Description
A complete technical guide to solar cable trays for PV projects — covering open tray vs. closed trunking, ZAM steel vs. HDG steel vs. aluminum material selection, perforated base design, section coupling, and mounting on solar racking rails.
Solar Cable Tray Guide: ZAM Steel, HDG Steel, or Aluminum?
#TLDR
- A solar cable tray is a perforated metal channel that routes and protects DC string cables under solar panel rows.
- Two configurations exist: open tray (ventilated, cables visible) and closed trunking (snap-on lid, full UV and weather protection).
- Three material options: ZAM steel (best corrosion resistance, coastal/industrial sites), HDG steel (proven durability, cost-effective, large utility projects), Aluminum (lightest, no rust, premium rooftop and carport installs).
- Sections join end-to-end via splice plates and carriage bolts — simple, fast, and structurally sound.
- Installation mounts directly onto solar racking rails through the perforated base slots.
Table of Contents
- What Is a Solar Cable Tray?
- Open Tray vs. Closed Trunking
- Why the Perforated Base Matters
- The 3 Material Options Compared
- How Sections Couple Together
- Installation on Solar Racking Rails
- How to Choose the Right Specification
- Solar Cable Tray from Solaracks
What Is a Solar Cable Tray?
A solar cable tray is a structured metal channel system that routes, supports, and protects the DC string cables running from solar panels to the string inverter or combiner box. In a commercial or utility-scale PV installation, you can have dozens of DC cable runs spanning hundreds of metres. Without a tray system, those cables become a tangled liability — vulnerable to UV degradation, abrasion against racking steel, rodent damage, and water pooling.
The cable tray solves all of that in one continuous run.
In solar applications, the tray is a C-channel or U-channel profile — a flat base with two vertical side walls bent inward at the top to form return flanges. Those flanges do three things: reinforce the profile against long-span sagging, protect cable insulation from sharp cut edges, and provide the track that a snap-on lid clips over when a closed configuration is required.
Typical dimensions for solar projects:
- Width: 100–300 mm (150–200 mm most common)
- Side wall height: 50–100 mm
- Section length: 2.4–3.0 m per piece
- Material gauge: 1.2–2.0 mm
Accessories complete the system: 90° elbows for directional changes, T-junction pieces where cable runs branch, and end caps to close open tray ends at the inverter entry point.
Open Tray vs. Closed Trunking
Solaracks supplies the same C-channel profile in two configurations. The choice between them comes down to site exposure and cable protection requirements.
Open Perforated Tray (No Lid)
The top of the tray stays open. Cables rest inside the channel, bundled with UV-rated black zip ties threaded through the base perforation slots. The return flanges at the top edge provide structural rigidity without enclosing the cables.
When to use it:
- Installations where the tray runs directly underneath panel rows — the panels act as a natural weather shield
- Ground-mount projects where ventilation is a priority and UV exposure is limited by panel shade
- Sites where quick cable inspection or re-routing is expected during the operational life of the plant
Closed Trunking (Snap-On Lid)
A flat, smooth steel lid clips over the return flanges to create a fully enclosed rectangular profile. The lid is solid and unperforated, blocking UV radiation, bird droppings, debris, and direct rain contact.
When to use it:
- Exposed rooftop installations where cables have no overhead panel shading
- Any site with significant UV, coastal spray, or industrial airborne contamination
- Projects requiring a cleaner aesthetic — the closed trunking reads as a single continuous metal line
- Utility-scale ground-mount installations where long cable runs are fully exposed between inverter blocks
The key advantage of the Solaracks design is that the lid is a separate component — you can order the tray with or without lids, or add lids retrospectively in the field.
Why the Perforated Base Matters
The base of every Solaracks cable tray carries staggered oblong perforation slots arranged in four to five parallel rows running the full length of each section. That perforation pattern handles four distinct engineering functions:
- Drainage: Water that enters the open tray drains immediately through the slots rather than pooling and corroding cable jackets from below.
- Thermal ventilation: DC cables under load generate heat. The open slot pattern allows convective airflow across the cable bundle, reducing operating temperatures and extending cable life.
- Cable tie anchor points: UV-rated nylon zip ties thread through the slots to bundle and secure cables at regular intervals.
- Mounting points: The same slots accept the bolts or clamps that fix the tray to solar racking rails or L-bracket support arms below.
The 3 Material Options Compared
ZAM Steel (Zinc-Aluminum-Magnesium)
ZAM is a mill-applied metallic coating combining zinc, aluminum (11%), and magnesium (3%) directly onto the steel substrate. The alloy produces a fine, uniform micro-crystalline surface — matte, cool silver-grey, with no spangle pattern. When the coating is scratched or cut, the zinc-aluminum-magnesium alloy migrates to the exposed point and forms a dense barrier oxide — a self-healing effect that hot-dip galvanizing does not replicate.
Best for: Coastal installations (within 5 km of the sea), industrial zones, high-humidity tropical climates, projects targeting a 25+ year design life.
HDG Steel (Hot-Dip Galvanized)
Hot-dip galvanizing immerses fabricated steel components in a bath of molten zinc at around 450°C. The zinc metallurgically bonds to the steel surface, producing a thick (typically 85 µm), durable zinc layer with the characteristic spangle crystalline pattern. HDG is the industry-standard specification for utility-scale solar BOS hardware at the most competitive cost per kilogram.
Best for: Utility-scale ground-mount projects in temperate or semi-arid climates, inland sites without coastal or industrial corrosion exposure, large volume orders.
Aluminum
Aluminum cable trays use an extruded or roll-formed aluminum alloy profile (typically 6063-T5 or equivalent). The surface is mill-finished — lighter silver-white, smoother and visually cleaner than either steel variant, with no spangle and no rust risk.
Best for: Carport and canopy installations, commercial rooftop projects with strict roof loading limits, applications requiring zero rust risk, premium aesthetics.
How Sections Couple Together
A single solar cable tray section runs 2.4 to 3 metres. Solaracks sections join via splice plates: flat rectangular metal strips that bridge the butt joint between two tray ends, fastened with carriage bolts — smooth round-head bolts with a square neck that seats flush in the slot, eliminating any internal protrusion that could abrade cable insulation.
The assembled joint sits flush on the interior face, creates a metal-to-metal contact point that maintains earthing continuity, and allows slight angular adjustment where the tray must follow a non-perfectly-straight racking layout.
Installation on Solar Racking Rails
Solar cable trays install on racking structures in three ways:
1. Direct rail mounting (most common on ground-mount) — tray base slots align with the horizontal C-channel or Z-purlin rails of the racking structure. Bolts pass through the base perforation slots and clamp directly onto the rail flange.
2. L-bracket cantilever arms (rooftop and carport) — short L-bracket arms bolt to the racking rail and extend horizontally, with the tray resting on the bracket’s flat face.
3. Trapeze hangers (suspended runs) — threaded rod drops from a cross-beam and supports a horizontal bar under the tray base. Used for longer unsupported spans on large utility projects.
In all three configurations, the cable tray run should be level or with a slight consistent pitch toward a drainage point. The tray is never a structural member — it carries cable mass only.
How to Choose the Right Specification
| Site Condition | Recommended Material | Configuration |
|---|---|---|
| Coastal (within 5 km of sea) | ZAM Steel | Closed trunking |
| Tropical / high humidity | ZAM Steel | Closed trunking |
| Industrial / chemical exposure | ZAM Steel | Closed trunking |
| Inland utility ground-mount | HDG Steel | Open tray (under panels) |
| Commercial rooftop, exposed | Aluminum or ZAM | Closed trunking |
| Carport / canopy (load sensitive) | Aluminum | Closed trunking |
| Large utility, budget-driven | HDG Steel | Open tray |
Solar Cable Tray from Solaracks
Solaracks supplies solar cable trays as part of a complete BOS accessories portfolio — alongside walkways, guardrails, and safety anchors. All three material grades (ZAM, HDG, Aluminum) are available in both open tray and closed trunking configurations, with the full fitting range: 90° elbows, T-junctions, end caps, splice plates, and mounting hardware.
Lead time for standard orders is around 20 days. Engineering support is available for layout design, span calculations, and product selection — at no additional cost.
Request a quote or product specs at solaracks.com
The team turns around quotes and technical data sheets within 24 hours.
