Solar Cell Manufacturing and Robot Automation: Right Fit, Right Robot

The United States has set 2015 as a goal to reach grid parity (that point where solar electricity is equal to grid electricity). No matter your thoughts on regulatory involvement, it is clear there will be a resurgence in investment, development, and innovation within the PV manufacturing community throughout the world, and it will largely be driven by technology. Finding the most effective tools and processes to gain more productivity and decrease costs within a set capital plan is paramount.

altWhile the significance of robot automation in the manufacturing of solar cells is obvious, which robot types and kinematics fit each unique process may not be as obvious. Which solar manufacturing areas offer the greatest return opportunities for robotic automation? Which robot type is best for a given solar application task and how does vision fit in? This article should act as a primer targeting these issues, and discusses how the solar industry can best maximize factory throughput, drive down costs, and improve efficiencies with robotic automation.

Automation’s Impact

Robots in the photovoltaic manufacturing process are important due to their ability to significantly reduce costs while continuing to increase their attractiveness compared to manual labor. Richard Swanson, CTO of SunPower Corporation, a leading manufacturer of solar technology, framed automation’s impact by discussing the economies of PV manufacturing in terms of labor. He explained that to produce one gigawatt of solar power, it requires 250 to 500 laborers to produce poly silicone, 250 to 500 laborers to process ingots, 3,000 to 6,000 people to manufacture the cells, 1,500 to 3,000 for the panel lamination and associated applications, and 2,500 to 5,000 for the solar system integration. In total, that’s 8,000 to 16,000 laborers required to produce 1 gigawatt of photovoltaic capacity. Therefore, to produce 500 gigawatts of solar power per year, that equates to roughly 4 million people. With more automation, inclusive of appropriately applied robotics, the solar industry can cut that labor to 1 million people, realizing a 75% savings in direct labor costs alone. Given this magnitude, it is critical that robots receive ample consideration in line design.

Selecting the Right Kinematic Solution

altA handful of considerations will provide good direction in selecting the correct robot. First and foremost, what is the payload requirement for the robot? Frequently, people only consider the products that are being handled. However, it is important to also consider the tooling solution or end-of-arm tool (EOAT).

Evaluating the motion requirements is also critical — not only the simple motion of picking and placing, but also what interferences exist among the robot, its linkages, and other items that may be in dynamic motion within the cell.

Consideration must also be given to how parts are produced and throughput requirements. How repeatable does the robot need to be? It’s also important here to recognize that robot manufacturers tend to speak in terms of repeatability, while engineers and designers tend to look at it from the standpoint of accuracy. A robot’s repeatability outlines the machine’s ability, once taught, to return to that taught position. Accuracy references the ability to input a given location digitally and have the robot move to that point in space “accurately.” This encompasses offsets and other digitally inputted motion parameters, and often varies within a given mechanical unit’s work envelope. A good understanding of a process’s requirements in combination with the capabilities of a given robotic solution requires careful evaluation.

Do your processes require special environmental considerations? Do you require a robot designed to eliminate the generation of particulates that might degrade the product? Or, does the robot need to be protected from process specific elements like slurry ingot processing?

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