Grid capacity shortage is a defining market characteristic, but creates opportunity for well-positioned BESS projects. A system operator is required to pro-actively seek and grant transport capacity to a party developing a BESS project with the highest priority over other transport capacity requests, provided that (i) the BESS is located in a grid-congestion area (ii) the BESS operator qualifies as a congestion reliever, i.e. a party in respect of which the allocation of transport capacity will result in an increase in the available transmission capacity for other parties and does not lead to an increase in congestion in the system operator’s system (or in the system of another system operator) and (iii) the BESS operator has entered into contractual agreements with the system operator stipulating that it will act as a congestion reliever.

BESS operators generally rely on TDTR contracts to improve their business case. Under current transport tariff structures, a BESS operator pays often significant grid charges because it is charged as an offtaker rather than a feed-in party for which no transport tariff applies. In practice, many larger BESS projects therefore currently rely on TDTR (time-based transport right) agreements offered only by TenneT (the Dutch TSO). Under these arrangements, the user is guaranteed its contracted transport capacity (GTV) for at least 85% of the year, while TenneT may restrict capacity for up to 15% of the year. In return for this flexibility, TDTR users benefit from significantly (50%+) lower transport tariffs for offtake. Dutch industry association Energy Storage NL is advocating for a tariff exemption for storage assets.