New research presented by Arizona State University (ASU) and utility-scale photovoltaic (PV) Cable Management Systems (CMS) provider Affordable Wire Management (AWM) calls for a reexamination of traditional notions about suspending cables behind modules.
The white paper, Impact of Rear-Hanging String-Cable-Bundle Shading on Performance Parameters of Bifacial Photovoltaic Modules, was co-authored by Dr. GovindaSamy Tamizhmani (Dr. Mani), an accomplished research professor and the director of the Photovoltaic Reliability Laboratory at ASU. It challenges the idea that positioning cables behind modules with hangers will cause harmful rear-side shading.
“Collaborating with the AWM team showcases how advanced applied research can help facilitate a new way of industry thinking and practices,” assessed Dr. Mani, author of more than 270 research publications and the driving force behind ASU’s Alternative Energy Technologies (now Clean Energy Systems) program.
Overview and Findings
The study found that rear-side cable bundles, ranging from groups of 2 to 16 cables and suspended from 3” and 6” hangers, have a negligible effect on PV module performance, contributing ≤0.6% to Pmax compared to the significantly larger 3–30% losses associated with mounting structures. Key electrical parameters (Pmax, Voc, Isc, and fill factor) remain unchanged within experimental uncertainty.
These results are consistent across 1-axis trackers and fixed-tilt systems, and across varying surface conditions, including white ground, indicating that the evaluated cable hanger designs are unlikely to cause meaningful performance loss in real-world applications. Industry experience and vendor assessments suggest that behind-the-module cable hanger systems can deliver notable efficiency gains, including reducing total cable length by approximately 20–30% and installation time by 15–20%, while eliminating pinch points near torque tubes and tracker components.
Shading can be detrimental, ultimately resulting in reduced energy yield, improper electrical output, and hot spots. The industry has been overly cautious about this and has consistently routed cables along structural components, such as torque tubes, to prevent rear shading. However, this practice has increased cable lengths and reduced reliability due to wiring interacting with moving system components. The research and white paper conclusively proved that shading is not a concern and that performance and reliability are not compromised by rear-hanging cables. These critical findings demonstrate that effective cable routing and design should be prioritized more heavily.
A New Metric and Future Applications
Normalized Shading Ratio (NSR), a novel metric, was developed and subsequently utilized to obtain results. Up to now, there has been no single method to quantify rear-side shading impacts in bifacial PV installations. Unlike traditional metrics, NSR isolates the performance effects of cable bundles from other factors, enabling a precise assessment of real-world power plant energy yield.
By establishing a standardized method for measuring a previously difficult-to-calculate variable, NSR not only strengthens the study’s conclusions but also provides the industry with a powerful new approach. In the future, NSR may help to inform design decisions and optimize power plant cable management layouts.
“This new metric, coupled with detailed analysis, proved that a rear-hanging cable strategy is critical for reducing excess cable length and minimizing the risk of cable snags,” said Dr. Mani. “Additionally, we disproved the fallacy that cable placement causes energy yield loss or hot-spots due to shade-induced electrical mismatch.”
Building on the findings of this new research, AWM is further refining its designs to support straight-line cable routing across module frames. AWM’s “Bonsai Golden Row” methodology for string-wire management, for example, provides installers with precise, repeatable guidance on routing cable along tracker systems. The Golden Row concept plays a critical role in utility-scale solar installations by establishing a standardized ‘reference row’ at the outset of construction. It serves as a blueprint for cable routing, attachment points, and overall system layout, enabling crews to replicate best practices efficiently across the entire site. By resolving potential conflicts early and creating a clear installation benchmark, Golden Row reduces rework, accelerates crew training, and drives greater uniformity and quality across large-scale projects.
AWM collaborators on the white paper included co-founder and CEO Scott Rand, co-founder and CTO Dan Smith, chief product officer Peter Hruby, VP of engineering Paul Subzak, and Benjamin de Fresart, director of product development.
“Partnering with Dr. Mani and the team at Arizona State University on this research has been a true honor,” said Dan Smith, co-founder and chief technology officer at AWM. “ASU is my alma mater, as well as Ben’s and Peter’s, which makes this collaboration meaningful on a personal level. Together, we have delivered findings that we believe will fundamentally change cable management design for bifacial PV across the utility-scale industry.”
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