Renewable Curtailment Calculator
Curtailment — renewable generation that operators instruct to shut down because the grid cannot accept it — is a growing cost to grid decarbonization, and at the system level it is a different question from a single project's revenue loss. This calculator takes a region's total renewable generation available (MWh/year), a curtailment rate (%), and the value of curtailed energy ($/MWh), then reports the curtailed energy, the delivered renewable energy, and the annual economic value of the energy lost. It is the grid-planning counterpart to our Curtailment Loss Calculator, which focuses on one project's revenue impact, and it pairs with our Reserve Margin / Capacity Adequacy Calculator for the broader resource-adequacy picture.
The total renewable energy (wind + solar combined) a region's resources could generate absent any curtailment.
EIA data shows ERCOT curtailed about 5% of available wind generation in 2022, projected to potentially rise toward 13% by 2035 without major transmission upgrades. Rates vary significantly by region.
Representative wholesale or PPA-equivalent value; adjust to your specific market.
total renewable generation available (MWh/year) × (curtailment rate (%) ÷ 100)
total renewable generation available (MWh/year) − curtailed energy (MWh/year)
curtailed energy (MWh/year) × value of curtailed energy ($/MWh)
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →At the system level, curtailment represents a real, growing cost to grid decarbonization efforts -- not just an inconvenience for individual project owners. A regional grid with 5,000,000 MWh of annual renewable potential curtailing just 5% loses 250,000 MWh of clean energy and roughly $7.5 million in economic value every year, energy that could have displaced fossil generation elsewhere on the system. As EIA data shows regions like ERCOT could see curtailment rates climb toward 13% by 2035 without major transmission upgrades, understanding system-wide curtailment costs -- not just individual project losses -- is becoming an increasingly important grid-planning metric.
How renewable curtailment is calculated
This calculator takes a system-level, technology-agnostic view of curtailment — the total volume and economic value of clean energy a region loses across all its wind and solar generation, relevant to grid operators and policy analysis rather than a single asset's owner. Three quantities tie the calculation together.
Curtailed Energy (MWh/year) = Total Renewable Generation Available (MWh/year) × (Curtailment Rate (%) ÷ 100). The curtailment rate is the share of available renewable generation that grid operators instruct to shut down because the system cannot accept it. At the defaults — 5,000,000 MWh available and 5% curtailment — that is 5,000,000 × 0.05 = 250,000 MWh/year.
Delivered Renewable Energy (MWh/year) = Total Renewable Generation Available (MWh/year) − Curtailed Energy (MWh/year). This is the clean energy that actually reaches customers. At the defaults, that is 5,000,000 − 250,000 = 4,750,000 MWh/year.
Annual Value of Curtailed Energy ($) = Curtailed Energy (MWh/year) × Value of Curtailed Energy ($/MWh). The value per MWh is a representative wholesale or PPA-equivalent price for the curtailed energy; at 250,000 MWh and $30/MWh, that is 250,000 × $30 = $7,500,000/year.
Two notes on the model. First, this is a system-wide aggregate — it does not distinguish wind from solar, or one project from another, and it does not allocate curtailment by cause (transmission congestion, oversupply, or reliability constraints). Second, curtailment rates vary significantly by region, grid operator, and year: EIA data shows ERCOT curtailed about 5% of available wind generation in 2022, projected to potentially rise toward 13% by 2035 without major transmission upgrades, so the default rate is illustrative rather than universal. Data sources: System-wide renewable curtailment rates and trends from U.S. Energy Information Administration (EIA) and NERC (North American Electric Reliability Corporation) grid operations data; ERCOT wind curtailment data from EIA and ERCOT operator reports; transmission congestion and curtailment causes from grid operator technical reports and FERC filings; renewable curtailment impact on decarbonization from NREL grid integration and renewable energy studies; battery storage and demand response solutions for curtailment reduction from NREL and EPRI research; economic value of curtailed renewable energy from wholesale electricity market analysis and PPA pricing data. Verification: with defaults (5,000,000 MWh available, 5% curtailment, $30/MWh), Curtailed Energy = 250,000 MWh/year, Delivered Renewable Energy = 4,750,000 MWh/year, Annual Value of Curtailed Energy = $7,500,000.