Solar-plus-storage projects bring together equipment from multiple suppliers. A cable may meet its electrical specification yet still cause installation delays if its connector, terminal orientation or finished length does not match the equipment.
SMA’s DC-coupled hybrid solution combines solar, battery storage and grid-forming capability, with initial availability planned for Germany, the UK and Australia. For EPCs and system integrators, this illustrates why cable interfaces deserve attention early in project design.
The practical starting point is simple: agree on every connection before releasing cable assemblies for production.
1. Define the Connection Boundaries
Start with an approved single-line diagram and an interface schedule covering the PV array, battery system, DC-DC converters where applicable, and power conversion system (PCS).
A DC-coupled architecture does not mean the PV array and battery can simply be connected together. Cable interfaces must follow the selected equipment topology and operating limits.
For each connection, record:
- Equipment and terminal identification at both ends.
- Cable supply and installation responsibilities.
- Connector or lug manufacturer and part number.
- Polarity, pin assignment and protective earth requirements.
- Drawing revision and approval owner.
Include control, communication and auxiliary connections. A missing BMS communication cable can delay commissioning even when the main power cables are ready.
2. Provide Complete Electrical and Environmental Data
An RFQ for a solar battery cable or BESS wiring harness needs more than a nominal voltage and cable size.
| Information | What to specify |
|---|---|
| Voltage | Maximum operating voltage and relevant equipment limits |
| Current | Continuous current, charge/discharge duty and overload conditions |
| Fault conditions | Available fault current and protection clearing requirements |
| Installation | Routing, grouping, enclosure conditions and termination space |
| Environment | Ambient temperature, sunlight, water exposure, chemicals and corrosion conditions |
| Mechanical requirements | Bend radius, movement, strain relief and cable entry dimensions |
| Compliance | Destination market, project specifications and required approvals |
The project engineer should confirm cable sizing against installation conditions, voltage drop, thermal limits and fault withstand requirements. A conductor cross-section alone does not establish suitability.
3. Confirm the Exact Connector Pair
“MC4 compatible” is insufficient as a purchasing specification.
Stäubli warns against mating its PV connectors with connectors from other manufacturers. Physical fit does not establish an approved electrical connection.
Specify the exact mating pair and verify it against the equipment and connector manufacturers’ instructions. Also confirm the permitted conductor size, cable outside diameter, contact selection and assembly tooling.
For battery and PCS terminals, check lug dimensions, stud size, palm orientation, mounting clearances and the equipment manufacturer’s tightening requirements.
Approve connector substitutions before production. An apparently minor component change can affect assembly fit and project acceptance.
4. Freeze Lengths, Branch Positions and Labels
Prefabrication can reduce site assembly work when dimensions reflect the actual installation.
Define how finished length is measured—for example, between connector reference points or terminal-hole centres. Include routing allowances, bend radius, service access and manufacturing tolerances.
For a custom cable assembly, approve:
- Overall length and branch breakout locations.
- Connector orientation and terminal angle.
- Sleeve, protection and strain-relief positions.
- Labels at both ends, matching project drawings.
Where equipment clearances are tight, check a first article or representative assembly before releasing the full batch. This helps identify fit problems while changes are still manageable.
5. Agree on Inspection and Handover Documents
Define acceptance requirements before placing the order.
The documentation package should include approved assembly drawings, the bill of materials, cable and connector specifications, traceability records and agreed inspection results.
Electrical checks should follow the assembly design and equipment instructions. Insulation or withstand testing must use agreed methods, especially where connected electronics could be affected.
Installation teams also need routing instructions, termination requirements and a clear process for reporting deviations.
Plan the Interface Before Ordering the Cable
For DC coupled solar storage projects, cable procurement works best when equipment suppliers, project engineers and assembly manufacturers review the same approved interface information.
Winpower supplies photovoltaic harnesses, energy storage cables and inverter harnesses. Share your connection drawings, electrical requirements, installation environment and mating component details to begin a project-specific cable assembly review.
Post time: Nov-05-2026