The Z1 is the base structure for the U.S. solar array. It includes two plasma contactors, two DC-to-DC converter units (DDCUs), four control moment gyro (CMG) assemblies, part of one string of the S-band communications system, one Ku-band communications system, primary and secondary power distribution, thermal control system hardware, mechanical interfaces, and EVA/extravehicular robotics (EVR) hardware.

The S-band communications system consists of two redundant strings, each of which comprises three on-orbit replaceable units (ORUs) and two antennas, the baseband signal processor (BSP), the Tracking and Data Relay Satellite System (TDRSS) transponder, and the antenna RF group, which includes a low-gain antenna and a high-gain directional antenna.

The Ku-band system is the primary return link for International Space Station (ISS) video and payload data transmitted in digital format to the ground. The space-to-ground antenna (SGANT) will be relocated and attached to the single-beam boom of the current Ku-band antenna on EVA1.

The Z1 truss assembly has several power distribution components. These include two initialization diode assemblies (IDAs), two secondary power distribution assemblies (SPDAs), two plasma contactor units (PCUs), two DDCUs, and two patch panels.

Several spacewalk aids equip the truss assmebly: Two EVA tool stowage devices (ETSDs), 22 worksite interface (WIF) sockets, 1 flight-releasable grapple fixture (FRGF), 11 trusses, 2 tray launch restraints, numerous standard handholds and handrails, and several custom handles.

The motion control subsystem (MCS) hardware launched as part of the Z1 element includes the CMGs and the CMG assemblies. This hardware will not be activated until Mission 5A, when the GN&C MDM will be activated with the U.S. Lab.

Mechanical interfaces are provided between Z1 and the P6 long spacer on the Z1 zenith face, between Z1 and Node 1 on the Z1 nadir face, between Z1 and PMA-2 on the Z1 forward face, and across a cable tray from the Z1 forward face to the U.S. Lab.

The Z1 truss assembly includes the following elements of the early external active thermal control system (EEATCS): 4 accumulators, ammonia, and 12 quick disconnects and associated plumbing. The accumulators charge the EEATCS with ammonia on orbit, accommodate thermal expansion in the fluid, and maintain the system's operating pressure. The quick disconnects facilitate the connection of ammonia transfer lines between P6 and Z1 and between Z1 and the U.S. Lab.