Methodology & sources
Every Ohmic default is traceable to a public source. Each tool also has its own “Sources & methodology” panel listing the exact defaults it uses. Anything that is a modelling choice rather than a sourced fact is marked assumption.
Wholesale pricesTime conventionsStatisticsGasRetail tariffsData confidentialityTool methodsKnown gaps
Wholesale electricity prices
Seed curves are hourly locational marginal prices (LMPs) for trading hubs and load zones, downloaded from each ISO's public market data using the open-source gridstatus library (BSD-3). Administrators can add or replace curves (for example nodal prices) by upload. Every upload is validated, versioned and attributed.
| ISO | Seed locations | Markets | Official source |
|---|---|---|---|
| CAISO | NP15, SP15, ZP26 trading hubs | DA hourly; RT 15-min averaged to hourly; DA AS | CAISO OASIS |
| ERCOT | Hubs (HB_*) and load zones (LZ_*) | DA hourly SPP; RT 15-min SPP averaged to hourly; DA AS (MCPC) | ERCOT MIS (NP4-180-ER historical DAM hub and load-zone prices; NP6-785-ER historical RTM prices; NP4-181-ER historical DAM clearing prices for capacity) |
| NYISO | All 15 LBMP zones | DA and RT hourly; DA AS | NYISO OASIS |
| ISO-NE | Internal Hub and 8 load zones | DA hourly; RT hourly | ISO Express |
| MISO | 8 commercial hubs | DA ex-post hourly; RT hourly final | MISO market reports |
| SPP | North and South hubs | DA hourly; DA operating reserves | SPP Marketplace portal |
| PJM | Added by upload or once API access is provisioned | — | PJM Data Miner 2 |
Time conventions
- All hourly series are stored on an hour-beginning, local-standard-time axis with no daylight-saving shifts: 8,760 hours (8,784 in leap years), hour 0 = 1 January 00:00–01:00 standard time.
- Standard offsets from UTC: CAISO −8; ERCOT and SPP −6; MISO, PJM, NYISO and ISO-NE −5. MISO publishes in Eastern Standard Time year-round, so no conversion is needed. ISOs that publish in prevailing time are converted, and the repeated November hour is resolved by order of appearance assumption.
- Sub-hourly real-time prices are simple-averaged to the hour. This differs slightly from settlement-weighted averages assumption.
- Charts show hour of day in the ISO's local standard time.
Price statistics
- On-peak is 5×16: hour-beginning 06:00–21:00, Monday–Friday, local standard time. NERC holidays are not excluded assumption. Off-peak is all other hours.
- TB2 / TB4 spread is the mean, across days, of the top-2 (top-4) hourly prices minus the bottom-2 (bottom-4) hourly prices in each day. It is a common screening metric for 2-hour and 4-hour storage arbitrage and is not a dispatch result.
- Percentiles use linear interpolation. Missing hours are excluded and counted.
- Price-duration curves show 101 points (0th–100th percentile, descending).
Natural gas
Henry Hub daily spot prices come from EIA series RNGWHHD. State electric-power-sector delivered prices are monthly, from EIA Natural Gas Prices, Electric Power Consumers. They are converted from $/Mcf to $/MMBtu using the annual heat content of natural gas consumed by the electric power sector from EIA Monthly Energy Review Table A4 (1.033 MMBtu/Mcf in 2023; 1.034 in 2024 and 2025). Where a tool needs hourly gas, the daily or monthly price is held constant over each day or month. Weekend and holiday daily prices carry forward the last trading day assumption.
Retail tariffs (Ohm-Rate)
Ohm-Rate uses the U.S. Utility Rate Database (OpenEI, CC0) and EIA Form 861 utility data. Tariffs are shown with their URDB effective date, so you can judge how current they are. Coincident-peak and reactive-power charges are not billed, and export/net-metering credits are not modelled yet.
Data confidentiality
Access is granted per tool and per price series by your administrator. Prices are displayed as charts and summary statistics only. Raw price series cannot be downloaded or retrieved through the API. All aggregation, dispatch and revenue calculations run on Ohmic's servers, and only their processed outputs (results, KPIs, reports) can be exported. Views carry a watermark identifying the user.
Tool methods
Each tool page documents its engine: inputs, equations, defaults with sources, and validation cases. Engines are deterministic JavaScript that runs server-side. Shared conventions:
- Money is nominal US dollars unless a tool states otherwise. Energy prices are in $/MWh; capacity is in $/kW-month or $/MW-day, as labelled.
- Battery and hybrid dispatch uses perfect-foresight optimisation against historical prices. This is an upper bound on achievable merchant revenue. Tools that apply a forecast-error haircut say so explicitly assumption.
- Financial metrics (NPV, IRR, LCOE/LCOS) use the shared Ohmic finance module: MACRS depreciation, ITC/PTC with bonus adders as specified in the Inflation Reduction Act, and debt sized either as a fixed fraction of capex or as the largest level-payment loan that keeps every year's debt service coverage at or above a target ratio. Assumptions are listed in each run's output.
Known data gaps
- CAISO 2023: CAISO OASIS no longer serves 2023 via its API (rolling retention). 2024–2025 are loaded.
- PJM: pending API provisioning. Administrators can upload PJM Data Miner exports.
- SPP: day-ahead seed data covers 2025. Real-time and earlier years can be uploaded.
- ISO-NE and MISO ancillary-service prices are not in the seed set.