Photovoltaic (PV) wire is a single conductor wire used to connect PV panels in solar power generation systems. There are two types of conductors used in PV wire — aluminum and copper. At first glance, lower-cost aluminum PV wire appears to be the logical choice for many solar applications. However, a closer look reveals several factors that can tilt overall costs — and performance — in copper’s favor.
Aluminum and copper PV wire have a lot in common. Both use a cross-linked polyethylene (XLP) insulation rated at either 600V or 1,000/2,000V, and both are flame retardant, sunlight, oil, and gasoline resistant, and direct burial rated.
However, the two wires differ in their conductive properties, as aluminum is only 61% as conductive as copper. As a result, aluminum PV wire must be a larger gauge to provide the same ampacity (maximum current that a conductor can carry without exceeding its temperature rating) as its copper counterpart.
These size and capacity differences have several downstream impacts that can make copper PV wire a more practical and cost-effective choice. These impacts include:
Using more wire. When using aluminum PV wire, contractors will need either more wires or a larger gauge to achieve the same ampacity as copper, which can drive up aluminum’s relative cost. More wire also means larger (or more) conduits, raceways, and box terminals.
Scalability. Project requirements change, and contractors often need to add wiring to support additional solar capacity. Because copper is more space-efficient, enlarging the plant with copper requires less infrastructure (conduit, etc.) than with aluminum PV wire.
Higher labor costs. Containing labor costs is a top priority for EPCs and contractors. And there’s no getting around it — using aluminum PV wire can mean pulling more cable and installing more supporting infrastructure. Depending on the project specifications, the savings achieved by using lower-cost aluminum wire can quickly disappear when additional labor costs are factored in.
Storage and security. When it comes to job sites and theft, out of sight is out of mind. Large reels of aluminum cable are highly visible to thieves and take up more valuable storage space than copper reels.
The benefits of copper PV wire aren’t all related to its size and ampacity advantages. There are other considerations as well:
Potential grounding issues. Proper grounding requires the conductor (in this case, the PV wire) and the grounding lugs to be the same type of metal. Most grounding lugs are made of copper, so using aluminum PV wire may incur the additional expense of retrofitting the grounding lugs. If this retrofit involves soldering, the cost can be even more — aluminum is much harder to solder than copper.
Availability and lead times. Most aluminum PV wire is manufactured offshore. This can create significant supply chain challenges, especially in today’s environment. Copper PV wire, in contrast, is widely available from domestic suppliers and less prone to costly delivery delays.
‘Buy American.’ The recently signed $1.2 trillion infrastructure bill incorporates an ambitious blueprint for solar energy. Suppliers should expect that ‘Made in America’ will be an important selection criterion for many projects. Specifying domestically-produced copper PV wire over imported aluminum may provide bidders with a competitive advantage.
While copper PV wire does offer many advantages, aluminum is not without its benefits. Aluminum wire is lighter and more manageable than copper, and can be easier to install, especially for long-distance runs. Aluminum has a much lower scrap value than copper, making it less attractive to thieves. Finally, in some configurations, the ‘loaded costs’ of aluminum PV wire (including infrastructure and labor) can be less than copper.
As always, design engineers will determine the best PV wire for each specific project. However, when all factors are considered, copper is often the preferred choice.
At Kris-Tech, we work hard to provide you with the best copper PV wire in the business. Our wire is produced in the USA using domestic materials, helping us minimize supply chain issues and offer the best lead times in the industry. And all Kris-Tech wire is manufactured to meet industry standards and undergoes comprehensive in-house testing.
Kris-Tech’s copper PV wire is available in non-standard lengths without cut or reel charges. We also provide custom cable print legends and a wide range of labeling and packaging options.
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