Field-by-field reference
for every platform.
Plain-English explanations, concrete examples, and practical tips for every input across VIPER, the Firming Cost Analyzer, and the Accounting Engine.
VIPER — Nodal Scenario Analysis
What It Does
VIPER is a browser-based power system model of ERCOT at 187-county resolution. It uses pre-computed PTDF (Power Transfer Distribution Factor) sensitivities so you can add or remove generation, storage, or load at any bus and see how locational marginal prices (LMPs), transmission flows, and constraint shadow prices change — in under 100 milliseconds.
Think of it as a “what-if” tool for the grid. Instead of running a full production cost model (which can take hours), VIPER gives you directionally accurate results instantly so you can iterate on dozens of scenarios in a single session.
Running a Scenario
Select any of the 187 county-level buses on the ERCOT map. Each bus represents a real electrical node where generation or load connects to the transmission network.
Specify the MW amount and resource type (solar, wind, gas, storage, or load). Positive values add generation; negative values retire it.
VIPER recalculates LMPs at every bus, updates transmission flows, and flags any constraints that bind or relax as a result of your change.
Reading LMP Results
The change in the locational marginal price at a given bus caused by your scenario. A negative delta means your addition suppressed the local price.
How much the system cost would decrease if a binding transmission constraint were relaxed by 1 MW. High shadow prices indicate bottlenecks worth investigating.
The shift in power flow on a transmission element caused by your scenario. Large flow changes near thermal limits may signal reliability concerns.
The number of hours per year a constraint is at its thermal limit. More binding hours mean more frequent congestion and higher congestion costs.
Firming Cost Analyzer
What It Does
The Firming Cost Analyzer takes your data center load profile and site-specific renewable generation data, then dispatches battery storage (BESS) and gas backup optimally across all 8,760 hours of a year. The result is the true all-in cost, carbon intensity, and hourly clean-energy matching percentage of any portfolio configuration — before you sign a PPA.
It answers the question: “If I pair X MW of solar, Y MW of wind, and Z MWh of storage with my load, how often do I still need gas, and what does it all cost?”
Configuring a Portfolio
Your hourly electricity demand in MW for a full year. Upload as a CSV with one column of 8,760 values. This is the demand the portfolio must cover.
Net capacity factors for each renewable resource — the fraction of nameplate output each hour. Site-specific NCFs are far more accurate than generic P50 estimates.
The installed capacity of each resource (solar, wind, BESS). Scale these up or down to find the portfolio size that hits your cost and clean-energy targets.
How many hours the battery can discharge at full power. A 100 MW / 4-hr BESS stores 400 MWh. Longer duration covers more overnight gaps but costs more.
The variable cost of gas-fired backup. Used to calculate the blended $/MWh when renewables + BESS are exhausted.
The emission intensity of gas backup. Combined with gas dispatch hours, this determines portfolio carbon intensity.
Reading Dispatch Outputs
The percentage of hours where clean energy (renewables + BESS) fully covers load with zero gas. 90% means gas only fired in 876 hours.
The all-in cost per MWh across all sources — renewable PPA price, BESS cycling cost, and gas variable cost, weighted by dispatch.
Total portfolio emissions divided by total MWh served. Driven almost entirely by how many hours gas fires.
Excess renewable generation that cannot be stored or consumed. High curtailment means the portfolio is oversized relative to load + storage.
Lease & Derivative Accounting Engine
Contract Types
The engine handles three types of energy contracts, each with its own accounting standard and calculation path.
The lessee effectively owns the asset. Recognized as a right-of-use (ROU) asset and lease liability on the balance sheet. Expense is split into interest (front-loaded) and ROU depreciation.
The lessee uses the asset but does not own it. Still on the balance sheet (ASC 842 change), but total lease expense is recognized on a straight-line basis over the term.
A financial contract whose value derives from commodity prices (e.g., a fixed-price PPA vs. floating market). Marked to market each period with gains/losses in the P&L.
Derivative Field Reference
Notional Volume
The total quantity of energy (in MWh or MMBtu) covered by the derivative contract. This is the 'size' of the position.
A 50 MW solar PPA running 8,760 hours at a 25% capacity factor → Notional Volume = 50 × 8,760 × 0.25 = 109,500 MWh.
Use expected delivery, not nameplate. If the PPA has a guaranteed minimum, use that. The engine multiplies this by the price difference to determine fair value.
Unit
The unit of measure for the notional volume — typically MWh for power or MMBtu for gas. Must match the unit used in forward curves.
A power PPA uses MWh. A gas supply agreement uses MMBtu.
If your forward curve is in $/MWh, set Unit to MWh. Mismatched units will produce incorrect mark-to-market values.
Contract Price
The fixed price per unit locked in by the derivative. The engine compares this to the forward curve to determine whether the contract is in- or out-of-the-money.
A PPA with a $35/MWh fixed price vs. a forward curve averaging $42/MWh → the contract is $7/MWh in-the-money.
Enter the all-in fixed price including any adders (e.g., REC premiums). Exclude variable pass-throughs like congestion charges.
Discount Rate
The annual rate used to discount future cash flows to present value. Drives the net present value (NPV) of the mark-to-market position.
At a 5% discount rate, a $100,000 cash flow 3 years out is worth $100,000 ÷ 1.05³ = $86,384 today.
Use your company's incremental borrowing rate or WACC. A higher rate reduces the reported fair value of long-dated contracts.
Day 1 Zero-Out
When enabled, the engine calculates a coefficient that zeroes out the Day 1 fair value, then amortizes it over the contract term. Required when a derivative has non-zero fair value at inception without an upfront payment.
A PPA signed at $35/MWh when forwards are $42/MWh has a positive Day 1 value. The zero-out coefficient offsets this so the opening P&L entry is $0.
Enable this for any at-market PPA where no cash changes hands at signing. The amortization method (below) determines how the offset unwinds.
Amortization Method
How the Day 1 zero-out coefficient unwinds over the contract life. 'Volumetric' ties amortization to expected delivery each period. 'Straight-Line' spreads it evenly across months.
A 3-year PPA with seasonal delivery: Volumetric assigns more amortization to summer months (higher generation). Straight-Line assigns 1/36 per month regardless.
Volumetric better matches the economics of weather-dependent resources (solar, wind). Straight-Line is simpler and defensible for baseload contracts.
Forward Curve
The market price forecast used to mark the derivative to market each period. Can be uploaded as a CSV, pulled from a benchmark, or entered manually.
A CSV with columns [Date, Price]: 2025-01, $41.50 | 2025-02, $39.80 | 2025-03, $38.20 … one row per delivery month.
CSV format: two columns, Date (YYYY-MM) and Price ($/unit). If no curve is uploaded, the engine falls back to a flat benchmark price. Update curves monthly for accurate MTM.
Lease Field Reference
Finance vs Operating Classification
Determines how lease expense hits the P&L. Finance leases split expense into interest + depreciation (front-loaded). Operating leases recognize a single straight-line expense.
A 10-year solar lease where the lessee owns the panels at term end → Finance. A 5-year office lease with no purchase option → Operating.
ASC 842 uses five criteria: transfer of ownership, purchase option, lease term vs. useful life (≥75%), PV of payments vs. fair value (≥90%), and specialized asset. If any one is met, classify as Finance.
Asset Type
The type of energy asset being leased. Each asset type has a default useful life that drives ROU depreciation.
Natural Gas → 30 years. BESS → 15 years. Solar → 25 years. Wind → 20 years.
These defaults can be overridden with the Useful Life field. Choose the asset type that most closely matches the underlying equipment.
Useful Life
The total economic life of the underlying asset in years. Used to depreciate the ROU asset for finance leases and to evaluate the 75% classification threshold.
A BESS with a 15-year useful life under a 12-year lease → 12/15 = 80% ≥ 75% → meets the finance lease threshold.
If left blank, the engine uses the default for the selected Asset Type. Override only when the specific asset has a materially different expected life.
Fixed Payment
The periodic lease payment amount in dollars. This is the base payment before escalations. Used to compute lease liability (PV of all payments) and ROU asset.
$150,000 per month for a solar ground lease. Over 120 months at 5% IBR, the present value (lease liability) is approximately $14.2M.
Enter the payment amount that matches your Payment Frequency. If your lease has both fixed and variable components, enter only the fixed portion here.
Payment Frequency
How often lease payments are made — Monthly, Quarterly, or Annually. Affects the number of periods in the amortization schedule and the per-period discount rate.
A $150,000/month lease has 120 periods over 10 years. The same lease paid quarterly ($450,000/quarter) has 40 periods.
Monthly is most common for energy asset leases. The engine automatically converts the annual IBR to the matching periodic rate.
IBR Rate (Incremental Borrowing Rate)
The annual interest rate used to discount lease payments to present value. Should reflect what the lessee would pay to borrow a similar amount on a collateralized basis over a similar term.
A lessee with BBB credit and a 10-year lease term might use 5.5% — roughly the yield on a 10-year BBB corporate bond.
If the rate implicit in the lease is not readily determinable (it usually isn't), use your IBR. Check with your treasury team — this rate significantly impacts the lease liability.
Net ABV (Adjusted Book Value)
The net adjusted book value of the underlying asset. Used for impairment monitoring — if the ROU asset exceeds the Net ABV, the engine flags a potential impairment.
A solar array with a $20M original cost, $4M accumulated depreciation, and $1M impairment → Net ABV = $15M. If ROU is $16M, impairment flag triggers.
Update this value when the underlying asset is reappraised or when accumulated depreciation changes materially. The engine compares ROU vs. Net ABV each period.
Escalation Schedule
Annual percentage increases to the base lease payment. When an escalation occurs, the engine remeasures the lease liability using the remaining payments at the original discount rate.
A $100,000/month lease with 3% annual escalation → Year 2 payment = $103,000/month, Year 3 = $106,090/month. The liability is remeasured at each step-up.
Enter escalation as an annual percentage (e.g., 3 for 3%). Known escalations are included in the initial measurement. Only contingent escalations trigger remeasurement.
Early Termination Option
A contractual right to end the lease before the stated term. If 'reasonably certain' to be exercised, the engine shortens the lease term to the termination date.
A 15-year lease with a Year 10 termination option. If reasonably certain to terminate → lease term = 10 years, reducing both liability and ROU asset.
Check the 'Reasonably Certain' box only if there is significant economic incentive to terminate (e.g., penalties are low relative to remaining payments). This decision is revisited each reporting period.
Results & Export
After the engine calculates, results are organized into dashboard tabs. Each tab can be exported individually or as a combined package.
Month-by-month breakdown of lease liability, interest expense, principal reduction, and ROU asset balance. For operating leases, includes the straight-line expense and plug ROU amortization.
Balanced debit/credit entries for each accounting period — ready to post. Covers initial recognition, monthly amortization, escalation remeasurement, and impairment (if flagged).
Period-over-period mark-to-market gains and losses. Shows the contract fair value, Day 1 zero-out amortization (if enabled), and net P&L impact for each period.
Compares the ROU asset carrying amount to the Net ABV each period. Flags when ROU exceeds Net ABV and provides the impairment journal entry on demand.
Standard comma-separated file with headers. Works with any ERP or spreadsheet tool. Includes all columns from the selected dashboard tab.
Pre-formatted for SAP FI posting. Maps journal entry fields to SAP document type, posting key, G/L account, and cost center fields.
Pre-formatted for NetSuite CSV import. Maps to NetSuite journal entry columns including subsidiary, department, and memo fields.
Still have questions about a specific field or workflow?