On most solar farm projects, cables get finalized late. By the time they move up the procurement list, string layouts are frozen, trench routes are set, and the construction program has no slack. That is when the same issues keep coming up: DC certifications that do not cover the full BOQ, MV cables with lead times nobody budgeted for, and installation teams on site waiting for datasheets that should have been confirmed months earlier.
These are timing problems, not technical ones. The project teams that avoid them consistently do one thing differently: they treat the cable package as a priority earlier than it feels necessary.
Inside the Array: DC Cables From Modules to Inverter
DC string cables are the most straightforward part of the cable package to specify. They are also where certification gaps show up most often in practice.
Current flows from each panel through DC string cables to combiner boxes, then through feeder cables to the inverters. These cables spend their entire service life outdoors, under continuous UV, wide temperature swings, moisture, and mechanical stress from wind and foot traffic. PV-rated cables are built specifically for this environment, using insulation and jacket compounds rated for long-term outdoor DC exposure and tested to standards such as EN 50618 and IEC 62930.
The procurement problem is rarely about finding a supplier who stocks PV cables. It is about checking whether their certifications actually cover the sizes you need. A certificate can be entirely valid and still only apply to a limited range of conductor cross-sections. If your BOQ includes sizes outside that range, you have a compliance gap that will not surface until an independent inspector or grid operator asks for documentation. Requesting full test reports for each conductor size in your schedule, rather than a single certificate scan, takes just minutes and avoids a much larger problem later.
From Inverter Onward: Where the Cable System Changes
Past the inverter, the cable system becomes something different. AC power cables connecting inverters to step-up transformers, transformers to the MV collection network, and the collection network to the substation fall under power system standards, not PV-specific ones. These are the same cable types used in power stations, airports, and data centres.
They are also where lead times become a project risk. MV collection cables and HV export cables to the grid connection point are not off-the-shelf products. On projects where they get procured on the same schedule as structural steel or civil materials, they become the critical path quietly, without anyone flagging it until trenching is already underway and cables have not arrived.
Design choices made earlier in the project—trench routing, burial depth, how many circuits share a duct—interact with site conditions like local soil thermal resistivity in ways that directly affect how these cables need to be sized. Getting this right requires coordination between the electrical designer, the civil team, and the cable supplier well before the BOQ is locked, not as a post-tender clarification.
How Solar Farm Cables Are Routed Across the Plant
Not all cables on a solar farm are installed the same way, and the installation method affects what you need to specify.
DC string cables run along the module racking, clipped or tied to support rails. They are easy to access but are continuously exposed to the weather. The clips and ties matter more than they look: standard plastic hardware becomes brittle in UV and heat, and failed supports leave cable hanging against sharp frame edges for years before anyone notices.
DC feeders and low-voltage AC cables between inverter skids and MV transformers typically run in conduit or on cable tray. The main concerns are thermal management, circuit separation, and keeping bending radii within limits during installation.
MV and HV cables go underground in trenched ducts with sand bedding and protective covers. Laying below the manufacturer’s minimum temperature or exceeding pulling tension limits during long duct runs can both cause insulation damage that shows no visible sign until the cable is energized. The installation datasheet should be on site and followed before laying starts.
What to Check Before You Commit to a Manufacturer
Price and delivery dominate most cable tender evaluations. Three questions tend to matter more.
Does the certification actually cover your specification?
Certifications can be legitimate and still not cover what you are buying. A supplier may hold a valid type test report for one voltage class or construction type while your drawings specify another. This is a gap that typically surfaces when a grid operator or independent inspector asks for documentation at commissioning. For DC cables, confirm the report covers the PV cable standard your project market requires. For MV and HV cables, check that the voltage class, armor type, and conductor size range in the report match your drawings exactly.
Can the manufacturer support your installation team on-site?
MV and HV cables have installation limits, such as minimum laying temperature, maximum bending radius, and maximum pulling tension. These are easy to overlook on a busy site and hard to detect when breached. Damage to insulation or conductors during installation typically shows no visible sign until the cable is energised. Ask for the installation datasheet with the product submittal, and confirm the supplier’s engineers are reachable during the laying and jointing phase. A damaged joint discovered after backfilling costs far more to fix than the effort of getting this right upfront.
Are lead times built into the program before the BOQ is frozen?
MV and HV cables take time to manufacture, and lead times lengthen when factories are running full. Projects that treat the cable package as a late-stage procurement item regularly find themselves with trenches ready and no cables to lay. Getting lead time confirmations from preferred suppliers before the BOQ is finalized takes one conversation. Done early, while route lengths and quantities are still being refined, it can protect weeks of the construction schedule.
How GENGU Supports Solar Farm Projects
At GENGU CABLE, we manufacture XLPE-insulated power cables across the full voltage range, with particular strength in the medium- and high-voltage cables that connect solar farms to the grid. Our cables have been used in the Google/Alphabet AI data center, Siem Reap-Angkor International Airport in Cambodia, and infrastructure for the Asian Games—projects where cable performance and documentation are held to the same standard as any other safety-critical component.
For project teams with requirements across multiple cable categories, our engineering team can advise on specifications and direct sourcing enquiries accordingly. On active projects, our involvement typically covers three stages:
- Before the BOQ is finalized: Our engineers review cable lists and single-line diagrams against applicable standards and flag specification gaps or construction types that need adjustment for local grid requirements or site conditions.
- During production: Factory inspections can be arranged, test reports ship with each batch, and our logistics team works against the construction program to time MV and HV deliveries to trenching windows.
- Through commissioning: Our technical support covers installation questions on bending radii, laying temperatures, and jointing, as well as documentation packages for grid operators and lenders’ independent engineers.
To get a review of your cable schedule and specification, share your single-line diagram and cable list with our team via the contact form.
