Capacity and energy use different quantities
Energy is measured in kWh or MWh. Capacity commonly concerns power availability in kW or MW over a defined delivery period. Markets use different qualification, auction, and settlement arrangements. PJM’s Reliability Pricing Model is one example, while ERCOT describes an energy-only design rather than an equivalent forward capacity market. Verify the region before explaining a bill. Similar demand-related labels can also refer to utility tariff charges rather than wholesale capacity procurement.
The account obligation matters
An allocation can depend on peak contributions, utility calculations, scaling factors, and other rules. The number shown as a capacity tag may differ from the site’s single highest monthly demand. Ask the supplier which quantity it uses, when it resets, and how it is converted into the billed charge. Market prices and obligation quantities can both change. An agreement can bundle the component, pass it through, or permit specified adjustments; read the relevant schedule and exception clauses.
Peak management requires the right target
Reducing the business’s largest local peak does not necessarily reduce its capacity obligation if the applicable calculation uses system-coincident intervals. Efficiency and flexible operations can help, but the avoided cost depends on measurement rules, timing, and contract treatment. Obtain actual interval and tag data before promising savings. Make sure any load-reduction action preserves critical operations and is compatible with demand-response agreements. A supplier quote cannot guarantee that an operational change will be reflected immediately in the assigned obligation.
Hypothetical unit conversion
Assume a simplified obligation of 0.1 MW and an illustrative capacity price of $200/MW-day for 30 days. The unadjusted calculation is 0.1 × 200 × 30 = $600. Real bills may include obligation scaling, different periods, administration, or bundled treatment. Dividing $600 by 100,000 kWh gives an equivalent $0.006/kWh for that month, but the underlying charge was not a flat energy rate. These numbers are explanatory assumptions, not an auction result or account estimate.
Practical review checklist
- Identify the wholesale region and whether a capacity market component actually applies.
- Obtain the account obligation, measurement period, reset schedule, scaling, and price methodology.
- Read fixed, pass-through, and adjustment language rather than infer coverage from a fixed energy label.
- Model peak-management benefits using the correct intervals and contract treatment before approving a project.
Questions & answers
Is capacity the same as utility demand?
No. Both relate to power, but wholesale capacity allocation and tariffed monthly demand can use different calculations.
Will a new supplier remove capacity costs?
A supplier may bundle or allocate them differently; changing sellers does not erase an applicable underlying market cost.
Sources & scope
Primary references reviewed October 15, 2026. These sources support the stated concepts; actual tariffs, program rules and signed agreements govern the account. Decision examples and operational worksheets are original educational analysis.
- PJM: Capacity Market (RPM)
Capacity auctions, delivery periods, and primary market documents. - FERC: Wholesale electricity markets overview
Wholesale energy, capacity, and ancillary-service functions. - ERCOT: Energy-only wholesale market
Texas energy market design and distinction from a forward capacity market. - DOE FEMP: Evaluating your utility rate options
Demand, ratchets, time-of-use rates, coincident peaks, and standby charges.