Critical Components: Trends in solar cables and connectors

The uptake of solar power in India has been gaining traction with rapid ad­vancement in technologies and sustained interest from the public and private sectors. According to the Central Electri­city Authority, solar power accounts for an installed capacity of 67,078 MW as of April 2023, making it the top renewable en­ergy source in the country. Solar photovoltaic (PV) systems generate solar power by not relying solely on solar panels, but also on other vital technical components, which enable smooth power generation. As the number of projects being installed across the country grows, so does the demand for high quality equipment to fa­cilitate this expansion.

In the solar power generation ecosystem, cables and connectors comprise an im­portant supporting network. Because of their high number of electrical connectio­ns, these systems are prone to energy lo­sses at contact points. Although these co­mponents represent a minor portion of the total capital cost, changing them on a regular basis can add up to a significant cost overrun throughout the life of a solar plant. As a result, proper cable and connector selection and sizing is critical for cost reduction and system reliability.

Solar cables are specialised cables, whi­ch are used to link solar panels to other components in the solar power system. They are critical in transferring direct current (DC) electricity generated by solar pa­nels to inverters or charge controllers for conversion to alternating current (AC). In contrast, solar connectors facilitate ele­c­trical connectivity in solar energy systems and are used to connect solar panels with DC cables that carry DC power from the panels to the inverter.

Renewable Watch looks at different technology trends in the market of solar ca­b­les and connectors in India…

Solar cables

Solar cables are designed as a medium to carry solar power throughout a solar system and serve as connecting cables for critical equipment. They have a great mechanical strength that allows them to survive harsh weather conditions. These cables are typically installed outside and exposed to high temperatures in a solar project over their lifetime. The number of wires and their gauge are used to classify solar cables. Undersized cables can be a potential source of fire. The use of appropriate cable size prevents overheating and limits energy loss. When determining the wire size, it is important to consider the solar panel’s generation capacity as well as the distance between panels and the load. Cable sizes will rise as generation capacity and distance from load to panel increase.

Many developments are taking place in order to improve their efficiency. For ins­tance, in January 2023, Avient Corpo­ra­tion launched a technology of cross-linkable formulations for solar cables in solar energy applications. The company introduced a novel polymer material for PV ca­bles. The new solution’s structure has be­en desi­g­ned such that it results in inc­reased chemical resistance, mechanical performance and cable service temperature.

There are usually three types of solar cables deployed in a PV system:

  • DC solar cable: DC solar cables are single-core copper cables with insulation and sheath. They also come with ap­pro­priate connectors and are pre-built into panels and cannot be ch­anged later. They are module or string cables that are used within solar panels. In some cases, a string DC solar cable will be required to connect it to other panels.
  • Solar DC main cable: Main solar DC cables are made for larger power collecting cables with sizes varying typically 2 mm, 4 mm and 6 mm. They link the ge­­nerator junction box’s positive and negative cables to the central inverter. Mo­reover, they can either be single- or two-core cables. Two-core DC cables are ideal for connecting the solar power in­­verter to the generator connection box. Usually, main solar DC cables are us­ed for outdoor installations.
  • AC connection cable: The AC cable co­nnects the solar power inverter to the protective equipment and the power grid. A five-core AC cable is used to co­nnect smaller PV systems with three-ph­ase inverters to the grid.

Solar connectors

Solar panel connectors used to be predominantly composed of metal, making them bulky and difficult to install. Such connectors were also prone to corrosion and other weather-related problems, which could result in poor solar panel performance and efficiency. However, recent developments have seen the adoption of more modern materials in the fabrication of solar panel connections, such as plastic and rubber. These materials are more robust, weather resistant and easier to in­stall than metal counterparts. The solar po­wer industry uses several types of connectors or standard non-connector junction boxes. They are designed for easy and quick installation.

They typically employ a plug-and-play me­chanism, allowing for convenient and secure connections between solar cables, solar panels, inverters, charge controllers and other system components. Connec­tors could be pre-installed on solar panels or installed on-site. End-panels must then be linked to an inverter or a combiner box, which is frequently done on the job. Con­nections are created between solar panels and the microinverter in microinverter projects. These connections are typically pre-installed with wiring, particularly with plug-and-play integrated solar modules.

According to Waaree Energies Limited, the following are different types of solar connectors available in the market.

  • Amphenol connectors: These connectors are utilised in utility-scale solar systems. They are built to withstand large cu­­­rrents and voltages and are comm­only utilised in arrays of more than 1,000 modules.
  • H4 connectors: These connectors are deployed in big commercial and industrial solar systems. They are intended to handle greater currents and voltages and are commonly utilised in arrays of more than 100 modules.
  • MC4 connectors: These are the connectors most often used across resid­ential solar systems. They are waterproof, long-lasting and are intended for use with PV modules.
  • MC3 connectors: These connectors are identical to MC4 connectors but are intended for use with smaller PV modu­les. They are commonly seen in roof­top solar systems.
  • PV connectors: These connectors are generally used in home solar systems and are designed for use with PV modules. In terms of design and functioning, they are similar to MC4 connections.
  • TUV connectors: These connectors, which are identical to MC4 connectors in design and operation, are also extensively used in household solar systems.

In November 2022, Saudi Arabia-based Sabic, a company in the chemical industry, launched a polycarbonate (PC)-based copolymer resin, which is well suited for PV connector bodies and meets stricter performance and regulatory requirements for emerging 1.5 kV solar systems. The new LNP EXL9334P copolymer resin ac­hi­e­ves the highest comparative tracking in­dex. It also has excellent dimensional stability, strong heat resistance, durability, we­ather resistance and flame retardance at low temperatures.

In December 2022, Switzerland-based Staubli Electrical Connectors announced the introduction of a new solar connector in 2023 to improve upon its original MC4 cable coupler, addressing the rising need for cable components that can handle the larger size, greater power output and hi­gher line current. The coupler is rated for 1,500 volts and 95 amps DC and can accommodate bare or tinned copper conductors of 6 AWG, besides low-strand-count conductors.

Outlook

The future of solar cables and connectors appears to be bright. As the demand for solar energy grows, there will be a greater need for efficient and dependable cable and connector solutions to link solar panels, inverters and other solar power system components. It is critical to continue exploring for greater efficiency solar ca­bles and connections to limit power losses during transmission in order to improve the power generated. It is possible to achieve this through improving insulating materials and optimising contact resistance in connectors.

Additionally, designs with smart and integrated features such as built-in monitoring capabilities, enabling real-time performa­nce monitoring, defect detection and ma­intenance scheduling are preferred. In­te­gration with power management systems and energy storage technologies is also expected to grow in popularity.

Going forward, continuous improvement plans are aimed at boosting efficiency, du­rability, adaptability and safety, while lowering costs. These advancements will help sustain the expansion of solar energy as a clean and sustainable energy source.

By Nikita Choubey