Spire Corporation recently began an effort under the Department of Energy’s Photovoltaic Manufacturing Technology (PVMaT) project to develop automation for photovoltaic module assembly and testing processes after solar cell encapsulation. Module manufacturers were surveyed to identify current industry practices to help define the requirements for automated systems. Four main areas are being addressed: 1) module buffer storage between steps; 2) module edge trimming, sealing, and framing; 3) junction box installation; and 4) testing for module electrical performance, high voltage isolation, and ground continuity.

The objective of this work is to reduce the cost and improve the quality of terrestrial photovoltaic (PV) modules by developing automated high-throughput (5 MW/yr) processes for interconnecting crystalline silicon solar cells. A new automated processing system was developed for high-throughput, high-yield solar cell interconnection. The results of extensive processing evaluations with a range of different commercially produced cells are reported. Process yields typically exceeded 98%. No degradation in cell performance was observed. Modules made from cell strings fabricated with the new assembly system were subjected to accelerated environmental testing per IEC 1215 and IEEE 1262 standards. Testing consisted of thermal cycling, thermal and humidity-freeze cycling, and damp heat soaking. All modules passed these qualification tests, with an average power loss of only 2.3%.

This is the Final Technical Report for a program entitled ''Automated Solar Cell Assembly Teamed Process Research,'' funded by the US Department of Energy. This program was part of Phase 3A of the Photovoltaic Manufacturing Technology (PVMaT) project, which addressed the generic needs of the photovoltaic (PV) industry for improved quality, accelerated production scale-up, and substantially reduced manufacturing cost. Crystalline silicon solar cells (Czochralski monocrystalline, cast polycrystalline, and ribbon polycrystalline) are used in the great majority of PV modules produced in the US, accounting for 95% of all shipments in 1994. Spire's goal in this program was to reduce the cost of these modules by developing high throughput (5 MW per year) automated processes for interconnecting solar cells made from standard and thin silicon wafers. Spire achieved this goal by developing a completely new automated processing system, designated the SPI-ASSEMBLER{trademark} 5000, which is now offered as a commercial product to the PV industry. A discussion of the project and of the Assembler is provided.

This report describes work done under the Photovoltaic Manufacturing Technology (PVMaT) project, Phase 3A, which addresses problems that are generic to the photovoltaic (PV) industry. Spire`s objective during Phase 3A was to use its light soldering technology and experience to design and fabricate solar cell tabbing and interconnecting equipment to develop new, high-yield, high-throughput, fully automated processes for tabbing and interconnecting thin cells. Areas that were addressed include processing rates, process control, yield, throughput, material utilization efficiency, and increased use of automation. Spire teamed with Solec International, a PV module manufacturer, and the University of Massachusetts at Lowell`s Center for Productivity Enhancement (CPE), automation specialists, who are lower-tier subcontractors. A number of other PV manufacturers, including Siemens Solar, Mobil Solar, Solar Web, and Texas instruments, agreed to evaluate the processes developed under this program.

The objective of this work is to reduce the cost and improve the quality of terrestrial photovoltaic modules by developing automated high-throughput (5 MW/yr) processes for interconnecting thin silicon solar cells. New low-stress, high-throughput processes have been developed for cell loading, alignment, and inspection, interconnect ribbon handling, flux application, ribbon-to-cell soldering, cell string handling, and I-V testing of assembled cell strings. Both standard thickness (350 μm) and thin (200 μm) cells have been used to evaluate and refine these processes

This report describes work done under Phase 3A of the PVMaT project to address problems that are generic to the photovoltaics (PV) industry. Crystalline silicon solar cells were used in the majority of all terrestrial power modules shipped in 1992. Spire`s analysis in Phase 1 of the PVMaT project indicated that the use of thin ({le}200-{mu}m) silicon cells can substantially reduce module manufacturing costs, provided that processing yields remain as high as they are now for processing standard thickness cells. Because present solar cell tabbing and interconnecting processes have unacceptably high yield losses with such thin cells, the objective of this Phase 3A subcontract is to use Spire`s light soldering technology and experience in designing and fabricating solar cell tabbing and interconnecting equipment to develop high yield throughput, fully automated processes for tabbing and interconnecting thin cells.

Advanced automation processes are being development to reduce the cost and improve the quality of photovoltaic modules. Targeted processes are (1) solar cell assembly, in which the cells are electrically interconnected, (2) module lamination, which encapsulates the interconnected cells for protection from the weather, and (3) module testing, in which a current‐voltage curve is measured under simulated sunlight to quantify module performance. The current status and future plans for this development work are presented.

Automation of photovoltaic production is a necessary element to reduce the cost of PV modules. An important component of the production process is the encapsulation of the cells into an environmentally stable laminate. This process is presently labor intensive, and can be a bottleneck in production. The authors address the issues of automation in loading and unloading the laminate. An economic analysis is presented to justify the automation expense, by considering both reductions in labor and increases in throughput, especially when the process utilizes new “fast-cure” encapsulation materials