New OKTE, a.s. Operation Order (effective from September 30th 2025)
15-Minute MTU in SDAC was Implemented

FAQ

OKTE, a.s. Operation Order is placed on the website legislation

OKTE, a.s. as nominated electricity market operator

OKTE, a.s. as nominated electricity market operator

The organised short-term cross-border electricity market in Europe is a wholesale pan-European electricity market. In this market, producers, consumers, and suppliers from all coupled countries can offer electricity for sale and demand electricity for purchase, and it is a short-term market, i.e., trades will be concluded from the day before the day of delivery of electricity (day-ahead market; SDAC) to 30 minutes before the supply of electricity (intraday market; SIDC).

To organizing the short-term cross-border electricity market, OKTE operates the XMtrade®/ISOT platform, which is used to receive orders, match orders, and evaluate the organized short-term cross-border electricity market.

The day-ahead market is auction-based daily cross-border trading as part of an organised short-term cross-border electricity market, with trading generally taking place 1 calendar day before the trading day.

The intraday market is the continuous intraday cross-border trading as part of the organised short-term cross-border electricity market.

Intraday auction market is intraday trading as part of organized short-term cross-border electricity market, whereby trading is organized in the form of three auctions (Intraday Auction) where IDA1 and IDA2 are executed 1 calendar day prior the delivery day and IDA3 is executed on the delivery day.

General information on the publication of market information

General information on the publication of market information

The results are published in a 15-minute trading interval from the delivery date of 1.10.2025. OKTE, a.s. publishes daily at no later than 15:30 on the following trading day:

  • offered purchase and requested sale (MW)
  • traded purchase and sale (MW)
  • difference between purchase and sale = import/export (MW)
  • electricity price in the Slovak trading area (€/MWh)
  • aggregated purchase and sale curves with indication of traded quantity
  • price indices (base, peak, off-peak) - arithmetic average of prices
  • foreign flows with SR–CZ, SR–PL, SR–HU (both ways, in MW)

In case of technical problems, the results may also be published in a 60-minute trading interval. For more information on the exception, see the section Exceptional situationsfor the day-ahead market.

 

OKTE, a.s. publishes the following information separately for each 15-minute trading period and 60-minute trading period after the close of the trading period on the intraday continuous market:

  • total purchase and sale (MW)
  • traded purchase and sale (MW)
  • difference between purchase and sale (MW)
  • weighted and average price of trades (€/MWh)
  • volume of matched orders (MW)

OKTE, a.s. publishes for each evaluated auction within the intraday auction market in accordance with the data disclosure:

  • total purchase and sale (MW)
  • traded purchase and sale (MW)
  • purchase – sale difference (MW)
  • weighted average price of trades (€/MWh)
  • volume of matched orders (MW)
  • aggregated purchase and sale curves with indication of traded quantity

OKTE, a.s. provides 3 types of licenses

  • License A – Internal Use – Data may only be used for the participant’s internal purposes without the possibility of publication or further sharing. Market participants automatically have this type of license upon signing the Agreement on Access and Conditions of Participation in the Organized Short-Term Cross-Border Electricity Market.
  • License B – Simple Redistribution – Data may be used for internal purposes and market data may be made available to third parties on a limited basis. It is not permitted to allow their downloading or further distribution to third parties.
  • License C – Full Redistribution – The participant may process and further distribute the data in any way.

Yes, but only in the case of license B or C. With license A, distribution is prohibited - the data is intended for internal use only.

Yes, OKTE, a.s. has the right to verify whether the licensed entity uses the data in accordance with the terms.

General questions on the terms and conditions for participation in the organised short-term cross-border electricity market

General questions on the terms and conditions for participation in the organised short-term cross-border electricity market

To get access to the XMtrade®/ISOT system, a market participant in an organised short-term cross-border electricity market must have:

  • valid and effective Agreement on Settlement of imbalances
  • valid and effective Agreement on the Access to and the Conditions for Participation in the Organized Short-Term cross-border Electricity Market

The contract shall come into effect after payment of the annual fixed payment, submission of the SEPA B2B direct debit mandate and the deposit of the financial guarantee. In order to get access to the XMtrade®/ISOT system, it is necessary to fill in the Request for creation/change of a user account to the XMtrade®/ISOT system and to send this request to the nominated electricity market operator, OKTE, a.s., at the address certificate@okte.sk.

The request for access to the ISOT system can be found on the OKTE, a.s. website under the Short-Term Market part in the documentation section.

According to the relevant Decision of RONI (ÚRSO), price is specified for:

  • annual fixed fee for organizing and evaluation of the organized short-term cross-border electricity market,
  • tariff for organizing and evaluation of the organized short-term cross-border electricity market, applicable for electricity purchased and sold on the organized short-term cross-border electricity market.

The amount of the fees is specified in the decisions of RONI (Regulatory Office for Network Industries) in the section Legislation

The financial guarantee is represented by the available financial guarantee of the DFZ (available financial security).

A market participant in an organised Short-Term Cross-Border Electricity Market may secure a DFZ by one or a combination of the following options:

  • by depositing cash into the bank account of OKTE, a.s,
  • by providing a bank guarantee issued by a bank licensed in the Slovak Republic with a long-term credit rating of BBB+ (S&P) or Baa1 (Moody's) or by the Slovak Guarantee and Development Bank or EXIMBANKA SR with a validity period of at least 12 months in the Slovak language.

Further information is described in the Operation Order of OKTE, a.s.

The activities of a Short-Term Market Participant may give rise to financial guarantee towards Settlement of Imbalance. For this purpose, the market participant as subject of imbalance shall provide financial guarantees to the Subject of Settlement. For more information, please refer to the Imbalance settlement FAQ.

 

The Short-Term Market Participant determines the amount of the DFZ according to its expected orders on the organised Short-Term Cross-Border Electricity Market from which the financial obligations for the Short-Term Market Participant arise and the size of the expected financial obligations resulting from the settlement of the organised Short-Term Cross-Border Electricity Market and the settlement of the Short-Term Market Participant's obligations to OKTE, a.s. resulting from this settlement, but at least in the amount of €10,000. Towards OKTE, a.s., the placing of the order shall require financial guarantee equal to the largest possible payment, including VAT, which the market participant would have paid to the OKTE, a.s. in the case, that the order would have been fully traded.

The available financial guarantee (DFZ) of a Short-Term Market Participant shall be calculated according to the following formula:

                             DFZ(ÚT)=DÚ(ÚT)+∑(BZ∈ÚT)BZ-NP(ÚT)+NZ(ÚT)-FOO(ÚT)

whereby

DFZ(ÚT) =       is market participant's available financial guarantee (EUR),

DÚ(ÚT) =         is balance of market participant´s funds placed on deposit account as a financial guarantee of orders towards the short-term cross-border electricity market organizer (EUR),

 BZ =                is a sum of bank guarantees (EUR) (bank guarantee valid for less than 30 days not continuously followed by another bank guarantee shall not be taken into consideration),

 NP(ÚT) =        are unpaid assets of the short-term cross-border electricity market organizer towards the market participant (EUR) (assets of the short-term cross-border electricity market organizer towards the market participant not paid in the time of calculation of the DFZ),

NZ(ÚT) =        are unpaid liabilities of the short-term cross-border electricity market organizer towards the market participant (EUR) (liabilities of the short-term cross-border electricity market organizer towards the market participant not paid in the time of calculation of the DFZ),

FOO(ÚT) =      is financial amount of the market participant's orders placed for the following business day (EUR).

Further information can be found in the Operation Order.

If the Short-Term Market Participant has not paid OKTE, a.s. by due date an obligation in connection with the Agreement on the Access to and the Conditions for Participation in the Organized Short-Term cross-border Electricity Market or the Agreement on Settlement of imbalances, OKTE, a.s. is authorised to use the financial guarantee of the Short-Term Market Participant for the payment of the incurred liabilities.

The Short-Term Market Participant will be informed of the use of the financial collateral no later than on the first business day following the day on which the financial guarantee was applied. Non-payment of a due advance prescription within its due date shall also be considered as an unpaid liability to OKTE, a.s.

The financial guarantee must cover the financial volume of submitted orders that have not yet entered the matching process and the financial volume of submitted orders that have been successfully matched.

A market participant adjusting its trading position:

  • may cause the amount of its liabilities to OKTE, a.s. to be higher than its DFZ financial volume, in this case it is necessary for it to replenish its financial guarantee to the extent, that it covers all of the Short-Term Market Participant's liabilities to OKTE, a.s.,
  • may cause the amount of its liabilities to OKTE, a.s. to be lower than its DFZ; in this case, the Short-Term Market Participant may request in writing that the DFZ will be reduced to a level, that covers all of the Short-Term Market Participant's assets. The request for the return of part of the financial guarantee is available on the website under Short-Term Market - Contracts.

In the day-ahead market a sell order and a buy order is validated against financial guarantee:

  • immediately, if the order was placed after 00:00 a.m. on the day before the relevant business day, or on the relevant delivery day.
  • from 00:00 a.m. on the day before the relevant business day, if the order has been placed two or more days ahead. The checking of the financial guarantee is done again after the gate closure time (day-ahead).

In the intraday market a sell order and a buy order is validated against the financial guarantee immediately.

General questions on trading conditions on the organised cross-border electricity market

General questions on trading conditions on the organised cross-border electricity market

A Short-Term Market Participant has the right to place any number of sell orders and any number of buy orders.

No, a Short-Term Market Participant can only place sell orders and buy orders for himself.

The order could be rejected as immediately as the order is placed due to invalid values of quantity and price in the order or due to insufficient financial guarantee. Rejection during advance ordering is due to insufficient financial guarantee. A rejected order will not be traded. In case of entering incorrect values within the allowed values of quantity and price and executing such an order, OKTE a.s. is not liable for property loss, since the Short-Term Market Participant is responsible for the entered data and such orders cannot be claimed.

Day-ahead market

Day-ahead market

Market participants can submit buy or sell orders within the day-ahead market until the deadline for submission at 12:00 (noon) of the calendar day preceding the trading day.

Yes, in this case the Short-Term Market Participant will be informed via relevant notification in the XMtrade®/ISOT.

Order matching is done using the day-ahead market algorithm. The organisation of order matching by the daily market algorithm depends on the matching mode. A description of the daily market algorithm depending on the matching mode is described in the Operational Order in Annex 1. Trading on the daily market platform is based on the principle of implicit auction.

More in-depth description is described in the document Description of the function of the EUPHEMIA order matching algorithm, which is published on the OKTE, a.s. website in the Documentation section.

Market participant can submit orders within following products:

  • Hourly products:
    • standard hourly order with a period length of 60 minutes
  • 15-minute products:
    • standard order with a period length of 15 minutes
  • Hourly block products:
    • simple (profile) block order with a period length of 60 minutes,
    • linked block order with a period length of 60 minutes,
    • flexible hourly block order,
    • exclusive group of simple block orders with a period length of 60 minutes.
  • 15-minute block products:
    • simple (profile) block order with a period length of 15 minutes,
    • linked block order with a period length of 15 minutes,
    • flexible block order for one period with a period length of 15 minutes,
    • exclusive group of simple block orders with a period length of 15 minutes.

Detailed description of individual products is available in Operational Order of OKTE, a.s.

An exception may occur in the event of an exceptional situation.

Amount is submitted in MW and price is submitted in €/MWh.

Standard order is product in XMtrade®/ISOT.

Within a standard order, a maximum of 25 blocks can be used per trading period. This means that a market participant may simulate a curve for each trading period using up to 25 points, each defining the electricity volume and the price at which the participant is willing to buy or sell that electricity. The prices indicated in the blocks of the sale order must be placed in ascending order and prices in the blocks of purchase order must be placed in descending order. Within hourly products and 15-minute products, individual trading periods can be accepted separately. First block of the standard order provides market participant with the possibility of using the performance divisibility attribute. Performance divisibility is attribute, which determines whether it is possible to divide the volume of electricity when matching an order (whether the volume may be reduced, whether only a part of the offered volume may be purchased).

Yes, in certain cases a so-called paradoxically rejected 60MTU order may occur. These situations arise due to the optimization of the overall market welfare. If such an order were to be accepted, other orders would have to be rejected, which would reduce the total welfare. For this reason, the EUPHEMIA algorithm does not allow their subsequent acceptance.

Simple order is product in XMtrade®/ISOT. It is classified as block product.

Within a simple block order, a Short-Term Market Participant can define different quantities for any trading periods, with the order containing exactly one block. The Short-Term Market Participant enters a price that covers all trading periods.

Linked order is product in XMtrade®/ISOT. It is classified as block product.

Linked order is simple order, which has assigned parent block order, which acceptance is condition for possible matching of given linked order.

There can be a maximum of 7 orders within a group of linked orders. Up to 3 orders can be defined under a parent order, and each child order can have only 1 parent order defined. Block orders can be linked into a maximum of 3 levels, with the first level always being a simple block (profile) order.

Linking orders into a group is only possible for orders with the same direction (buy/sell) and only for orders with the same trading period length.

Flexible block order is in XMtrade®/ISOT classified as block product.

The Short-Term Market Participant may, within a flexible block order for one period within hourly block products or 15-minute block products, define the quantity and limit price for 1 indefinite trading period within all trading periods of a given trading day. The resulting trading period will be determined by the daily market evaluation algorithm according to the order matching rules defined within Annex 1 of the Operational Order of OKTE, a.s.

Exclusive block order is in XMtrade®/ISOT classified as block product.

A Short-Term Market Participant can define at least 2 and at most 8 single orders within an exclusive order, while the daily market evaluation algorithm determines only one order that can be traded. Orders placed within one exclusive group must have the same trading period.

A Short-Term Market Participant can place single and block orders through XMtrade®/ISOT as follows:

Yes, a Short-Term Market Participant has the right to modify or remove an existing order in connection with a change in quantity or price for a particular trading period, or weighted average price in the case of block products, up to the order acceptance deadline of 12:00 (noon) on the day prior to the day of delivery. A modification of the original order replaces the original version of the order.

Each placed or modified order is validated at:

  • compliance with the required trading resolution of the trading period,
  • compliance with the correct specification of the power divisibility condition within selected trading periods of the first block, which can only be defined for standard orders within hourly products and 15-minute products, compliance with the assignment of electricity quantity and price in at least one trading period of the block,
  • compliance with the paired entry of the quantity of electricity and the price, or weighted average price, in the trading period of the order,
  • compliance with the minimum amount of electricity in a trading period (0.1 MW),
  • compliance with the maximum amount of electricity in a trading period (99 999 MW) ,
  • compliance with the minimum price (-500 €/MWh),
  • compliance with the maximum price (4 000 €/MWh),
  • compliance with the ascending price trend for standard sell orders within hourly products and 15-minute products and a downward price trend for standard buy orders within hourly products and 15-minute products,
  • specific validations to ensure the correct specification of hourly block products and 15-minute block products,
  • the current status of the financial guarantee (DFZ)

The result of the day-ahead market algorithm is the resulting price in the trading area and the trading position of individual market participants (traded electricity volume). The marginal price is different for each trading area and trading quarter-hour separately.

The marginal price is equal to or less than the price of the last accepted demand. The traded volume of electricity is determined by the intersection of the supply curve and the demand curve.

Information on exceptional situations

Information on exceptional situations

Order matching takes place in fully coordinated matching, in which all trading areas within the Single Day-Ahead Coupling (SDAC) are matched. In case of technical problems, local matching may be used, in which the Slovak trading area is matched separately by the algorithm for the separate matching mode (Annex No. 2 of the Operational Order of OKTE, a.s.)

Before starting this mode, Short-Term Market Participants are informed about this event and order reception is open in order to provide the opportunity to correct their orders in view of the situation. Before opening order reception and after closing order reception for the separate matching mode, all existing valid block orders of the exclusive group type and orders with a period length of 15 minutes will be invalidated. The daily market evaluation algorithm for the separate matching mode only supports orders with a period length of 60 minutes.

A Short-Term Market Participant should be prepared in extreme cases to:

  • place orders only in the 60-minute trading period for a given trading day,
  • process the daily market evaluation also in the 60-minute trading period for a given trading day,
  • process results only in the 60-minute trading interval in a given trading day,
    • the time range in the API interface between deliveryStart and deliveryEnd can also be 60 minutes,
    • results in exports will also be available in the 60-minute trading periods for a given trading day,
    • analyze matching curves in the 60-minute trading period.
Intraday continuous market

Intraday continuous market

All tradable products on the intraday market are the Limit Order type. A Limit Order is an indication of an order that is tradable at a price equal to or higher (sell) or at a price equal to or lower (buy) than its limit price condition.

The intraday market consists of the following tradable products:

  • simple orders with a period length of 60 minutes,
  • simple orders with a period length of 15 minutes,
  • block orders covering 2 or more trading periods with a period length of 60 minutes.

Simple orders apply to a single trading period. Simple orders can be of type Limit Order or Iceberg Order.

  • Limit Order is executed when a market price equal to or better than the limit price set by the market participant is available. The participant may choose whether the order should be executed immediately in full, partially, or remain in the system pending a suitable opportunity.
  • Iceberg Order works like a limit order, but its total volume is not displayed at once. Instead, it is gradually revealed and matched in smaller portions until the full volume is executed.

Yes, but only if the order has not yet been traded.

A Short-Term Market Participant can place single or more and block orders through XMtrade®/ISOT as follows:

  • via the order form in XMtrade®/ISOT,
  • by importing an xlsx/XML file,
  • through automatic data exchange.

The volume is indicated in MW and the price is indicated in €/MWh.

Order indications are attributes, that a Short-Term Market Participant can assign to simple orders. Simple orders refer to one trading period only.

The following order indications are defined in the XMtrade®/ISOT system:

  • IOC (Immediate or Cancel) - a simple order is paired immediately and can be partially traded.
  • FOK (Fill or Kill) - a simple order is paired immediately and must be traded in full,
  • AON (All or Nothing) - the block order must be traded in full.
  • Without indication – simple order is available for pairing until its expiry date.

Block orders are automatically assigned AON volume indivisibility.

Each placed or modified order is validated at:

  • compliance with the correct trading period resolution,
  • compliance with the paired entry of the electricity quantity and price within the order,
  • compliance with the minimum amount of electricity (0.1 MW),
  • compliance with the maximum amount of electricity (999 MW),
  • compliance with the minimum price for 1MWh (-€9 999),
  • compliance with the maximum price for 1 MWh (€9 999),
  • status of financial guarantee towards OKTE, a.s.,
  • Iceberg Order – control over the minimum visible quantity (5 MW) and the maximum price step (5 EUR/MWh).

Order matching is done using an intraday market algorithm. The organisation of order matching by the intraday market algorithm depends on the matching mode. A description of the intraday market evaluation algorithm depending on the matching mode is described in the Operational Order of OKTE, a.s.

The time window for the regular service outage is from 17:00 to 21:00 every Tuesday.  In the event that trading on the intraday continuous market is suspended, the Short-term Market participant is notified via XMtrade®/ISOT.

Intraday auctions

Intraday auctions

The intraday auction market is organised trough three intraday auctions with different orderbook gate closure time for placing orders on the same trading day with different delivery periods. Each intraday auction is identified by a unique identifier and allows trading for different intervals of trading periods as follows:

  1. The auction with identifier IDA1 allows trading for all trading periods of the relevant delivery day, whereby closure time for placing orders is 15:00 on the day before delivery day.
  2. The auction with identifier IDA2 allows trading for all trading periods of the relevant delivery day, whereby closure time for placing orders is 22:00 on the day before delivery day.
  3. The auction with identifier IDA2 allows trading for trading periods from 12:00 to 24:00 of the relevant delivery day, whereby closure time for placing orders is 10:00 on the delivery day.

No, in the case of intraday auctions, the gate closure for order submission is not postponed.

Order matching is done using the intraday auction market algorithm. The organisation of order matching by the market algorithm depends on the matching mode. A description of the daily market algorithm depending on the matching mode is described in the Operational Order in Annex 1. Trading on the intraday auction market platform is based on the principle of implicit auction.

More in-depth description is described in the document Description of the function of the EUPHEMIA order matching algorithm, which is published on the OKTE, a.s. website in the Documentation section.

Market participant can submit orders within following products:

  • 15-minute products:
    • standard 15-minute order,
  • block product:
    • simple block order.

Amount is submitted in MW and price is submitted in €/MWh.

Standard order is product in XMtrade®/ISOT. It is classified as a 15-minute product.

Within the standard order market participant can trade 96 periods (92/100 in case of transition to CEST/CET) of one business day in a way, that for every business period maximum of 25 blocks defining amount and price of electricity is possible. The prices indicated in the blocks of the sale order must be placed in ascending order and prices in the blocks of purchase order must be placed in descending order. Individual trading periods can be accepted (traded) separately. First block of the standard order provides market participant with the possibility of using the performance divisibility attribute. Performance divisibility is attribute, which determines whether it is possible to divide the volume of electricity when matching an order (whether the volume may be reduced, whether only a part of the offered volume may be purchased).

Simple block order is product in XMtrade®/ISOT. It is classified as block product.

Within standard order market participant can place any amount for any trading period, while simultaneously submit price, which is equal for every trading period. Simple order consists only of one block which consists of 96 trading periods, when transitioning to CEST, business day is 92 trading periods, while when transitioning to CET, business day is 100 trading periods.

A Short-Term Market Participant can place single and block orders through XMtrade®/ISOT as follows:

  • via the order form in XMtrade®/ISOT,
  • by importing an xlsx/XML file,
  • through automatic data exchange.

Yes, a Short-Term Market Participant has the right to modify or remove an existing order in connection with a change in quantity or price for a particular trading period or weighted average price in the case of block products, up to the order acceptance deadline order book gate closure time. A modification of the original order replaces the original version of the order.

Each placed or modified order is validated at:

  • compliance with the required trading resolution of the trading period,
  • compliance with the correct specification of the performance divisibility condition within the selected trading periods of the first block, which can only be defined for standard 15-minute orders,
  • compliance with the assignment of electricity quantity and price in at least one trading period of the block,
  • compliance with the paired entry of the quantity of electricity and the price, or weighted average price, in the trading period of the order,
  • compliance with the minimum amount of electricity in a trading period (0.1 MW),
  • compliance with the maximum amount of electricity in a trading period (99 999 MW) ,
  • compliance with the minimum price (-9 999€/MWh),
  • compliance with the maximum price (9 999€/MWh),
  • compliance with the ascending price trend for 15-minute standard orders for sales and the descending price trend for standard orders for purchases,
  • specific validations to ensure the correct specification of block products,
  • the status of the financial guarantee (DFZ)

The result of the intraday auction algorithm is the resulting price in the trading area and the trading position of individual market participants (traded electricity volume). The marginal price is different for each trading area and trading period separately.

The marginal price is equal to or less than the price of the last accepted demand. The traded volume of electricity is determined by the intersection of the supply curve and the demand curve.

Test Environments

Test Environments

OKTE, a.s. as nominated electricity market operator offers market participants the opportunity to test communication and the web interface through two test environments.

OKTE, a.s. as nominated electricity market operator offers market participants the opportunity to test communication and the web interface through two test environments.

OKTE, a.s. operates two test environments of the XMtrade®/ISOT system:

  • SANDBOX – This environment contains the production version of the XMtrade®/ISOT system, allowing market participants to simulate real conditions and verify the functionality of their systems.
  • TEST – This environment is intended for pre-production versions of the XMtrade®/ISOT system, where participants can test new features and updates before deploying them to the production environment.

SANDBOX – This environment is available continuously, except during periods reserved for regular maintenance.

TEST –  This environment is available to market participants only during organized testing in the case of significant system, communication, or web interface changes. OKTE, a.s. informs market participants about organized testing through announcements, banners, and system notifications. Market participants will be invited to participate in such testing.

To get access to the testing environments of XMtrade®/ISOT system, a market participant in an organised short-term cross-border electricity market must have:

  • valid and effective Agreement on Settlement of imbalances
  • valid and effective Agreement on the Access to and the Conditions for Participation in the Organized Short-Term cross-border Electricity Market

The deployment of the production version of the XMtrade®/ISOT system to the SANDBOX environment always takes place during working hours on the day following the deployment of a higher version of the ISOT system to the production environment.

The deployment of the production version of the XMtrade®/ISOT system to the SANDBOX environment always takes place during working hours on the day following the deployment of a higher version of the ISOT system to the production environment.

Information on available financial security is updated once a month from the production XMtrade®/ISOT system, usually after the 20th day of the calendar month. If you need to adjust the amount of financial security, please contact us at market@okte.sk.

Yes, nominations from short-term markets are automatically sent to the SANDBOX test environment of the XMtrade®/ISZO system. In the case of the TEST environment, nominations are sent to the TEST environment of the XMtrade®/ISZO system.