​Automatic Frequency Restoration Reserve (aFRR) is Germany's largest frequency response market. For batteries, it offers two revenue streams in one product: a capacity payment for holding megawatts in reserve, and an energy payment when the TSOs activate them. For a full primer on the market, read aFRR explained: Germany's biggest ancillary services opportunity.

Capacity prices are falling. The daily marginal price for positive aFRR (the highest accepted bid in each auction) has averaged €15/MW/h so far in 2026, 35% below the same period of 2025, as more prequalified batteries compete. But that average is a poor guide to revenue: half of all negative blocks clear below €5/MW/h, while single blocks have had bids cleared above €2,000/MW/h.

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Ko can query aFRR history from January 2020

• Capacity auction prices: daily marginal, average, and minimum clearing prices for all twelve POS/NEG 4-hour block products, including offered and allocated volumes, January 2020 to present.
• Capacity auction demand: tendered demand per product and per TSO control area, including gate timings, January 2020 to present.
• Capacity auction bids: every anonymised accepted bid in the capacity auction, with its price and its offered and allocated volumes, across the German, Austrian, and Czech country blocks, January 2020 to present.
• aFRR energy demand: the volume of aFRR energy bids the TSOs tender for in the energy auction, not the energy actually delivered, from November 2020, in quarter-hourly products since Germany joined PICASSO in June 2022.
• Activated aFRR volumes: the energy actually delivered, as quarter-hourly upward and downward activations, Germany-wide and per TSO control area, January 2020 to present.
• Cross-border aFRR energy activation prices: ENTSO-E activated aFRR energy prices for the DE-LU zone up to PICASSO accession in June 2022, and for neighbouring aFRR markets to the present.

aFRR is procured in daily auctions, in two separate markets

German aFRR restores system frequency automatically within five minutes of a deviation: the TSO sends a setpoint signal straight to the asset's control system, with no manual instruction. Providers must start responding within 30 seconds and reach full output within five minutes. The four German TSOs (50Hertz, Amprion, TenneT, and TransnetBW) procure it jointly through regelleistung.net, in a market coupled with Austria and the Czech Republic.

Procurement splits into two separate auctions: one for capacity, one for energy. The capacity auction runs daily, one day ahead of delivery. Providers bid to hold capacity across six 4-hour blocks in two directional products: positive (upward) and negative (downward) reserve. Successful bids earn a capacity price whether or not they are activated. It has been quoted in €/MW/h since December 2021; earlier auctions priced the full 4-hour block, so unconverted pre-2022 prices look four times higher.

The energy auction then determines who actually delivers. Since 22 June 2022, aFRR energy has been procured in quarter-hourly products and activated through the European PICASSO platform, which merges bids across participating TSOs. Bids for each quarter-hour close 25 minutes before delivery. Winning does not mean activating: a successful bid enters the merit order for that 15-minute period, and PICASSO activates bids from cheapest upward whenever the system needs aFRR energy during it. Winning capacity providers must also offer into the energy auction, but only activated bids earn the energy price. An accepted energy bid that is never called delivers nothing and earns nothing.

Batteries suit aFRR well. They respond in seconds, and with charging and discharging available, they bring double the depth to this market compared with a generation unit. But the capacity auction settles pay-as-bid: a provider earns its own bid price, not the clearing price. Knowing when blocks clear high, and how often, is what separates a well-priced bid from a cheap one that wins the auction but leaves money on the table.

How to analyse German aFRR data with Ko

The examples below are real Ko sessions. Each prompt was asked in the live product; Ko generated the SQL, queried the data, built its own chart, and wrote the interpretation. The Output sections condense Ko's actual answers, and the embedded charts are built from the same underlying data.

Click any prompt to open Ko and ask it yourself. Results will reflect the latest available data.

Try asking Ko: which 4-hour blocks paid the most for aFRR capacity over the last twelve months, split by direction?

The 12:00-16:00 block commands the highest aFRR capacity price in Germany, but only for downward regulation.

Negative aFRR is a midday product. The 12:00-16:00 block averaged €57.36/MW/h marginal over the last twelve months, nearly three times the next-highest downward block (08:00-12:00 at €36.89/MW/h) and roughly 24 times the €2.44/MW/h of the 20:00-24:00 block.

Positive aFRR pays at the ramps, and the morning pays more than the evening. The 08:00-12:00 block averaged €47.07/MW/h and the 16:00-20:00 block €35.60/MW/h, while the cheapest window, 00:00-04:00, averaged €4.48/MW/h.

The marginal price is not what most providers earn. Capacity-weighted average prices run lower (€41.27/MW/h for the midday downward block against its €57.36/MW/h marginal) because cheaper bids are accepted first.

Why does midday downward capacity cost so much? The driver sits on the supply side; the TSOs tender broadly flat volumes across blocks. At midday, thermal plants sit offline or at minimum generation, so they have no output left to turn down. Offering negative reserve means deliberately running higher than the market would otherwise pay them to, and the capacity price compensates that lost margin.

The same supply squeeze explains why the morning beats the evening for positive reserve. Through 08:00-12:00, solar floods in and pushes thermal units down towards minimum load or offline altogether, so a unit offering upward headroom has to stay online, part-loaded, through hours when running barely pays, and its capacity bid must recover that cost. By 16:00-20:00 the evening fleet is starting up for the demand peak anyway, so more units are available to provide cheap headroom.

Batteries still commit capacity to the cheap overnight blocks, because overnight wholesale spreads are thin and aFRR capacity revenue often beats the alternative. But do not read the bid stack as pure opportunity cost. That is how a mature market prices, once competition forces every megawatt to bid what it could earn elsewhere. Germany is not there yet: batteries are still bidding against thermal units whose cost of providing aFRR is far higher, so a battery can undercut the thermal bid and still clear well above its own opportunity cost. That premium only competes away when batteries are bidding against batteries at scale.

Try asking Ko: plot the aFRR capacity auction results for 24 April 2026 as a bar chart, block by block, split by direction