To respond to the challenges brought about by explosive market demand and falling solar-panel prices, California-based SunPower turned to automation and smart manufacturing. The opportunity for change came with the opening of a new factory in Ensanada, Mexico, where the manufacturing system combining smart equipment, improved processes, plant automation and MES software delivered on traceability and compliance requirements as well as efficiencies, resulting in doubled capacity and overall cost/watt reduction of 6%.
SunPower had already seen the benefits of using MES software to meet its traceability and compliance requirements. As it was planning for a new assembly plant in Mexico, management decided it was now time to leverage the new opportunities offered by the combination of advanced plant automation and MES software.
SunPower created a cross-functional team and embarked on redesigning its manufacturing system to take full advantage of automation, with a view to deliver ROI within 18 months. MES software would play a central part in making plant operations smarter.
The general objective was for the future factory to produce about 3,000 high-quality modules, i.e. 1 megawatts per day, at full capacity. How would the company ensure it would achieve this however? From the onset, it quantified targets in terms of throughput, capacity per line, reduction in direct labor and cost / watt. The design of the solution would need to deliver on these goals.
Choosing the processes that would be automated was a crucial step. SunPower classified processes based on their cost and quality impact. Prioritized were those involving the highest level of manual labor, or involving decision-making, and thereby risk of error, as well as the processes most prone to defects.
Choosing a partner to deliver the MES software application
The MES software application would be the brain of the smart-manufacturing operations, necessary to integrate seamlessly with the PLCs, various devices throughout the lines and Oracle ERP. It would need to offer scalability at minimum investment so that new lines could be added at low cost, and be easy to learn and master.
“The MES system needed to fit into the overall design, be able to support quick fire implementation, be within budget and easy to learn. We chose Shopfoor-Online from Lighthouse Systems, which we already used in other plants, as it met these requirements well,” said Nikhil Padhi, manufacturing project manager in charge of key initiatives across the plants.
To achieve the degree of automation desired, the MES had to be embedded deep in process, enabled through a constant dialogue between the MES and the machines via automated scanners and sensors fitted on equipment.
The solution is built on a four-tier architecture: PLC, OPC, MES, ERP. The MES integrates seamlessly with the machines via an OPC server from Kepware and captures the machine transactions automatically with as little manual intervention as possible. The Oracle ERP consolidates all the manufacturing data for costing, reporting etc. Padhi worked closely with Lighthouse Systems to design this architecture.
The goal: Seamless data management
Master data like SKUs & Bills of Materials (BOM) are maintained in the PLM tool. The ERP holds the work orders (WOs) and inventory data. For completion of orders, the master data is downloaded to Shopfloor-Online: SKUs, BOM, inventory and work orders (WOs). Separate WOs are released for finished goods (modules) and works in process (string and laminates) to have better control over material consumption and traceability.
Shopfloor-Online generates serial numbers for each panel. As the module progresses through the assembly line, the MES identifies it automatically via its serial number and records transactions for each process step completed at the station. All incoming inventory (cells, solder paste, etc.) that is bought and consumed is labelled and traced in the MES to ensure full traceability.
Once the module reaches the end of the line, it is palletized and the pallets are sent to the truck. As the pallets are completed, information is sent back to Oracle for inventory reconciliation, cost/watt calculation and generation of financial statements. Pallets are shipped out of the Oracle warehouse-management system using handheld devices.
Supporting the manufacturing system
The factory runs 24/7, 365 days a year and with such a high level of integration between the different layers of the system, the MES software is a critical application. Lighthouse Systems is therefore providing 24/7 support to the SunPower team.
Some steps still require human operators, of course. Loading raw materials onto machines. Viisual inspections at the last stage. Responding to critical faults and rework. But some transactions, especially tests, are fully automated.
With smart manufacturing, improved processes and smart equipment, SunPower can reduce direct labor by 40% from the manual operations. It can reduce throughput time by 40%.
“Automation is often associated with job losses. But at Ensanada, thanks to a robust training program, there was practically no job loss as workers were re-deployed to new lines,” said Nihkil.
Reduced risks of warranty claims
The mandatory pass/fail test, as well as the classification test to measure actual power, no longer require human intervention. As a module is tested for power classification, in what is called a flash test, the MES knows which power output should be measured based on the solar cells used in its assembly. If the test returns a different power output, the MES automatically reclassifies the module based on its actual power and usage (commercial or residential). Possible human errors have been removed from this critical stage.
All the performance data for each panel is stored in the MES. That data is sent to Oracle for publication to the SunPower portal, where it is available to distributors and installers. The system gives full traceability of modules and raw material based on the module serial number. In case of a defect in a module, SunPower can track the fault through its production process and all the way back to suppliers.
This degree of traceability offered by the MES gives SunPower Ensanada confidence that it is compliant with U.S. import duty rules at all times.
Increased agility for new production introduction
With Shopfloor-Online MES seamlessly integrating with the PLM tool and Oracle E-business suite, SunPower has become more agile in launching new products. The MES manages to the smallest details of how products are made. It downloads BOMs from Oracle and as each panel is assembled, ensuring that every component is qualified, including the solder paste and screws. Shopfloor-Online makes it easy to configure a new product for production, and changeovers are quicker.
The future is bright.