Effective Load-Carrying Capability
ELCC is the share of a power resource's maximum output that a grid operator counts as firm, dependable capacity, based on how reliably the resource actually delivers during the hours the grid is most likely to fall short.
— Overview
One of the most consequential numbers in power
A 100-megawatt solar farm isn't worth 100 megawatts of reliability, because it produces nothing at night and little on a still winter evening when demand peaks. ELCC is how grid operators turn a resource's nameplate rating into an honest measure of what it contributes to keeping the lights on.
It's quietly become one of the most consequential numbers in the power system, since it decides how much a resource earns in the capacity market — and almost no one explains it plainly.
01 — Definition
A percentage of nameplate, earned by showing up
ELCC answers a single question: if you add this resource to the grid, how much additional demand can the system serve at the same level of reliability? Divide that answer by the resource's nameplate rating and you get its ELCC, expressed as a percentage.
A resource that's reliably available when the grid is stressed approaches 100% ELCC. One that tends to be unavailable during peak-risk hours accredits far lower, no matter how large its nameplate.
02 — Methodology
Timing matters more than size
Grid operators run reliability simulations of the entire system across thousands of weather and demand scenarios, with and without the resource, and find how much perfectly-firm capacity the resource is equivalent to at equal reliability.
ELCC isn't a simple nameplate discount or an average capacity factor. It specifically weighs the hours when shortfalls are most likely. So ELCC depends on timing, not just quantity: a resource is judged by whether it shows up at the worst moments.
03 — Origin
A common, honest footing for every resource
Nameplate capacity overstates what variable resources actually contribute to reliability. As grids added wind, solar, and batteries, paying every resource as if its full nameplate were firm would have overpaid intermittent resources and quietly eroded reliability.
ELCC puts every resource — thermal, renewable, storage, and demand response — on the same honest, reliability-weighted footing, so a megawatt of accredited capacity means the same thing whatever produces it.
04 — Comparison
Solar, wind, batteries, flexible load
05 — Economics
A direct multiplier on payment
A resource's capacity payment is its accredited capacity (nameplate multiplied by ELCC) times the capacity price. ELCC is a direct multiplier on revenue.
Raising a resource's ELCC from 69% to 92% is a 33% increase in capacity revenue from the very same physical asset — exactly what PJM did for demand response in its 2027/28 accreditation by rewarding around-the-clock availability.
06 — The Fit
The profile ELCC rewards
A fully interruptible compute load is available around the clock and can curtail deeply for as long as the grid needs — precisely the profile ELCC rewards. Where solar and short-duration batteries lose accreditation as more are added, a deep, long-duration interruptible load holds its value.
In SPP, a ten-hour load accredits near 100% summer ELCC, so a 50 MW interruptible load earns the standing capacity payment of a 50 MW gas peaker without the plant, the fuel, or the emissions. Turning that accreditation into bankable revenue across markets is the work Type 3 exists to do.
Type 3 is the software-defined demand response infrastructure company that turns fully interruptible compute loads into a dispatchable, telemetry-verified grid resource. Read the Manifest →
07 — Coverage
Every market moving the same direction
All three use ELCC-based accreditation to value capacity, and each is tuning its method in ways that favor reliable, around-the-clock resources.
Has no separate capacity payment and accredits reliability differently, through its real-time scarcity pricing.
The direction is consistent across markets: capacity credit is moving toward what a resource actually delivers when the grid is stressed, and away from nameplate.
Ref — FAQ
Ref — Glossary
See the full glossary in the Manifest
Ref — Sources