The transition towards more sustainable materials and practices is gaining focus, in addition to the accelerating energy demand. Sustainable energy transition equates to more renewables, which demands durable, cost-effective, and a sustainable electrical distribution network.

Historically, copper has been the preferred material for busbars in low-voltage electrical distribution systems, due to its superior conductivity, durability, and widespread availability.

Copper plays a critical role in energy transition, particularly due to its essential function in battery technology. The criticality of copper is magnified by the rapid expansion of renewable energy storage systems and the global shift toward electric vehicles.

Copper's role extends beyond just the batteries; it is also a key component in the infrastructure of EV charging stations, inverters, and power distribution systems. The critical need for copper in energy storage and distribution highlights the importance of finding more sustainable and efficient ways to manage its use.

Quest for sustainable materials

Aluminium has emerged as a strong contender in this quest for sustainable materials. While aluminium has a lower conductivity than copper, its numerous advantages, including its abundance, lower cost, and significantly lighter weight, make it an attractive option for electrical infrastructure.

Moreover, as Saleem H Ali emphasises in Soil to Foil: Aluminium and the Quest for Industrial Sustainability, aluminium’s role in circular economies has made it an increasingly valuable resource in the push for industrial sustainability. Its recyclability, lower environmental footprint, and adaptability to evolving technological demands position aluminium as a key material for the future.

In this article, we explore the techno-economic potential of aluminium as a substitute for copper in low-voltage electrical distribution panels, with a focus on cost-efficiency, thermal performance, and environmental impact.

Through a comparative analysis of aluminium and copper busbars, we aim to assess aluminium’s capability to not only meet the demands of modern electrical systems but also drive the industry towards more sustainable and cost-effective practices.

By leveraging aluminium’s advantages, industries can reduce both costs and carbon footprints, while simultaneously supporting the global transition towards more resilient and sustainable energy infrastructures.

This study provides a result of a techno-economic analysis of Al busbar in low voltage electrical distribution panel. To achieve the research objectives, we conducted a rigorous thermal analysis through current injection experiments and a techno-economic evaluation encompassing various parameters such as weight, resistance, transportation logistics, and cost-efficiency. Furthermore, we designed the busbars that would facilitate a reduction in power loss.

Bolted busbar connections, commonly using copper, are prevalent in battery systems. This study explores the potential benefits of aluminium as a lighter, cost-effective alternative, specifically focusing on its reliability and resistance to corrosion.

Testing was conducted on four bolted aluminium configurations, considering both operational and environmental conditions relevant to battery systems. Nickel-plated aluminium demonstrated the most stable resistance, enduring more than 6,000 cycles across varied temperatures and remaining unaffected in corrosive conditions.

In contrast, brushed aluminium connections showed more resistance variation, emphasising the need for a joint performance factor below 1.5 for long-term reliability. As the battery industry grows more interested in aluminium, this research highlights the importance of developing standardised testing environments for aluminium contacts and offers a methodology for evaluating new contact configurations.

The prevalent use of copper in power systems presents challenges related to cost, weight, corrosion, and copper reserve depletion. These challenges align with findings in the literature that underscore copper’s limitations.

To address these issues, this research explores the substitution of copper with Al, known for its cost-effectiveness, lower weight, and corrosion resistance. By conducting thermal analysis (IEC Standard 61439-1-2020) and techno-economic analysis on 150kW load scenarios, we compared copper (30*5 mm DIN standard) and Al (40*10 mm DIN standard) busbars.

The research aims to recommend specific Al sizes that outperform copper, reducing costs, resistance, power loss, and weight in power distribution systems, contributing to the ongoing discourse on sustainable material choices.

Research method

Figure 1 depicts the copper bus bar assembly vs the Al bus bar assembly, both enclosed within boxes.

Notably, these bus bars share a common length of 800mm; however, the copper bus bar has a width and thickness of 30mm and 5mm, respectively, per DIN Standard 63671. Conversely, the Al bus bar maintains the same length but features a width of 40mm and a thickness of 10mm, aligning with DIN Standard 63670 specifications.

Experimental configuration and arrangement

A 300A-rated alternating current was applied to assess the temperature rise at the busbar’s incoming point. Subsequently, thermal behaviour was observed at various positions along the busbars.

The evaluation followed the guidelines specified in the IEC standard IEC-61439-1 (IEC, 2020) which facilitated the measurement of temperature rise for copper and Al bus bars. Thermocouples were strategically placed on the bus bars, and their positions are visually represented in Figure 2.

In the distribution panel, we deployed 17 thermocouples to measure temperatures at specific locations within the box precisely. These thermocouples were of the K-type variety, composed of nickel-chromium and nickel-aluminium elements, and had an average length of 2.5 metres. They were strategically positioned to connect observation points on the busbars to a temperature meter.

Our experiment focused on various key points within the busbar box, including the incoming busbar terminal, areas near joints, midpoints along the busbars, and the outgoing terminal of a 150-kW large busbar box. We affixed specialised sensors to these locations using Al tape. These sensors recorded temperature readings at hourly intervals.

Our primary objective was to ensure that the temperature did not exceed a predefined limit when subjected to a 300A current. The test continued until a one-degree celsius temperature increase per hour was observed at all measuring points.

We then compared these data points to the room temperature to determine the extent of temperature rise. Additionally, we paid close attention to how we securely attached the temperature sensors to the busbars.

Finally, we conducted a comparative analysis of the results for both copper and Al busbars. This comparison encompassed factors such as energy losses, cost considerations, and ensuring that the metal components did not experience excessive heating, ensuring the metal structures’ safety when use in electrical applications. K-type temperature sensors were intentionally located along the busbars to arrest temperature variations at definite points.

Load scenarios and data collection

Our thermal experiments encompassed a range of load scenarios, employing injected currents to emulate distinct operating conditions. Temperature data was gathered using K-type sensors that interfaced with a data logger device.

Over the course of approximately eight hours, the data logger recorded temperature readings at 30-minute intervals, ceasing its operation when the busbars reached a saturation point characterised by a one-degree celsius temperature rise, in compliance with the IEC 61439 standard.

Our focus during the experiment was determining temperature changes and designs in Al and copper busbars. Results from the logger machine’s recorded data illuminated the responses of these materials to varying current concentrations and load conditions. The temperature analysis table is given in the Table.1

Table 1 Position of Sensors on the busbar during testing (Temperature rise test of large busbar box 25/07/23)

A meticulous cost examination revealed a significant cost differential between Al and copper. Specifically, Al exhibited a cost advantage, approximately one-third of the expense associated with copper.

Weight considerations held paramount importance in our evaluation. It is noteworthy that Al possesses a lower weight profile than copper. This weight reduction facilitates ease of transportation and handling. A comprehensive weight comparison and corresponding data are provided in Table 2 within the results section.

The reduced weight of Al translated into heightened transportation efficiency, effectively mitigating the logistical complexities and associated costs that arise when dealing with bulkier copper components.

Our assessment of losses considered adherence to DIN standards, ensuring rigorous precision in our analysis. Notably, our observations indicated that Al busbars, when conforming to DIN standards, exhibited diminished losses when juxtaposed with copper counterparts. Furthermore, the augmentation of the Al busbar’s cross-sectional area notably improved its resistance characteristics.

To amalgamate our findings effectively, we directed our attention towards a detailed scenario involving a three-phase load with a power rating of 150KW. This targeted approach allowed us to meticulously discern the performance disparities between Al and copper under controlled conditions, culminating in developing distinct insights, with a pronounced emphasis on the economic aspects elucidated through cost analysis.

Results and discussion

Thermal testing: we conducted a comprehensive thermal analysis of Al and copper busbars, adhering to the rigorous standards in IEC guidelines.

During testing, Al and copper initially exhibited temperature increases at joint positions due to issues related to tightness and finishing. However, after addressing these specific challenges, the subsequent tests yielded successful results. Notably, these results supported the viability of replacing copper busbars of size 30*5 with Al counterparts sized at 40*10 within the context of a 150-kW large bus bar box. Figure 3 shows results from thermal analysis for both Al and Cu.

Figure 3: Thermal analysis of Al (T sensors) and Cu (U sensors) Busbar boxes

Over six hours, all sensors from groups T (T1 to T17) for Al and U (U1 to U17) for Cu demonstrated a general upward trend in temperature, suggesting a consistent rise over time, albeit with distinct patterns within and between groups.

In group T, sensors T1 and T2 have showcased a relatively steady increase, indicating a consistent heating environment, while T3, T4, and T5 exhibited pronounced fluctuations, with T4 starting at a notably higher temperature. Comparatively, U1 and U2 from group U portrayed a steeper rise initially, moderating over time, with U1 consistently registering higher temperatures.

Meanwhile, U3 to U5 showed more varied fluctuations, with U5 experiencing a significant dip and subsequent rise between the second and third hours, hinting at a dynamic thermal environment.

Across both groups, the initial temperatures were highest for T4 and U1, and by the end of the six-hour period, T1 and U1 registered the highest temperatures, suggesting the greatest overall heating effect.

The results derived from our thermal analysis distinctly affirmed Al’s compliance with the IEC 61439 – 2022 standards. This validation underscores Al’s capacity to replace copper in the 150-kW load scenario, offering a range of advantages such as reduced losses, lower weight, enhanced corrosion resistance, and cost-efficiency.

Notably, both copper and Al busbars exhibited comparable heat dissipation capabilities. Compliance with DIN standards necessitated an increase in width and depth for the Al bus bar, which subsequently passed the thermal testing regimen.

Cost analysis

The cost analysis shows that Al bus bars have lower material costs and reduced production expenses associated to copper. This price benefit makes Al a preferable choice for to use in the field, while maintaining condition and operation.

For weight comparison, aluminium’s weight is less than copper’s weight when carrying the same current. Weight is an essential factor to consider in the techno-economic analysis of aluminium compared to copper, as it can impact a system’s cost, efficiency, and performance. Here is a comparison of the weight of aluminium and copper. 

The inherent cost-effectiveness, lighter weight, and enhanced ease of transportation and installation associated with Al render it a favourable choice throughout the system’s entire lifecycle. Moreover, the significant size difference between Al and copper busbars further underscores the economic viability of adopting Al as a preferred material in this context.

Power losses comparison of aluminium and copper

In the context of power losses, we evaluated Al bus bar designs and their associated costs when compared to copper. We found that the 30*5 Al bus bar performed worse than Copper regarding losses and current-carrying capacity. However, a 40*5  Al bus bar outperformed copper for eight to 10 years, its losses increased.

Finally, a 40*10 Al bus bar proved better than copper for a 150-kW load over an extended period. All bus bars were designed according to DIN standards. Refer to Table 3 and Figure 4 for detailed data.

Figure 4: Power loss comparison of AL and CU bus bar

To demonstrate aluminium’s viability, a practical case study involving a 150-KW load and fibre-reinforced material was conducted. This study confirms aluminium’s ability to meet load and material requirements, reinforcing its suitability for the amalgamation of aluminium’s thermal performance, cost-effectiveness, and weight advantages positions it as an appealing choice for real-world applications.

Conclusions

The present study embarked on a meticulous journey to unravel the comparative merits and demerits of utilising Al and copper as materials for bus bars, leveraging a robust experimental model grounded in real-time data collection and analysis.

Through a series of thermal and techno-economic analyses, we have shed light on these materials' pivotal role in influencing the efficiency, cost-effectiveness, and sustainability of low-voltage bus bar systems.

Our findings underscore the potential of Al as a viable alternative to copper, demonstrating notable advantages in terms of reduced weight, lower costs, and favourable thermal performance characteristics.

The techno-economic analysis further substantiated the economic viability of Al, highlighting its capacity to diminish power delivery charges and thereby alleviate the financial burden on consumers.

Moreover, the research fills a significant gap in the existing literature by being one of the pioneering studies conducted in Pakistan, offering a fresh perspective in a region where such analyses are scant.

The adherence to DIN standards and IEC standard 61439-1-2020 in the design and thermal analysis phases ensured a rigorous approach to the research, paving the way for reliable and replicable results.

As we navigate a world grappling with the pressing demands of energy efficiency and sustainable development, the insights garnered from this study stand as a testament to the untapped potential of Al in revolutionising busbar systems.

It beckons a paradigm shift in the industry, urging stakeholders to reconsider the conventional preference for copper considering the compelling advantages presented by Al.

Looking forward, we advocate for further research to delve deeper into this promising avenue, exploring the full benefits of Al busbars. We aspire that this study serves as a springboard for future investigations, fostering innovations grounded in sustainability and economic prudence.

Acknowledgements: The authors are grateful to Electric Gears Corporations (Pt.) Ltd. Karachi Pakistan for providing the testing facility for thermal, cost, and power loss analysis.

References

1) Aluminium and the Quest for Industrial Sustainability Saleem Ali

2) https://doi.org/10.7312/jerv20598

3) https://cup.columbia.edu/book/soil-to-foil/9780231204484

Authors:  Faisal Najam (LinkedIn) is an electrical engineer, currently working as a sales manager at Elektrolead Private Limited, Karachi, Pakistan. Lala Rukh (LinkedIn) is a doctoral researcher in MaREI–Science Foundation Ireland Research Centre for Energy, Climate and Marine Research and Innovation at the University of Galway. She is an electrical engineer and has master's degrees in energy systems and marine plastics abatement. Nayyar Hussain (LinkedIn) is an associate professor at the Mehran University of Engineering and Technology Jamshoro Pakistan. Shoaib Ahmed Khatri (LinkedIn) is an assistant professor at the Mehran University of Engineering and Technology Jamshoro Pakistan.