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Glossary · Energy industry & energy transition

Schedule adherence (Fahrplantreue)

schedule adherence schedule Balancing group Balancing group responsibility Balancing energy electricity market

Schedule adherence describes how closely plan and measurement match in electricity trading. On one side are the registered schedules of a market participant, on the other the actually measured feed-in and withdrawals. It does not mean the technical reliability of an individual plant. It is about how precisely the planned electricity quantities in a balancing group are met, quarter-hour by quarter-hour. In practice, schedule adherence therefore shows how well forecasting, trading, dispatch planning and balancing group management work. In German regulatory texts, the associated obligation is usually called "Bilanzkreistreue" (balancing group compliance) or "ausgeglichene Bilanzkreisbewirtschaftung" (balanced balancing group management). "Fahrplantreue" is more of a practical term.

What a schedule is

The German Electricity Grid Access Ordinance (Stromnetzzugangsverordnung, StromNZV) defines a schedule as follows: it states how much electrical power is exchanged between balancing groups in each time unit, or is fed in or withdrawn at a feed-in or withdrawal point. In Germany, the time unit for balancing is the quarter-hour. A schedule value is usually stated as average power in megawatts. From this follows the energy quantity of the quarter-hour. An example: 10 megawatts over 15 minutes correspond to 10 MW × 0.25 h = 2.5 megawatt-hours.

A schedule does not describe the path by which electricity physically flows through the grid. Load flows result from feed-in, withdrawal and the properties of the grid. The schedule is a commitment for balancing purposes between market roles, balancing groups and time intervals. It reflects the commercial order according to which quantities are registered and settled.

Legal framework in Germany

Under § 4 StromNZV, balancing groups are formed within a control area. Every feed-in or withdrawal point must be assigned to a balancing group. For each balancing group, a balance responsible party (BRP; German: Bilanzkreisverantwortlicher, BKV) is named to the transmission system operator (TSO). The BRP must ensure that feed-in and withdrawals are balanced in every quarter-hour. This balancing responsibility is the actual foundation of schedule adherence.

The standard balancing group contract of the Bundesnetzagentur (Federal Network Agency) regulates the details. Under it, the BRP is responsible for three things: a balanced quarter-hourly power balance, proper schedule management, and the financial settlement of the remaining deviations. The BRP's registered schedules must be complete and balanced for every quarter-hour. Schedules with other balancing groups must be agreed with them beforehand. The contract rules cited here come from the version that has applied since 1 August 2020. Later changes are possible; the current version is always the one that governs.

Balancing group deviation and balancing energy

One clarification is important: a deviation is not determined for each individual schedule, but for the balancing group as a whole. According to the balancing group contract, the balancing deviation is the difference per quarter-hour between two sums. The first sum covers all inflowing quantities: measured feed-in and incoming schedules. The second covers all outflowing quantities: measured withdrawals and outgoing schedules. The TSO determines this difference from the meter readings of grid operators and metering point operators. It then multiplies it by the cross-control-area uniform balancing energy price (reBAP) and settles it with the BRP as balancing energy.

This yields the economic core of schedule adherence. Anyone who plans poorly draws or supplies balancing energy at the reBAP. This price can fluctuate strongly and can be very high in tight quarter-hours. Good planning reduces this cost risk.

A widespread notion needs correcting here. Balancing energy is neither a freely selectable procurement instrument nor a merely neutral settlement item. According to the balancing group contract, it may only be used to offset deviations that cannot be forecast. Positions deliberately left open, for example to profit from price differences, violate the obligation of balanced management. In a position paper, the Bundesnetzagentur clarified that balancing groups must be managed with quarter-hour precision. It asked the TSOs to review settlements specifically for breaches of duty and to submit cases. The trigger was considerable system imbalances during steep load and generation ramps, for example on 24 December 2012.

There is an exception for unplanned outages. If a power plant fails, the BRP is exempt from the balancing obligation for four quarter-hours, including the quarter-hour of the outage. This applies only to the deviations caused by the outage. After that, the BRP must replace the missing power itself, for example through trading or its own reserves.

Distinction from grid stability and forecast quality

Schedule adherence is not the same as grid stability. In real time, the TSOs offset the imbalance of all balancing groups together using control energy and thereby stabilise the frequency. Only the subsequent balancing group settlement allocates the costs to those who caused them. A balancing group can be well managed while bottlenecks nevertheless occur in the grid. Conversely, the system can run stably even though individual balancing groups deviate. However, many deviations in the same direction can place heavy demands on reserves. In the case of 24 December 2012, according to the Bundesnetzagentur, all reserve products were at times exhausted.

Nor is a good forecast automatically schedule adherence. Forecasts estimate future generation or demand. Schedule adherence shows whether the balance actually adds up in the end. In between lie several steps: trading, dispatch planning, availability of plants, actual weather developments and short-term corrections.

Short-term corrections and quarter-hour trading

Schedule adherence does not mean rigidly sticking to a day-ahead plan. It means the ability to bring plan and reality into line until shortly before delivery. Under the 2020 version of the balancing group contract, schedules between German control areas can be changed for every quarter-hour of a day with a lead time of at least one quarter-hour. If it becomes apparent in the morning that more or less wind power will arrive in the afternoon than expected, the BRP can adjust its position via the intraday market. Intraday schedule registrations may be temporarily unbalanced. However, at the latest one quarter-hour before the start of delivery, the balance must be restored.

Quarter-hour planning has also become easier in wholesale trading. Since the delivery day of 1 October 2025, quarter-hour products rather than hourly products have been traded in the European coupled day-ahead market. Previously, balancing groups had to restructure their hourly trades into quarter-hours in intraday trading. Today, the quarter-hour structure can be reflected directly on the day before.

Renewables, storage and flexibility

With more wind and solar power, schedule adherence becomes more demanding, but not impossible. Weather-dependent generation cannot be planned as precisely as a controllable power plant. Several things, however, clearly reduce deviations: updated forecasts, real-time data, smoothing effects across large areas and short-term trading. For power plants, availability, start-up times and minimum output matter most. For consumers, production plans, temperature and consumption behaviour matter.

Storage, controllable generators and flexible consumers can cushion forecast errors in their own balancing group. An example: a battery feeds in when a solar plant delivers less than planned. It charges when more electricity is generated than expected. Industrial load shifting, heat pumps with buffer storage or controlled charging of electric vehicles can also help. The prerequisite is that these assets are measurable and controllable and are contractually integrated into balancing group management. Schedule adherence is thus closely linked to the topic of flexibility. Suppliers, direct marketers or an aggregator often pool many small plants in one balancing group and control them together.

Typical misunderstandings

  • Schedule adherence does not require a perfect forecast. What is required is that deviations are responsibly managed in an orderly way: foreseeable deviations are to be avoided, while unforeseeable ones are settled via balancing energy.

  • Balancing energy is not an arbitrary trading venue. Anyone who deliberately remains unbalanced breaches the balancing group obligations, even if they pay the reBAP for it.

  • High schedule adherence says nothing about whether an electricity system is cost-efficient, climate-compatible or secure in supply. A balancing group can plan very precisely and still procure expensive or emission-intensive electricity.

  • High schedule adherence does not prevent grid bottlenecks. Bottlenecks are handled with separate instruments such as redispatch, not through balancing group settlement.

Assessment

Schedule adherence shows that electricity markets do not consist of prices alone. They also need roles, deadlines, metering rules and clear responsibilities. The BRP stands between customers, generators, traders, exchanges, and grid and metering point operators. It registers quantities, updates forecasts and balances trades. For remaining deviations, it bears the financial consequences. This becomes all the more important as the system becomes more fine-grained: millions of photovoltaic systems, heat pumps, charging points and battery storage units turn classical power plant dispatch planning into a data-driven coordination of many feeders and consumers. Properly understood, schedule adherence describes neither a perfect forecast nor physical grid operation. It describes the quality of the interface between market planning, measurement and balancing in the system.

Sources

Related glossary entries

Edited by eCMS on 11.11.2026 19:47

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