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					</table>The rapid evolution of solar module technology is driving changes in photovoltaic (PV) junction box design, with manufacturers moving from conventional single-box configurations toward split-box designs and higher current ratings to accommodate high-wattage modules.
Industry experts say further technological development will depend significantly on the performance and availability of suitable bypass diodes. Material quality is also becoming increasingly important as manufacturers face pressure to reduce costs.
Junction boxes form part of a solar module&#8217;s electrical system, housing bypass diodes and connections that carry electricity from the module.
The Shift to Split-Box Designs
As module wattages and current levels increase, junction box designs and component specifications are evolving to accommodate changing electrical characteristics.
The market is currently seeing widespread adoption of three-piece split junction-box configurations, with 30A and 35A current ratings becoming common for high-power modules. Schottky SMD bypass diodes are widely used because their lower forward voltage helps reduce power dissipation and heat generation during forward-bias operation.
According to Shyam Talsaniya, Head of Technology at <a href="https://orinpv.com/" target="_blank" rel="noopener">Orin Group</a>, 1500V system voltage is currently widely used, while 2000V systems are also beginning to emerge. Junction boxes designed for 2000V applications require improved electrical insulation, higher creepage and clearance distances, and suitable materials to ensure adequate dielectric strength and long-term insulation reliability.
“Another emerging trend is the development of smart junction boxes, which can incorporate sensing and control electronics to monitor parameters such as module current, voltage, power, and temperature. Depending on the system architecture, these solutions can also provide power-control or shutdown functionality when required, enabling improved module-level monitoring, protection, and system safety,” Talsaniya added.
Overall, the technology is moving toward higher current and voltage capability, improved thermal and insulation performance, smarter monitoring and control, and more compact split-box designs.
Mahipalsingh Gohil, Co-founder and Executive Director at <a href="https://www.sparkhubrenewables.com/" target="_blank" rel="noopener">Sparkhub Renewables</a>, said junction boxes require updated diode specifications to keep pace with rising module wattages. Earlier, current ratings of around 20 A to 25 A were common.
Junction boxes traditionally used single-chip diodes, but manufacturers are increasingly moving toward double-chip diodes for higher current requirements.
The diode-to-cable connection process is also changing. Manufacturers that once relied primarily on crimping are increasingly combining crimping with soldering.
“This improves connection durability and supports better electrical performance. It is also being adopted to improve the junction box&#8217;s overall durability and reliability,” Gohil said.
Talsaniya noted that as module wattages increase, both voltage and current ratings tend to rise, with current becoming a greater challenge to accommodate. For higher-current junction boxes, such as 35A designs, better-performing SMD bypass diodes, including dual-trench configurations, are required to achieve lower forward voltage and minimize heat generation.
“Diode heat dissipation also needs optimization through appropriate thermal fins, copper plates, and heat-transfer paths. In parallel, junction-box plastics need higher RTI (Relative Thermal Index) and better weather/UV resistance to ensure that any heat generated during operation does not accelerate material degradation,” he added.
Aru Aditya Vasu, CEO at <a href="https://arbon.co.in/" target="_blank" rel="noopener">Arbon Cleantech</a>, said ratings have increased from around 30 A toward 35 A, with the possibility of even higher ratings in the future. Junction box technology is also evolving alongside module technologies such as TOPCon and back-contact designs. As module current and voltage requirements increase, junction box designs, internal components, and polymers must also evolve.
Gohil observed that most TOPCon modules currently being manufactured use split-box configurations, while manufacturers developing future module technologies are also largely experimenting with split designs.
“Conventional single junction box designs are gradually becoming outdated for newer module configurations,” he added.
Vasu commented that the transition is already well advanced, estimating that split junction boxes account for the majority of the Indian market. Conventional single-box designs are now largely restricted to smaller modules used in applications such as streetlights, and several manufacturers have stopped producing them altogether.
Split-diode junction boxes can be used with mono PERC, TOPCon, HJT, and other high-wattage modules, with product selection primarily determined by a module&#8217;s electrical specifications and design requirements.
Talsaniya added that in India, adoption of split-diode configurations became noticeable around 2020, and the shift has become clearer with growing module sizes and the adoption of half-cut cell configurations. “The key advantage is that the electrical and thermal load is distributed across multiple junction boxes, resulting in lower heat generation per junction box. In addition, the busbars connecting the junction boxes do not need to travel the longer distances associated with a single-box configuration. This can reduce looping losses and associated electrical resistance, improving the module&#8217;s overall electrical design.”
Quality Versus Cost
Junction boxes are high-volume, low-margin components, making automation increasingly important for manufacturers seeking to improve production efficiency while maintaining competitive pricing and consistent quality.
Domestic manufacturers also face significant price competition from Chinese suppliers. Industry participants caution that aggressive cost reduction can create reliability risks if manufacturers compromise on housing materials, connectors, or diodes, potentially leading to failures over a module&#8217;s operating life.
“Indian module manufacturers are increasingly open to domestically produced junction boxes. However, supplier qualification remains lengthy, as components must be included in the approved bill of materials and supported by the required documentation, testing, and certifications. The approval process can take nearly a year, limiting new manufacturers&#8217; ability to scale even when production infrastructure is available. Local manufacturing can improve quality inspection and compliance verification, but dependence on Chinese raw materials remains a major challenge,” noted one manufacturer.
Domestic Manufacturing Expands
India&#8217;s junction box market is expanding alongside domestic solar module manufacturing.
India now <a href="https://www.mercomindia.com/solar-module-capacity-under-almm-rises-to-228-gw" target="_blank" rel="noopener">has</a> around 225 GW of Approved List of Models and Manufacturers (ALMM)-compliant module capacity.
Gohil said junction box manufacturers are planning around 40 GW of additional capacity. As this comes online, domestic production could meet a significant share of module manufacturers&#8217; requirements, reducing dependence on imported junction boxes.
However, the expansion of module manufacturing capacity does not necessarily translate into equivalent near-term junction box demand because actual annual module production and solar installations remain significantly below announced manufacturing capacity.
Vasu noted that India&#8217;s domestic junction box manufacturing capacity is already estimated at more than 100 GW and is broadly sufficient to meet current requirements. Imports nevertheless continue to compete with locally manufactured products, while some domestic production facilities remain underutilized.
Localization Challenges
The expansion of India&#8217;s module manufacturing base is creating opportunities to localize junction boxes and other components such as encapsulants, backsheets, and frames.
Talsaniya observed that a major challenge is the availability of high-current bypass diodes. These are specialized semiconductor components that are not commonly used in other applications. India currently lacks sufficient manufacturing capacity and capability to produce these diodes at the scale, cost, and quality required for reliable, commercially viable junction boxes. As a result, current production remains heavily dependent on imported diodes.
“Another challenge is injection-molding capability for small and intricate junction-box components. The molding process requires precise tooling and process control, and the industry still relies heavily on overseas molds. When design changes, development work, or modifications are required, this dependence can lengthen timelines. Hence, strengthening domestic capabilities in precision mould manufacturing, mould maintenance, and specialized injection molding would be important for reducing development lead times and supporting the scale-up of India&#8217;s junction-box manufacturing ecosystem,” Talsaniya added.
Gohil said the tax and duty structure on finished junction boxes and the raw materials domestic manufacturers use can put local producers at a disadvantage. Certain raw materials imported from China, for example, can attract GST of around 18%, while a 1,500 V DC junction box is sold at around 5% GST. This can narrow the price difference between imported finished junction boxes and domestically manufactured products.
“Policy support that creates a more balanced duty structure for imported finished junction boxes could help domestic manufacturing expand,” Gohil said.
Compared with modules, cells, and glass, the junction box segment has relatively limited support through duties, standards, or manufacturing incentive programs.
Industry participants suggest that greater emphasis on value-based procurement and minimum domestic sourcing requirements could support local component manufacturing. They argue that such measures could strengthen quality control while reducing the solar manufacturing industry&#8217;s dependence on imported supply chains.

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