At a grid-connected battery energy storage system (BESS) site, power cables serve both battery-side DC circuits and AC circuits downstream of the power conversion system (PCS). This article focuses on the AC-side cable network, which carries converted power from the PCS through switchgear and transformers to the collection system and point of interconnection (POI). Each section faces different electrical duties, routing conditions and environmental constraints. GENGU CABLE supports BESS EPC contractors and system integrators with project-specific power and control cable solutions based on single-line diagrams, equipment documentation and installation requirements.
AC-Side Cable Routes in a BESS Project
A BESS AC-side arrangement may follow this path:
PCS → AC switchgear and protection → Transformer → AC collection network → Substation / point of interconnection
Project layouts vary. Some BESS power blocks connect the PCS directly to a dedicated transformer, while others include switchgear, protection equipment or an AC collection bus before reaching the transformer. The cable schedule should identify the actual circuit boundaries shown on the project single-line diagram.
| Cable location | Function in the system | Main selection inputs |
| PCS output route | Carries converted AC power from the PCS to downstream switchgear or transformer equipment | Continuous current, overload duty, grounding, terminal arrangement, route length and installation method |
| Transformer connection | Connects BESS power blocks to the site collection system | Conductor size, insulation, metallic screen, fault duty, sheath construction and route environment |
| Collection network | Aggregates power across BESS blocks toward the substation or point of interconnection | Circuit loading, earthing arrangement, route profile, joint planning, moisture exposure and maintenance access |
BESS projects may also include control circuits for switchgear, protection panels, metering, distribution equipment and auxiliary systems. These circuits are specified separately from the main power feeders and may require different conductor counts, shielding, route separation and fire-performance characteristics. GENGU CABLE’s PVC/XLPE insulated control cables are available in standard, screened, armored, flame-retardant, low-smoke low-halogen and LSZH constructions for applicable control and measurement circuits.
PCS Output Cable Selection
The PCS output route often operates under high continuous loading and may run close to power electronics, switchgear and containerized equipment. Cable selection begins with the PCS documentation and the electrical design for the relevant BESS block.
The output arrangement, maximum operating current, overload profile, available fault current, grounding method, terminal type, cable-entry arrangement and available installation space provide the basis for the cable specification.
| Selection point | Why it matters |
| Conductor material and size | Must support design current, permitted voltage drop, installation conditions, terminal compatibility and fault-duty requirements |
| Insulation system | Must suit the electrical duty, expected operating temperature and technical specification |
| Single-core or multicore construction | Depends on circuit arrangement, cable formation, available space and installation method |
| Short-circuit thermal withstand | The conductor and any metallic screen must withstand the specified fault current for the protection system’s clearing time |
| Metallic screen | May be required by the earthing design, protection study, electromagnetic-compatibility requirements or equipment documentation |
| Outer sheath | Must suit abrasion, moisture, UV exposure, chemical contact, burial or tray installation |
| Termination arrangement | Must match the equipment interface, selected conductor and connection method |
GENGU CABLE offers metallic-screened power cable options for projects whose electrical design calls for screened construction. The screen design, bonding arrangement and relevant earthing requirements should be confirmed in the project documentation.
Routing details should be reviewed before the cable is manufactured. Cable-entry direction, bending space, pulling access and termination clearance can affect both cable construction and installation sequence.
AC Collection Cable Selection
The AC collection network transfers power from individual BESS blocks toward the collector substation, switchgear or point of interconnection. Collection feeders are often longer than PCS output routes and may pass through cable trays, ducts, trenches and direct-buried sections within the same project.
GENGU CABLE provides XLPE power cable options for collection and distribution circuits, with conductor, metallic-screen, armor and outer-sheath constructions configured to suit the electrical design and route conditions.
| Collection-system factor | Effect on cable selection |
| Route length and load profile | Affect permissible voltage drop, energy losses and conductor sizing |
| Continuous current rating | Determines conductor sizing under actual installation and thermal conditions |
| Short-circuit thermal withstand | Requires the conductor and metallic screen, where present, to withstand the specified fault level and clearing time |
| Earthing design | Influences screen selection and bonding arrangement |
| Installation environment | Determines sheath, mechanical protection and external-protection requirements |
| Maintenance strategy | Influences joint-bay location, circuit identification and repair access |
For longer collection feeders, conductor sizing should be checked against permissible voltage drop and project loss targets as well as continuous current-carrying capacity. A feeder may leave an outdoor cable tray, pass through a duct bank and enter a direct-buried section, with each part of the route affecting heat dissipation, sheath selection and mechanical protection.
For underground sections, soil thermal properties, groundwater, drainage and backfill design can affect cable operating conditions over time. Where routes face mechanical risk, the protection method may involve armored construction, ducts, protective covers or other measures defined by the route design and project specification.
Cable Route, Installation and Delivery
Cable selection and installation planning are closely connected. Site conditions affect current-carrying capacity, cable handling, delivery length and the number of joints required along a route.
Before production and delivery, the EPC team and cable supplier should align on:
- Installation method for each cable section
- Cable spacing, grouping and parallel-circuit arrangement
- Ambient temperature, ventilation and solar exposure
- Soil thermal conditions and groundwater exposure
- Pulling path, bend radius and maximum pulling tension
- Pull pits, joint bays, cable-entry points and terminal locations
- Drainage for trenches, pits and underground structures
- Separation between power cables and low-current circuits
- Fire stopping at cable entries, walls and electrical-room boundaries
- Cable drum lengths, site storage conditions and delivery sequence
- Access for testing, inspection, repair and future expansion
Cable drum planning is especially important on long collection routes. Matching drum lengths to the approved pull length can reduce unnecessary joints and simplify installation. Pull pits, joints and terminations should remain accessible after civil works and equipment installation are complete.
Fire Performance and Cable Construction
BESS sites may include outdoor battery pads, PCS skids, electrical rooms, cable trenches, control rooms and enclosed switchgear areas. The required cable construction depends on the installation location, circuit function, applicable regulations and project specification.
| Performance characteristic | Engineering purpose |
| Flame-retardant | Limits flame propagation along cable routes or grouped cable installations |
| Fire-resistant | Maintains circuit integrity for a specified period under defined test conditions |
| Low-smoke | Supports specifications requiring reduced smoke generation during combustion |
| Low-smoke low-halogen | Supports specifications requiring reduced smoke and halogen-related emissions |
| LSZH | Supports specifications requiring low-smoke, zero-halogen material constructions |
Flame-retardant and fire-resistant cables have different functions. Flame-retardant construction helps limit the spread of flame along cable routes. Fire-resistant construction is selected when a project requires a circuit to maintain continuity during defined fire-test conditions.
Where a project specifies fire performance, the relevant test standard, cable location and circuit function should be confirmed before selection. GENGU CABLE offers relevant options across the following cable families:
- PVC insulated power cables with flame-retardant, low-smoke low-halogen and fire-resistant options
- Concentric neutral power cables with flame-retardant and fire-resistant configurations
- Metallic-screened power cables with applicable flame-retardant and fire-resistant constructions
- XLPE power cables for collection and distribution circuits with applicable flame-retardant, low-smoke low-halogen and LSZH constructions
Starting a BESS Cable Inquiry
An initial BESS cable inquiry can begin with the information already available. A short project description, cable schedule, technical specification, estimated quantity or delivery location is often enough to start a discussion.
As the project develops, PCS and transformer data, current and fault-duty requirements, route information, installation method, environmental conditions, required standards and delivery schedule can help refine the cable construction and quotation. Further drawings and technical information can be reviewed during the project discussion.
Share your project details, cable schedule and technical specifications with GENGU CABLE to discuss a customized AC-side power cable and control cable solution for your BESS project.
FAQ
What does AC-side cable selection cover in a BESS project?
It covers PCS output, switchgear, transformer, collection feeder and substation circuits. Battery-side DC circuits are specified separately from the AC-side power network.
Are control cables used in BESS projects?
Control cables are commonly used for protection, measurement, monitoring and control signals serving switchgear, distribution equipment and auxiliary systems.
How is a PCS output cable selected?
Start with PCS data, design current, overload profile, fault duty, grounding arrangement, terminal type, route length and installation conditions.
Why is short-circuit thermal withstand important?
The conductor—and any metallic screen—must be checked against the prospective fault current and the protection system’s clearing time.
How do voltage drop and cable losses affect collection feeders?
Longer collection feeders may require larger conductors to meet voltage-drop limits and project loss targets, even when their current-carrying capacity is sufficient.
Does every BESS project require screened cable?
No. Use screened construction when required by the earthing design, protection study, electromagnetic-compatibility needs, equipment documentation or project specification.
When should armored cable be considered?
Consider armor where cable routes face mechanical risk. The suitable protection method depends on cable construction, installation conditions and project requirements.
