Public tender for procurement of aFRR balancing capacity and/or balancing energy

The right to participate in the public tender is granted to all Balancing Service Providers that have a valid aFRR Balancing Service Agreement with the Transmission System Operator and have provided the appropriate financial security (deposit or bank guarantee).

For the purposes of the Rules for the Procurement of aFRR and mFRR Balancing Capacity and/or Balancing Energy, September 2026 (HOPS 9/2026), Balancing Service Providers are defined as Bidders.

Bidders submit bids for:

provision of aFRR balancing capacity,
balancing energy from contracted aFRR balancing capacity,
balancing energy from voluntary bids.

A Bidder whose bid for aFRR balancing capacity has been selected for the relevant balancing service provision period is entitled to transfer all or part of its obligation to another Balancing Service Provider.

Procurement process overview:

Tendering for aFRR Balancing Capacity

aFRR product parameters:

Product aFRR R1
Min bal. capacity bid size	1 MW
Activation method	Automatic, via the LFC controller
Bid divisibility (bal. capacity)	Divisible, in 1 MW increments
FAT	≤ 5 min
Direction	aFRR+ R1: (+) increase in delivery to the grid or decrease in withdrawal from the grid;
Direction	aFRR− R1: (−) decrease in delivery to the grid or increase in withdrawal from the grid
Minimum Balancing energy bid	1 MW
Balancing energy bid divisibility	Divisible, in 1 MW increments
Energy Bid granularity	Portfolio, regulation group or regulation unit*

* For regulation units and groups with prequalified balancing capacity equal to or greater than 3 MW, the TSO may require balancing energy bids to be submitted at the individual regulation unit level.
The method for submitting balancing energy bids for new regulation units is defined upon their inclusion in the portfolio of an individual Balancing Service Provider.
If the method for submitting balancing energy bids for existing regulation units is changed at the request of the TSO, the Balancing Service Provider shall be notified at least 30 days in advance.
Upon its own request and subject to the TSO’s prior approval, a Balancing Service Provider may submit bids at the regulation unit level.

aFRR balancing capacity price limits

Price limits for the procurement of balancing capacity are defined as the unit price calculated in accordance with Article 11 and Annex 2 of PoUEES, i.e. as the regulated balancing capacity price for the provision of balancing services by the dominant Balancing Service Provider.

All prices are exclusive of VAT, expressed in EUR/MW/h and rounded to two decimal places.

Products	Direction	Price Limit (EUR/MW/h)
aFRR+ R1	+	21,24
aFRR− R1	−	25,64

Balancing energy price limits

The TSO may prescribe balancing energy price limits, in particular, but not exclusively, in cases where there are significant differences between the offered balancing energy prices and wholesale electricity market prices.

Balancing energy price limits for a Balancing Service Provider holding a dominant position in the balancing services market in the Republic of Croatia are determined in accordance with PoUEES.

All prices are exclusive of VAT, expressed in EUR/MWh and rounded to two decimal places.

Product	Direction	Price Limit (EUR/MWh)
aFRR+ R1	+	500,00
aFRR− R1	−	−500,00

Tendering procedure and timeline for balancing capacity

The aFRR balancing capacity tender covers six four-hour time blocks:

1. 00:00–04:00 (hours 1–4 of day D)

2. 04:00–08:00 (hours 5–8 of day D)

3. 08:00–12:00 (hours 9–12 of day D)

4. 12:00–16:00 (hours 13–16 of day D)

5. 16:00–20:00 (hours 17–20 of day D)

6. 20:00–24:00 (hours 21–24 of day D)

Bid submission period:

• GOT: 00:00 seven (7) days before the delivery day (00:00, D-7)

• GCT: 10:00 on the day preceding the delivery day (10:00, D-1)

• POT: 10:30 on the day preceding the delivery day (10:30, D-1)

aFRR balancing capacity bids are selected using a minimum-cost optimization method (MILP algorithm), as defined in Annex 5 of the Rules for the Procurement of aFRR and mFRR Balancing Capacity and/or Balancing Energy, September 2026 (HOPS 9/2026).

The total required amount of aFRR balancing capacity and/or balancing energy for the tender is published for each individual balancing product through the Balancing Platform as part of the tendering process.

Balancing energy bid submission process

Bidders whose balancing capacity bids have been selected in the tendering process are required to submit balancing energy bids in an amount equal to or greater than the contracted balancing capacity.

A Bidder whose balancing capacity bids has been accepted shall submit preliminary balancing energy bids no later than 14:30 on the day preceding the delivery day (D-1), GCT0.

Bidders whose balancing capacity bids have not been selected may submit voluntary balancing energy bids.

• Balancing energy bid resolution: 1 MTU (15 minutes)

• GOT: 7 days before the individual MTU (MTU – 7 days)

• GCT0: 14:30 on the day preceding the delivery day (14:30, D-1)

• GCT: 25 minutes before the start of the relevant MTU (MTU – 25 min).

Balancing capacity and balancing energy bids shall be submitted electronically via the HOPS IT system – Balancing Platform.

Results of public tenders for aFRR balancing capacity

• Results of public tenders for aFRR balancing capacity for 2024

• Results of public tenders for aFRR balancing capacity for 2025

• Results of public tenders for aFRR balancing capacity for 2026