability nobody can state, and it goes out of date the moment an assumption changes. A break-even says how much room there is, which is the question a credit committee is actually trying to answer and the one a base case cannot address.
If a model produces only one thing beyond the base case, it should produce break-evens.
Who Owns Which Case?
Governance matters here more than it sounds, because a case with no owner drifts.
Assign an explicit owner and approval path to every case. The sponsor can own its investment case. The financing Base Case Model may be borrower-prepared but subject to agent / lender approval and Independent Engineer certification. Technical downside assumptions can come from the IE; market, tax or insurance cases may come from other advisers.
The reconciliation also needs an owner. Without one, two internally consistent models can drift apart without a controlled bridge. The bridge in this post — four lines adding to $53.8m of coverage-based debt capacity — illustrates how to convert a disagreement about a headline number into a discussion about identifiable assumptions.
Who Verifies the Model?
Different advisers verify different things, and the engagement scopes matter.
Model auditor / model reviewer. Commonly checks formulas, logic, circularity, debt sculpting, covenant calculations, cash-waterfall implementation and consistency with transaction documents. Whether it comments on assumptions depends on the engagement scope.
Independent Engineer / technical adviser. Can review energy yield, availability, capex, opex, construction schedule and the reasonableness of technical assumptions. Public project-finance documents often require IE certification of model assumptions or project budgets.
Market, insurance and tax advisers. Support their own assumption sets within their mandates.
The financing case should therefore carry an assumption-source map:
Generation / degradation → technical adviser / IE
Merchant price / basis → market adviser or agreed curve
Insurance costs / proceeds → insurance adviser
Tax credit / depreciation → tax adviser
Debt mechanics → finance documents / model audit
The key governance point is not that one party is “conservative.” It is that every material financing assumption should have a named owner, source and update process.
When the Case Moves Mid-Deal
A financing case is not frozen merely because the term sheet was signed.
Between term sheet and closing, yield, capex, interconnection, pricing, rates, hedge costs or completion assumptions can move. If the debt-sizing model is updated, the debt amount can move with it.
On the worked example, the gap between the Sponsor Case and Lender Sizing Case is $53.8m. A smaller mid-deal change can still translate into a material incremental equity requirement.
Three disciplines help:
Document the indicative sizing assumptions. State the energy basis, price curve, cost estimate, rate and key ratios used in the term sheet / credit paper.
Understand model-update and flex provisions. The financing documents may permit updated Base Case Models, lender review, technical-adviser certification or syndication flex. Those are contractual mechanisms, not surprises.
Pre-model the equity sensitivity. Show how much incremental sponsor capital is needed for changes in revenue, capex, rates or sizing ratios before the deal reaches credit committee.
The broader point is simple: a financing amount generated from a case that can still move is a conditional number until the closing conditions and model are fixed.
How Do You Build This in Excel?
As one model with a case switch, and an explicit bridge between cases.
The case switch
Case_Selector: 1 = Base 2 = Banking 3 = Downside_A ...
Every haircut input reads from a case table:
Generation_Basis sponsor / financing / downside energy case
Curtailment_Rate base / lender / stress
Basis_$/MWh base / lender / stress
Availability contractual / lender / stress
Never build separate workbooks per case. Separate files diverge, and the divergence is discovered at the worst moment.
The bridge, which is the deliverable
PF_BaseCaseRevenue $33,000,000
less generation basis change ($2,607,000)
less curtailment ($1,215,720)
less basis and capture ($2,334,182)
less availability ($542,231)
PF_BankingCaseRevenue $26,300,867
PF_BaseCaseDebtCapacity $240,749,224
PF_BankingCaseDebtCapacity $186,988,855
PF_CaseBridgeDebtEffect $53,760,369
The regime check
PF_BaseCaseBindingConstraint GEARING
PF_BankingCaseBindingConstraint DSCR
Two words that tell both parties what the negotiation is actually about.
The break-even panel
For each key driver, solve for the value at which:
DSCR = lock-up level
DSCR = default level
Equity IRR = hurdle
Binding constraint changes
ℹ️ Note: Report the number of scenarios and their drivers, not just their results. A downside case with no stated driver is a haircut with a label, and it cannot be argued about productively because nobody can say what would have to happen for it to occur.
To build the case switch, the bridge and the break-even panel, prompt Dezzmond with your base case and the lender's assumptions.
What Do Sponsors and Lenders Actually Check?
- Does a written bridge exist between the sponsor investment case and financing Base Case Model?
- Is the binding constraint the same in both? If not, the parties are negotiating different things.
- Is the base case genuinely unconservative, or has prudence leaked into it?
- Are downside cases coherent scenarios or stacked independent haircuts?
- Have correlated drivers been modelled as correlated?
- Does the model publish break-evens as well as cases?
- Is it one workbook with a case switch, or several files that have diverged?
Frequently Asked Questions
What is the difference between a sponsor case and a financing Base Case Model?
The sponsor case is an internal investment / valuation case. A financing Base Case Model is whatever the credit agreement defines and may be borrower-prepared, lender-approved and IE-certified. It can use P50 or other specified assumptions. Do not rely on the label alone.
How large can the gap be?
Transaction-specific. In the worked example, four assumption changes reduce revenue by 20.3%, CFADS by 22.3% and coverage-based debt capacity by $53.8m. Those figures are scenario outputs, not a market range.
Why does the binding constraint change between cases?
Because the worked Sponsor Case sits above the gearing / coverage crossover while the worked Lender Sizing Case sits below it. The same financing can therefore be gearing-constrained in one case and DSCR-constrained in another.
What is the difference between a sensitivity and a scenario?
A sensitivity moves one variable to show its marginal effect. A scenario moves a coherent set of assumptions representing a possible state of the world. Both are useful and answer different questions.
What does a model audit actually check?
Whatever the engagement scope requires. Formula / logic testing and consistency with finance documents are common; technical, market and other assumptions can be validated by separate advisers.
What happens if the financing case moves before financial close?
Debt sizing can move and the sponsor equity requirement can change. The relevant protections and flex depend on the term sheet and finance documents, so model the sensitivity before signing.
What is the single most useful downside output?
Often a break-even or headroom measure: the point at which a covenant, hurdle or sizing constraint binds. It complements scenarios because it shows how far the structure can move before the outcome changes.
Closing: One Instruction Across the Series
This closes Returns & Valuation, and the pattern across the blog is consistent:
state exactly what a number measures, then publish the thing it cannot tell you.
A P90 needs its period and uncertainty scope. A DSCR needs its CFADS definition. An IRR needs its cash-flow perimeter. A contingency percentile needs its risk-model scope. A debt amount needs its binding constraint. A financing Base Case Model needs an explicit bridge back to the sponsor investment case.
Most expensive model surprises are not caused by arithmetic. They come from a number being correct under one definition and read under another.
The durable modelling habit is therefore to pair every headline metric with its boundary conditions:
Ratio → definition + headroom
Return → cash-flow perimeter + capital required
Percentile → period + uncertainty scope
Debt amount → sizing case + binding constraint
Case → owner + source + bridge to other cases
That makes the model auditable, comparable and negotiable — which is what matters once the spreadsheet becomes a financing document.
Related reading: P50, P90 and P99 energy yield · DSCR vs gearing debt sizing · Project-finance cost of capital
Sources: SEC-filed credit agreement — Base Case Model defined using P50 Production, Eligible Revenues and Operating Expenses · 2026 DOE-supported financing — certified Base Case Financial Model, CFO variance explanation and Financial Advisor / Independent Engineer confirmation · 2026 SEC-filed credit agreement — updated Base Case Model subject to Required Lender review and IE certification · Dezzmond analysis; Sponsor / Lender Sizing Case bridge is illustrative.