Is Aluminium Solar Cable a Viable Alternative to Copper for Utility-Scale PV?

Why the Industry Is Rethinking Conductor Materials

As utility-scale photovoltaic projects grow in size and complexity, the cost of balance-of-system components has come under intense scrutiny. Among these, DC cabling represents a significant portion of total project expenditure. For decades, copper has been the default conductor material in solar installations, valued for its high conductivity, flexibility, and well-understood performance characteristics. However, rising copper prices and advances in aluminium cable technology have prompted engineers and procurement teams to take a fresh look at aluminium solar cable as a credible alternative — particularly for large ground-mounted PV arrays where cable runs can extend over hundreds of metres.

This article examines the technical, economic, and practical dimensions of switching to aluminium solar cable in utility-scale systems, giving project developers the information they need to make an informed choice.

Electrical Properties: Understanding the Conductivity Gap

The most commonly cited drawback of aluminium solar cable is its lower electrical conductivity compared to copper. Aluminium has a conductivity of approximately 61% of the International Annealed Copper Standard (IACS), meaning that to carry the same current as a copper conductor, an aluminium conductor must have a larger cross-sectional area — typically 1.5 to 1.6 times greater. In practical terms, a 35 mm² aluminium cable is roughly equivalent in ampacity to a 25 mm² copper cable.

This size difference has real consequences for conduit fill, cable tray capacity, and connector compatibility. However, for utility-scale DC string cables or inter-row feeder cables where long straight runs are common and space constraints are less critical than in rooftop installations, the larger cross-section is generally manageable. The key is accurate system design from the outset, using proper voltage drop calculations that account for aluminium's resistivity.

Cost Comparison: Where Aluminium Solar Cable Wins

The primary motivation for specifying aluminium solar cable is cost. Aluminium is significantly cheaper than copper both as a raw material and in fabricated cable form. On a per-kilogram basis, aluminium typically costs 60–70% less than copper. Even accounting for the need to upsize the conductor, the overall cable cost for an aluminium alternative is often 30–40% lower than an equivalent copper solution.

For a utility-scale PV plant requiring several hundred kilometres of DC cabling, this difference can translate into savings of hundreds of thousands of dollars. The table below illustrates a simplified cost comparison for a representative feeder cable application:

Beyond cable material costs, aluminium's lower density also reduces transportation and handling expenses — a meaningful advantage when moving large cable drums across expansive project sites.

Technical Challenges and How to Address Them

Aluminium solar cable does introduce engineering challenges that must be carefully managed. Ignoring these risks leads to connection failures, increased resistance, and potential fire hazards. The most critical issues include:

• Oxidation at terminations: Aluminium oxidises rapidly when exposed to air, forming a resistive oxide layer. All aluminium cable terminations must use connectors and lugs specifically rated for aluminium conductors, and anti-oxidant compound should be applied during installation to prevent oxide buildup.
• Thermal expansion: Aluminium expands and contracts more than copper under thermal cycling. Over time, this can cause connections to loosen. Using spring-loaded or self-tapping connectors designed for aluminium, and adhering to correct torque specifications, is essential for long-term reliability.
• Flexibility and bending radius: Aluminium conductors are less flexible than copper. Modern aluminium solar cable uses stranded or compacted aluminium cores to improve flexibility, but installers must still observe the manufacturer's minimum bending radius to avoid conductor damage during pulling and routing.
• Galvanic corrosion: Where aluminium conductors contact dissimilar metals, galvanic corrosion can occur. Appropriate bi-metallic connectors or isolating materials must be used at all transition points.

Standards and Certifications for Aluminium Solar Cable

Not all aluminium cables are suitable for photovoltaic applications. Utility-scale projects require cables that meet recognised PV-specific standards to ensure long-term performance under harsh outdoor conditions, including UV exposure, temperature extremes, and mechanical stress. Relevant certifications to look for include:

• EN 50618 / IEC 62930: The primary European and international standard for photovoltaic installation cables, covering thermal, UV, and chemical resistance requirements.
• UL 4703: The North American standard for PV wire, required for projects in the United States and Canada.
• TÜV and other third-party certifications: Independent testing and certification by bodies such as TÜV Rheinland or Bureau Veritas provides additional assurance of product quality and compliance.

Procurement teams should verify that any aluminium solar cable product carries the appropriate certifications for the project's jurisdiction and that documentation is available for inspection by the authority having jurisdiction (AHJ) or lender's engineer.

Best-Fit Applications: Where to Deploy Aluminium Solar Cable

Aluminium solar cable is not universally superior, but it excels in specific scenarios. Understanding where it adds the most value helps project teams deploy it strategically rather than as a blanket substitution.

DC Combiner Box to Inverter Feeder Runs

These medium-voltage DC feeder cables often span long distances in utility-scale plants. The combination of high current capacity requirements, long runs, and accessible routing in cable trays makes this an ideal application for aluminium. The cost savings are maximised, while the installation conditions allow for the larger conductor size without difficulty.

AC Collection Cables

On the AC side of the plant, from inverters to the medium-voltage transformer, aluminium has an even longer history of use in power distribution. Utility-grade aluminium AC cables are well-established, and the transition to using aluminium solar cable on the DC side represents a natural extension of existing procurement and installation practices.

Where Copper Remains Preferable

For short string cables between solar modules and combiner boxes — where flexibility, small connector sizes, and ease of installation in tight spaces are priorities — copper remains the better choice. The cost differential is smaller at shorter cable lengths, and the practical handling advantages of copper are more pronounced at the module level.

Verdict: A Viable Alternative with the Right Engineering

Aluminium solar cable is a genuinely viable alternative to copper for utility-scale PV projects, provided it is specified, procured, and installed correctly. The cost savings are substantial and well-documented, and modern aluminium cable technology has addressed many of the reliability concerns that historically discouraged its use in solar applications. The keys to success are selecting certified products, using aluminium-compatible connectors and termination hardware, training installation teams on correct handling practices, and designing the system from the start with aluminium's electrical characteristics in mind.

For developers and EPC contractors working on large ground-mounted PV plants, a hybrid cabling strategy — aluminium for long feeder runs, copper for short string cables — often delivers the optimal balance of cost efficiency and installation practicality. As the solar industry continues to drive down the levelised cost of energy, aluminium solar cable deserves a prominent place in the procurement toolkit.