Germany – Construction work – UW Hölderlinstraße

Construction of a new substation in Wiesbaden, Hölderlinstraße

Project description: As part of the planned energy transition of the state capital Wiesbaden, Stadtwerke Wiesbaden Netz GmbH plans to construct a new substation in Hölderlinstraße, Wiesbaden. Overall measure: Construction of a substation, approx. 1850 m² gross floor area, incl. structural facilities, facade, technical infrastructure and outdoor facilities. Reinforced concrete construction with three basement levels and two storeys. The building will be constructed mostly underground.

Dates: Building permit expected by 30.03.2026, to be submitted in December 2025

Start of specialist foundation engineering (already awarded) for excavation pit 02.04.2026

Invitation to tender 14.04.2026

Tender deadline 02.06.2026

Planned contract award by 01.07.2026

Scheduled start of construction 01.09.2026

Completion of construction 21.03.2028

Handover to sw netz for electrical installation 27.06.2028

Tender breakdown: The following lots are part of the contract award:

Lot 1: Building including building services (The specialist foundation engineering for the excavation pit is part of a separate tendering procedure and is therefore not part of this tender)

Lot 2: Electrical systems including cabling

110-kV switchgear in SF6-free design with 6 fields (supply of operating equipment, coordination and installation by AG, ready for connection for AN)

Two 110/20 kV transformers with a capacity of 50/63 MVA (supply of operating equipment by AG, coordination and installation by AN)

20-kV primary switchgear // DSS system air-insulated (supply of operating equipment, coordination and installation by AG, ready for connection for AN)

20-kV star point switchgear // ESS system SF6-free, gas-insulated (supply of operating equipment, coordination and installation by AG, ready for connection for AN)

Two 20-kV E-coils 52-520 A (DB) and 660 A (KB, 2h) (supply of operating equipment by AG, coordination and installation by AN)

One earthing transformer up to 656 A (DB) and up to 660 A (KB, 2h) (supply of operating equipment by AG, coordination and installation by AN)

The 20- and 110-kV protection and control technology will also be supplied (supply of operating equipment by AG, coordination and installation by AN)

AC and DC own-consumption system (fully by AN)

220 V DC battery system (fully by AN)

Lot 3: Landscape gardening consisting of the creation of the outdoor facilities, fence systems etc.