Firm and flexible

Firm capacity refers to a grid connection that can be utilised at 100% of its rated power throughout the entire year without any congestion-related restrictions.

A flexible connection allows APG to temporarily limit grid usage during periods of congestion that could affect grid stability.

APG calculates hosting capacities using a power transfer distribution factor (PTDF)-based methodology, which evaluates the impact of additional injections or withdrawals on critical grid elements. The analysis is based on the most recent TYNDP data available for the current year. A substation is assigned a hosting capacity of 0 MW (for either generation or consumption) if there is at least one hour in the year where an additional connection would exacerbate an existing congestion or create a new congestion under N-0 or N-1 security conditions. The methodology applies uniformly across the generation, demand, and storage categories. The analysis is static in nature, focusing on steady-state power flow impacts rather than dynamic or short-circuit behaviour. Hosting capacities are published per substation and reflect the firm connection potential, i.e. capacity that can be used without restriction throughout the year. The approach is independent of the grid user profile. The only distinction is between firm connection and flexible connection.

The published hosting capacities reflect the amount of additional power that can be either injected into or drawn from the grid without causing congestion or negatively impacting grid stability. If a firm connection is not feasible – meaning that even for a single hour in the year, an additional connection would compromise grid performance – flexible connection options may still be available. In such cases, APG retains the right to temporarily limit the connection’s power during critical periods to ensure grid security. 

According to Article 50(4a) of Regulation (EU) 2019/943 on the internal electricity market, as amended by Regulation (EU) 2024/1747, TSOs are required to publish information on available grid connection capacities and update this information monthly. The published table provides information on available and requested grid connection capacities, as well as on the possibility of flexible connections to APG’s transmission network. The published values were determined in accordance with the grid compatibility assessment procedure as outlined in our General Grid Conditions. 

At present, no unrestricted grid connection capacities are available in APG’s transmission network. Depending on the specific connection situation, an unrestricted grid connection may be granted – as an exception and subject to a positive grid compatibility assessment – for non-interruptible end consumers who pay grid usage fees in accordance with § 5 para. 1, items 1–7 of the SNE-V 2018. The column “Flexible Connection Possibility” indicates whether a limited (flexible) grid connection may be requested. Such a connection may be granted subject to a positive grid compatibility assessment. According to § 44 para. 1 of the ElWOG, the right to connect to the grid within a distribution network area generally lies with the DSOs. A direct connection to APG’s transmission network is possible only if the relevant DSO waives this right. Exceptions apply to grid users who supply electricity or are to be supplied with electricity at a nominal voltage above 110 kV. In this case, a minimum capacity of 200 megawatts (MW) is required, as stipulated in § 55 para. 7, item 5 of the ElWOG. The published hosting capacity values are indicative only and do not constitute a binding commitment for grid connection. They are based on model-based analyses using the most recent available data and reflect the current state of the transmission system under standard assumptions. Key limitations include:

• Values are updated monthly and may change due to evolving grid conditions, new connection requests, or infrastructure developments.
• The analysis is based on static grid models and does not account for all real-time operational constraints or dynamic behaviours.
• A positive hosting capacity value does not guarantee a firm or flexible connection. Each request is subject to a detailed, case-specific grid compatibility assessment.
• The values refer to the transmission grid only and do not consider potential limitations in the underlying distribution networks.