# Energy curtailment Source: https://ordergroup.co/glossary/energy-curtailment/ Last updated: 2026-10-10 > Energy curtailment for teams building EMS and solar software: grid operator orders, export limits, zero export and what the control system must handle. [Energy](https://ordergroup.co/glossary/energy/) 4 min read # Energy curtailment Also known as: curtailment, export limitation, export limit, zero export, antireflux, anti-reflux Definition Energy curtailment is a deliberate reduction of a generator's output, usually solar or wind, below what it could produce. A grid operator orders it to keep the system balanced or a line within limits, or it is set locally as an export limit at the grid connection. Cite this entry Text "Energy curtailment". Order Group, Software glossary, 10 October 2026. https://ordergroup.co/glossary/energy-curtailment/ HTML `Energy curtailment - Order Group` Reviewed by [Paweł Zieliński](https://ordergroup.co/authors/pawel-zielinski/), Co-founder & Business Owner Last reviewed 10 October 2026 ## How energy curtailment works EU law treats curtailment as one kind of redispatching. Regulation (EU) 2019/943, Article 2(26), defines redispatching as a measure, including curtailment, activated by transmission or distribution system operators that alters generation, load or both in order to change physical flows, relieve congestion or otherwise ensure system security. Article 13 sets the order of preference. Redispatching should be market-based and paid. Non-market-based redispatching is allowed only in listed cases, for example when no market-based alternative exists or all market resources have been used. Renewable generators may be curtailed this way only if no other alternative exists, and self-generated electricity that is not fed into the grid should not be curtailed unless no other solution resolves a network security issue. Article 13(7) requires the operator that orders non-market-based redispatching to pay financial compensation, unless the plant accepted a non-firm connection agreement, one with no guarantee of firm delivery of energy. In practice an engineer meets curtailment in four forms, and only the first is what the regulation calls redispatching. A system operator orders a plant to reduce output or switch off. A connection agreement caps how much power the site may export. A zero-export rule forbids export altogether, so PV output is limited to what the site consumes and the battery absorbs. And an owner or trader curtails voluntarily when the price of exported energy drops to zero or below. Forms of curtailment and who triggers them TypeTriggered bySignalCompensation Non-market-based redispatchingTransmission or distribution system operatorOrder to reduce output or switch offYes, under Article 13(7), unless the plant accepted a non-firm connection agreementConnection export limitConnection agreementFixed cap at the connection pointNo, it is a condition of the connectionZero exportGrid rule or owner's choiceNo export at the connection pointNoPrice-based curtailmentOwner or traderZero or negative export priceNo ## Curtailment in Poland Article 13(4) of the regulation obliges operators to report redispatching every year, and URE publishes the summary. For 2024 URE reported that, on PSE's orders, non-market redispatching of PV plants reduced generation by 595,168.4 MWh to balance the national power system and by 2,095.7 MWh because of transmission constraints. For wind the figures were 118,047.6 MWh and 7,027.7 MWh. Distribution operators curtailed a further 24,121.1 MWh of PV on their own orders, and only 3 of the 188 distribution operators did so. URE describes non-market redispatching of renewables for balancing as a last-resort action. PSE first limits generating units on the balancing market, uses pumped storage, redispatches thermal units outside the balancing market and redispatches across borders. Only then does it order renewable plants to reduce output, directly for plants connected to the transmission grid and through distribution operators for the rest. The same orders can also switch off an energy storage unit or change the power it takes or delivers. ## What curtailment means for your software For an [EMS](https://ordergroup.co/glossary/ems/) curtailment is a constraint that arrives from several directions at once and has to win over everything except safety. Requirements worth specifying: - Signals have a written priority. Safety limits, grid operator orders, connection export caps, [peak shaving](https://ordergroup.co/glossary/peak-shaving/) and trading will all act on the same inverters and battery. The system needs a fixed order and a screen that shows which rule is limiting output right now. - Each controller reacts to its own trigger. A safety controller that throttles the battery whenever any limit is active will cost energy for no reason. - The limit is enforced at the connection point. The EMS reads the grid meter, compares export with the limit and adjusts the inverters in a closed loop. The loop needs a margin for inverter response time, and a safe fallback, such as zero export, when the meter stops responding. - Surplus goes into the battery before PV is cut. With a battery on site, the EMS can charge it with energy that may not be exported, which needs headroom in the battery's [state of charge](https://ordergroup.co/glossary/state-of-charge/) before the expected curtailment hours. - Forecasts and reports know about curtailment. A production forecast for hours with export blocked should be capped at consumption plus battery charging, or the app will show energy that was never produced. - Every event leaves evidence. Compensation and disputes depend on the start, end and value of the limit, the power the plant could have produced and the power it actually produced. Writing the specification? Add Energy curtailment to your requirements checklist Collect the terms your project touches and get their system requirements in one e-mail, ready for an RFP. Data the EMS stores during a curtailment event RecordWhy it is needed Signal source and identifierShows which rule limited outputStart, end and limit valueMatches the order or the connection conditionAvailable power and actual outputBasis for lost energy and compensationBattery state of charge and charging powerShows whether surplus could have been storedSetpoints sent and values read backProves that the site complied ## From our projects The EMS we built for [Skyfri](https://ordergroup.co/case-studies/skyfri-solar-asset-management-platform/) takes signals from the distribution system operator that limit the export of a factory's energy to the grid for grid safety. By October 2024 it included export curtailment on grid operator request, zero-export and zero PV export algorithms, and a maximum site load limiter, tested on site with the grid operator. For Global Green's battery storage sites we built separate controllers in 2026: - the distribution operator's export limit, - the distribution operator's battery limit and direct battery commands, - PV export limitation and grid export limitation, - a safety curtailment controller. Testing showed that the safety controller throttled the battery regardless of what had triggered it. We fixed it in September 2026. In [Zeronest's](https://ordergroup.co/case-studies/zeronest-solar-panel-monitoring-app/) home EMS, anti-reflux (blocking export to the grid) is one of the manual battery modes, and the automatic algorithm switches to it when the price for exported energy is zero or negative. In 2026 we corrected the production forecast so that, in hours with anti-reflux planned, it shows no more than consumption plus battery charging. From our projects [Skyfri - Solar & Battery Asset Management Platform How Order Group built the fully offline EMS behind Skyfri's solar platform, which controlled more than 5 MWh of battery storage across 7 live plants.](https://ordergroup.co/case-studies/skyfri-solar-asset-management-platform/) ## Related terms - [Demand response](https://ordergroup.co/glossary/demand-response/) Demand response is a change in electricity consumption by end users, away from their normal pattern, in reaction to prices or to a paid call from a grid operator or aggregator. It can be offered by one site or by many sites pooled through aggregation. - [EMS](https://ordergroup.co/glossary/ems/) Energy management system An energy management system (EMS) is software that reads the meters, inverters and batteries on a site and sends them setpoints, deciding when to charge, discharge, curtail or trade within grid, contract and safety limits. - [Peak shaving](https://ordergroup.co/glossary/peak-shaving/) Peak shaving lowers the highest power a site draws from the grid, usually by discharging a battery or cutting flexible load during the intervals the network tariff measures, so the site avoids capacity overrun fees or qualifies for a lower network charge. - [State of charge (SoC)](https://ordergroup.co/glossary/state-of-charge/) State of charge (SoC) is the energy available in a battery, expressed as a percentage of its rated capacity. The battery management system estimates it, and energy software uses it to decide when a battery may charge, discharge or hold a reserve. ## Sources 1. [Regulation (EU) 2019/943 on the internal market for electricity, Article 2(26) and Article 13](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019R0943) - EUR-Lex 2. [Sprawozdanie Prezesa URE dotyczące mechanizmów redysponowania w 2024 r. (report on redispatching in 2024)](https://www.ure.gov.pl/download/9/15780/Sprawozdaniedotredysponowaniaza2024r.pdf) - URE Paweł Zieliński reviewed this entry. Ask how it applies to your project. [Ask an engineer](https://ordergroup.co/contact-us/) ## FAQ ![Paweł Zieliński](https://ordergroup.co/media/images/Pawel_p3bY6z4.format-webp.webp) Paweł Zieliński Co-founder & Business Owner [Talk to an engineer](https://ordergroup.co/contact-us/) ### Is curtailment the same as redispatching? Curtailment ordered by a system operator is one kind of redispatching under EU law. Connection export limits, zero export and price-based curtailment are not. Redispatching also covers increases in generation or load, not only reductions. ### Do plant owners get paid when they are curtailed? For non-market-based redispatching, yes: Article 13(7) of Regulation 2019/943 requires financial compensation from the operator that ordered it, unless the plant accepted a non-firm connection agreement. A connection export limit or an owner's own decision at negative prices is not compensated. ### What is zero export? A setting in which the site may not feed any power into the grid at its connection point. PV output is then limited to what the site consumes and what the battery can absorb at that moment. ### Can a battery reduce curtailment losses? Yes, if the EMS charges it with the surplus instead of cutting PV output and leaves enough headroom in its state of charge before the expected curtailment hours. Once the battery is full, PV output has to be reduced. Building a system that depends on Energy curtailment? See how we build software for this domain, with case studies and the stack we use. [See Energy Hub](https://ordergroup.co/energy-hub/) Requirements checklist For each term we send the definition and what it requires from your software. Free, no sales call needed. Your checklist is empty. Use the plus next to a term to add it.