Robotically boxed

Automation dates back to the Industrial Revolution’s beginnings. The early 19th century saw a wave of social movement that protested heavily against the integration of automation into factories. An often cited example is the English textile machine operators’ protest against Jacquard’s automated weaving looms. Up to now, good, old human hands are not all that redundant yet, but an excursion through any sophisticated, state-of-the-art photovoltaic module production facility today means a meet and greet session with massive metal bodies that look a lot like relatives of Schwarzenegger’s Terminator. The truth is robots are faster and in terms of precision, programmable. In the market economy of competition, solar manufacturers have to ensure that their modules leave the factories fast enough to meet demand and good enough to meet or surpass quality requirements. Not to mention that variable costs might also be potentially lowered once a machine is placed to do the job, after taking into account payback periods. In this sense, the production technology market has been seeing a phenomenal growth in its offerings for manufacturers. The automation of the junction box (JB) assembly is one aspect of the production line where costs and time can be decreased and efficiency and quality increased. If JBs are not working properly due to faulty connections or any other issues that occur during the assembly step, then they can become the reason for module failure and probable fallouts. The surface mounting, contacting and isolation steps occur in a multi-step process. From the manual point of view, these processes in combination can be considered relatively slow, resulting in high failure probability and more workers for each step in order to ensure quality control and precision. Nevertheless, not every manufacturer sees the need to switch despite the smorgasbord of offerings in the robotic and JB worlds.

Staying hands-on

Perhaps before we start picturing 100 percent robot-run factories, one point should still be nevertheless noted. Not everything, everywhere can be robotized that easily – although cornucopians are allowed to hold a different standpoint. There are some aspects of the JB assembly that might still be preferably hand-operated. There are reasons to switch and reasons to stay hands-on.
pv magazine did a take on this theme, visiting the Conergy module manufacturing facility in Frankfurt Oder (see pv magazine 08/2009). As Conergy’s Public Relations Manager Katja Kargert pointed out then, for the supervision of the JB assembly station, only one operator is necessary to ensure that the materials are ready and to intervene in case of any mishaps or hiccups. For Conergy, the automation means that the boxes are precisely positioned after an automatic dispenser presses soldering paste onto the contacts, a robot applies double-sided adhesive tape onto the underside and attaches it to the module at 30-kilogram pressure and another robot seals the contacts. The tolerances are less than one millimeter. All these translate to high quality. According to Kargert, a much higher capacity of production is also enabled. Nevertheless, the last step of positioning the cover and sealing the contacts for insulation were done by hand. When probed at the time, Kargert stated that Conergy was seeking an intermediate, appropriate solution to automate these steps. Have there been any changes since then?
The answer: the sealing of the contacts comprise of a partly automated mixing and dispensing system and the cover remains positioned by human hands today at the facility. Conergy has an interesting reason to stay hands-on. Karget explains to pv magazine why it remains so. “The Conergy factory is highly automated. Still, sometimes, it makes sense to go manual on some production parts. On top of that, where manual labor makes sense, we then keep it that way. The manual aspects of the JB assembly are also associated with quality control (visual inspection) by a human being as well,” she adds.
The size of the factory is another aspect for the manufacturer in deciding whether robots need to be integrated for JB assembly. Yves Crepel, Solar Activity Manager at Staubli Robotics explains, “Our job is to sell the robotic equipment to the manufacturer. However, if the production is less than 25 megawatts, we suggest a semi automation of the production phase and not a robotic automation. This semi automation means that the worker has some tools to assemble and position the JB.” Crepel believes that robotic automation starts getting interesting only after 25 megawatts.
Molex’s Product Manager Peter Commane adds that the decision to automate also depends on the country or region where the production is located. Commane mentions that it is important to keep in mind that there are a number of grants and incentives to keep ‘green technology’ companies to produce locally. In particular, he pointed out North America, where there are funds available to ensure manufacturing flourishes. In North America, there is funding that focuses on production of equipment that improves the speed of manufacturing or installation, offered by the U.S. Department of Energy. 40 million U.S. dollars is said to be directed over three years for these manufacturing technologies.
Commane adds, “Manual production is still an option in China (although costs are rising), India and some new African based producers. But certainly, in Western based economies, every effort is being made to reduce labor content.” This asserts the location factor. During pv magazine’s tour of the HHV Solar Technology’s factory in Bangalore, India, it was noted that the JB assembly is done by hand. HVV’s Manager Arindam Sarker explains, “The basic machineries of the production line are from Spire. But when it comes to JB fixing, a conscious decision was made to go for manual operation.”
Factors to consider when moving into automatic assembly of JBs range from location to size. And there are of course, a myriad of other factors to consider. The integration of the automated system has to take into account components that are brought along by the JBs, for example, cables. That is why the cooperation between automation equipment manufacturers, JB developers and solar module producers is essential to simplify the complex incorporation.

Cost, quality and speed

Does automation of the JB assembly offer cost benefits for the module manufacturers? Manufacturers remain tight-lipped with the cost questions. Payback periods of one to two years were the numbers predicted by ABB Robotics, as long as the annual production stayed at 200MW (see pv magazine 08/2009). Adept Technology’s Rush LaSelle, Director of Global Sales and Marketing asserts, “The process and entity used to integrate the robot should be given as much consideration as the robot itself.” Meaning the entire design has to be accounted for as cost and not just the purchase of the robotic solution. Automation does not come cheap. Even though the equipment for the assembly portion is a one-off fixed cost as opposed to monthly wages, the initial amounts needing to be forked out are more than a couple of euros.
Molex’s Commane states, “Most European based PV companies need to compete in terms of costs. Once we reduce the manual side of the operation, panel assembly processes become more cost effective. PV panel producers cannot afford to have five to six people standing around and assembling the JB. With automation, producers can have one operator on the JB assembly station ensuring the process is completed according to standards.”
HVV Solar estimates that the average pay of the operator at the assembly station in Karnataka, India for example is approximately 350 U.S. dollars per month. Investing a one-off sum for automation and its knick-knacks would set the manufacturer back by thousands. Arindam sums it up, “Apart from the technical benefits, it is also obviously to gain economical benefits in this part of the world with manual set up, as all activities related to JB fixing is a plain table top operation with minimal capital expenditure, lowest utility requirement and relatively lower cost of human resource.”
Rush sees it somewhat otherwise. “Like all other processes, the production and assembly of the JB represents a cost to the overall manufacturing process. These costs are under constant pressure to be reduced including not only material costs, but also the labor to assemble them. By implementing automation to improve yield, decrease scrap, improve quality and reduce production costs, manufacturers move ever closer to achieving their cost projections,” he adds to the cost question.
From a quality question angle, one thing can be made clear. To err is human. Quality translates to efficiency. In the multiple steps at the JB station, errors can occur that can hamper the JB performance and therefore, the module performance. Schiller Automation states that photovoltaic module makers at times do not have the sensibility for the issues pertaining to the multi-processes of mounting, contacting and isolation. The company also asserts that the process can then be relatively slow, failure sensitive and often requires multiple line workers to reach a certain quality. Rush heralds the case for automation in terms of quality by saying that automation frequently improves the quality and tightens the specifications under which JBs can be produced which translate into a better build and greater efficiencies. Aesthetics wise, the positioning and attaching of the box can also be hampered by manual labor. Sarker sees it otherwise. “Manual operation gives us a few advantages technically to ensure better product quality. Every box gets inspected before fixation. It gives an assurance on the box quality and mainly on the bypass diodes. We have one more stage of inspection where experienced people check the connections and so on, and fix the top lid.” Fair enough.
Spelsberg’s Head of Photovoltaic Sales Martin Lütgens speaks of issues with manual handling. The fact that the controls are driven by robots from the first to the last step at this assembly station translates that human failures can be avoided as Lütgens points out. “Human failures can happen. Quality can then be compromised.” adds Lütgens.
Spire’s Vice President Ed Hurley adds, “Problems with uniform application of the sealant around the junction box are eliminated. Poor or inconsistent soldering of leads is also eliminated (with automation).” Commane concurs that manual mounting can have disadvantages. “Firstly, the number of persons involved. There would be training, transition and variation of skill levels, which could all contribute to the overall efficiency levels of the panel. As a result of using an automated process, the variability associated with the JB could be significantly reduced after completion of the flashing test.” LaSelle adds that automation provides consistence when compared to manual operations. He asserts that repeatable high quality is a necessity as well to drive costs down to achieve grid parity. Greater yield is delivered and a higher throughput per square foot of factory floor space according to the automation equipment maker. Can quality of the module be affected because of bad JB assembly? The answer is a loud yes.
Speed-wise, automation holds a clear advantage. The typical cycle time for Spire’s system is 60 seconds which include loading and unloading the module, bending the leads, dispensing the silicon, placement of the JB and soldering. Manual assembly varies greatly with skill levels but typically it can be pegged at 15 to 20 modules per hour, as Hurley says. Whether a line of operators can beat a fully automated solution is a no-brainer.

Robot offerings

Until recently, one aspect that slowed down the complete automation of the module manufacturing line was the JB section. According to Paul Merz, General Manager of Reis Robotics, the issues that hindered automation with the JB assembly step was the form factor of the JB and the threading of contacts (see pv magazine, 05/2010). Furthermore, the backsheet needs to be pried open, causing possible contamination of membranes. Solutions have started flooding the market. The market is now teeming with suppliers who can integrate their robotic equipment into the production line for the JB assembly portion with relative ease.
Taking a look at Spire’s Spi-J Boxer 2013 at work in the production line, it seems rather evident that the automation does everything to a perfect, precise point. The assembly system is designed to allow complete process flexibility according to Spire. The six-axis robot provides the precise adhesive path and box placement, removing the worry as to aesthetically misplaced boxes. There is active ribbon detection and the robot then welds the leads to the connection lugs in the JB for reliable connections. There is no operator in sight.
Reis Robotics delivered its solution for the connection of JBs for Renewable Energy Corporation’s module production facility in Singapore. Placement issues, joints, adhesive application problems and aesthetics were all taken into account in the product development. Reis Robotic’s J-Box Assembly is impressive in a sense that it offers the solutions for the problems mentioned by Merz. Steps that happen before lamination such as foil stamping and manual threading of contacts are avoided. In other words, the system does not require threading of cross connectors through the foils, eliminating the risk of membrane damage or contamination. Reis Robotics has installed its solution on lines of 20 megawatts, so their solution has no volume prerequisite.
Schiller Automation believes that if JBs do not reliably work, they can become the cause of severe quality problems that are then relevant for module failing and fall outs eventually. With the Schiller Automation, the surface mounting and contacting processing steps are in one process and is done on the fly. According to the company, the SunRiser JB250-300 concept includes the attaching and sealing of the JB to the rear side of the modules and establishing the required contacts. A module enters the SunRiser JB 250-300, a robot picks up the JB and activates the wetted surfaces. This activation before mounting assures that there is optimum initial tack. Sealant and/or adhesive is applied and a special gripper presses the JB against the module’s rear side to complete the contact formation. Electrical contacting is done via crimping technology.
LaSelle says that robots are flexible and can be integrated into the production line with relative ease. Robotic solutions are renowned for their versatility and the wide variety of applications into which they are deployed. Adept Technology itself offers robots that can be integrated into the solutions for JB automation, namely the Scara and the Cobra line that can be used for accurately placing adhesives or sealants before placing the lid on the enclosure. LaSelle adds, “However, it is important to note that a robot is one component of an automation solution. Attention must be paid to the manner in which to robot is deployed, the peripherals such as conveyors, tooling, safety systems, and other items critical to making the robot a productive part of a manufacturing process.”

Junction box side

Crepel says that most JBs are not defined to be easily automated. However, there are JB manufacturers who offer JBs that can be robotically mounted as well. Lütgens avers that junction box manufacturers do have an advantage when they offer products that can be integrated into automated lines in a module production facility. Lütgens affirms, “If you want professional products that are tested and certified by TÜV and UL for example and if you want to manufacture high volumes for global sales, then you definitely need automation.”
Collaboration with others in the industry is critical. One cannot swing by with a JB and expect the equipment makers to then adapt at the blink of an eye. Spelsberg, for example, works with industry players like Fraunhofer Institute. This then ensures that communication is enabled for innovation and ease in order for module manufacturers to run a smooth production line. Spelsberg employs a screwless contact technology that it considers as an advantage in its junction boxes. “The force of the clamps fixes the ribbons. The ribbons can be flexibly mounted by hand or by robots. An alternative method can also be welding, which we can also offer,” states Lütgens. Flexibility is an advantage that JB manufacturers can offer to have an upper hand as the company demonstrates.

Cooperation

Molex’s SolarSpec JB, for example, is another product offered for the fully automated line. Molex worked with module manufacturers for an all-round product. Meeting customer specifications and addressing the concerns with the complexities of automated JB assembly were some of the concerns Molex had to address. The SolarSpec JBs are soldered to the panel’s ribbons. To get the job done the best way possible, Molex also introduced its own Molex Solder Charge SMT technology that can be integrated to handle the soldering part. In a sense, it is an entire bundled package for module manufacturers. “Molex was a relatively late entry into the solar market and we did not want to merely duplicate products that were already available. Instead we focused on innovation and different ‘outside the box’ solutions that would give significant applied cost benefits to producers,” says Commane. According to him, the solder joints give less contact resistance compared to clamp joints and therefore, there would be no significant friction in the connection during its working life. This translates to a reduced risk of micro movements that can lead to arcing and other associated hazards as he asserts. Flexibility was also an aspect the company took into account. “Molex offers its SolarSpec in a packaging that is suitable for robotic pick and place equipment. We have a standard base unit and the diodes in the topside, which means that the top cover can be easily removed. This makes it more flexible when it comes to upgrading or replacing the box at a later time,” he adds.
Cooperation is removing the issue of standardization and limitations of JBs not fitting into automation solutions. JB manufacturers realize they have to offer flexible products for module makers who hold the option of going automatic or staying hands-on. And this all-important flexibility is being displayed by companies like Spelsberg and Molex. This does not, however, mean that JB manufacturers are compromising their own unique product designs.
Some JB companies are even offering their own add-on robotic solutions for the assembly process to facilitate incorporation. Module manufacturers can then shop for both, with the assurance that the solution will fit the JB with relative ease.
Conclusively, the module makers themselves have to decide if it makes sense to switch to automation in this comparatively small but crucial process step. Some, like HVV Solar in India, still see the sense (and cents) in traditional mounting methods. What is clear is that with the JB and automation offerings in the market, the cycle times are getting cut, with the promise of efficient production, quality and precision.