How to Assess Curtailment Risk for a Chinese Wind or Solar Project: Utilisation Rates, Who Bears Which Cause, and Where the Data Lives

Short answer. "Curtailment" in China is a defined statistical quantity, not a loose word. The published utilisation rate counts only the energy a plant could not export for system reasons; energy lost to the plant's own faults, to commissioning, to failed grid-code tests or to the plant's own market bids is booked under other headings and does not appear in that rate. A buyer or lender therefore has to read three layers: the national definitions, the provincial targets and weights that drive dispatch decisions, and the plant-level monthly disclosures that the rules oblige grid companies to provide. This guide explains each layer from the primary documents. It quotes no provincial number and makes no forecast.

Layer 1: what the published rate measures

For 2024 the National Energy Administration (NEA) reported a national average wind utilisation rate of 95.9%, on wind generation of 991.6 TWh (up 16%), and a PV utilisation rate of 96.8%, on PV generation of 834.1 TWh (up 44%). The same release notes that 75% of new wind capacity in 2024 went into the "Three North" regions.

The definitions behind those percentages are in the NEA's wind-farm utilisation statistics measures (国能发新能规〔2022〕49号). Curtailed energy (受限电量) is the energy a wind farm could have generated but did not, after excluding the farm's own equipment faults, defects or maintenance. Daily curtailed energy is available-unit generable energy minus actual generation in the curtailed period; system-cause curtailment is total curtailment minus special-cause curtailment, and system causes are defined as load and peak-regulation capability, network constraints and secure and stable operation.

The special-cause list is the one to memorise, because every item on it is excluded from the system's account: force majeure such as typhoons, earthquakes, floods and icing; commissioning or AGC testing and temporary connection schemes; rectification for not meeting grid-connection technical standards; planned maintenance of the export equipment; market-based projects that have not fulfilled their grid-connection conditions; poor market-trading decisions by the wind farm; and major external works, events or special supply-security tasks.

The measures then define two utilisation rates: one counting all curtailment (actual generation ÷ generable energy) and one counting only system-cause curtailment; the published provincial table uses the system-cause-only rate. The 2024 NEA notice on new-energy consumption (国能发电力〔2024〕44号) confirms this as the unified basis — the utilisation rate is calculated considering only system-cause curtailment, grid companies must publish their criteria for recognising special causes, and they must disclose utilisation, available, actual, curtailed and special-cause data monthly to each wind farm and PV station in their dispatch area.

Two consequences follow. First, a national or provincial rate is an average of system-cause curtailment only, so it cannot be read as any single plant's loss; a plant's own figure has to come from its own monthly disclosure. Second, the monthly disclosure to each plant exists by rule, so a seller who cannot produce it has something to explain.

Layer 2: how curtailed energy is measured

Measurement is agreed, not assumed. Curtailed energy is calculated mainly by the nacelle-wind-speed method, with sample-turbine and met-mast-extrapolation methods as verified alternatives agreed between the wind company and the dispatch body; provincial grid companies disclose the monthly data to each wind farm, and the NEA has the national monitoring centre monitor monthly, evaluate quarterly and publish provincial wind consumption on a rolling basis. A due-diligence file should state which method the plant and its dispatch body use, because a method change can move the number without any change in the grid.

The counterpart rule for PV stations (国能发新能规〔2021〕57号) could not be retrieved at a static official URL during this work; the 2024 notice cites both rules together as the statistical basis, and the gap is recorded in the fact map.

Layer 3: targets, weights and the price mechanism

Utilisation targets. The 2024 notice lets provinces with good resource conditions relax their new-energy utilisation target, in principle to not below 90%, with annual dynamic evaluation. Provincial energy authorities bear overall responsibility for the target, propose it in the first quarter and report it to the NEA, which may adjust some provinces' targets; provinces whose actual rate misses the target are urged to rectify through interviews (约谈) and circulars. The notice also requires provinces to analyse regulation needs against new-energy growth and the target, to set annual development plans that specify concentrated projects and commissioning sequence together with a consumption plan, and the NEA to run monthly monitoring, half-year analysis, annual assessment and 3–5-year rolling calculations of each province's utilisation and consumption headroom. The practical reading: the target a province has filed for the current year, and whether it is on the 90% floor, is public policy information a buyer can request.

Export works. Where the grid company cannot build the dedicated export works in time, the generator may invest in them, and the grid company may buy them back later by agreement. A project that built its own line should show the buy-back terms.

Guaranteed purchase. Under NDRC Order No. 15 (2024), a renewable project's exported electricity consists of guaranteed-purchase electricity and market-traded electricity: the former is the quantity market members are obliged to purchase under the consumption-guarantee mechanism and proportion targets; the latter is priced through the market. Electricity not purchased because of the generator's own causes, grid security constraints, grid maintenance, market bids or force majeure is excluded from the guaranteed-purchase scope, and the grid, dispatch and trading bodies must record the specific cause and quantity. Dispatch and trading bodies must disclose the previous month's purchase information to generators by the 8th of each month, and grid companies and generators must record unpurchased electricity and, where necessary, cross-check it with each other. So there are two monthly records — the utilisation disclosure and the purchase disclosure — and they should reconcile.

Market bids. Document 136 (发改价格〔2025〕136号) states that electricity not exported because of a project's market bids is not counted in utilisation statistics and assessment, and that storage may not be made a precondition for approval, grid connection or export of new projects. For projects commissioned from 1 June 2025, each province sets the annual quantity admitted to the price-settlement mechanism with reference to its non-hydro consumption-weight performance: exceeding the weight may reduce next year's mechanism quantity, missing it may increase it. Curtailment risk and price risk are therefore coupled through the weight.

Consumption weights. The 2024 weight notice tells provinces to size guaranteed grid connection of wind and PV according to their non-hydro weight, requires the 2024 renewable share on West-East and inter-provincial corridors to be in principle not below 2023 actuals, and names 冀北, 蒙西, 青海 and 甘肃 as regions that must raise consumption capability and strengthen early warning. The 2025 notice asks provinces to use their 2025 weight performance to optimise the quantity admitted to the price-settlement mechanism and to plan regulation capacity in step with consumption needs. The 2019 founding notice provides that where natural causes (including extreme resource anomalies) or major accidents significantly reduce generation or restrict export, the assessment of provinces and obligated entities is reduced accordingly. At the top of the hierarchy, the Energy Law (adopted 8 November 2024, effective 1 January 2025) requires the state to improve the consumption-guarantee mechanism, with supply, retail, relevant users and self-generation enterprises bearing consumption responsibility, and to build a new-type power system that raises the grid's capacity to accept, allocate and regulate renewables.

Five documents to collect

1. Monthly utilisation disclosures from the grid company to the plant (available, actual, curtailed and special-cause energy), plus the dispatch body's monthly purchase disclosure.
2. The special-cause recognition criteria the grid company has published, and the plant's curtailment calculation method as agreed with dispatch.
3. The provincial utilisation target for the current year and the development/consumption plan it sits in.
4. The provincial weight notices and any mechanism-quantity allocation the project has received.
5. The export-works arrangement — who built the line and on what buy-back terms.

How to read what you collect

Separate the plant's own special-cause items from system-cause items before comparing to the provincial rate; a plant with many commissioning or grid-code rectification months will look worse than the province for reasons unrelated to grid headroom. Check that electricity lost to the plant's own bids is being booked outside the utilisation rate, as Document 136 requires. Then ask whether the province is on the 90% floor or above it, and whether its weight performance points to a larger or smaller mechanism quantity next year. None of these steps needs a forecast model; they need the documents the rules already oblige someone to produce.

Scope limits

No provincial utilisation rate, weight value or curtailment forecast is quoted; the weight tables attached to the 2024 and 2025 notices were not downloaded. The PV-station statistics rule was not retrieved. The 2024 national release is cited from the NEA's "Belt and Road" portal copy. This is a reading guide to public rules, not project advice.