MANUFACTURINGAUTOMATION
electroluminescence (EL). EL is frequently applied at the end of the production process and mandatory in case of deviations of module power from the expected power (based on cell efficiency). EL is a key diagnostic tool and isualizes potential deficiencies of modules.
Cell production
The cell production is based on an inline scheme, 4 lines are operated in parallel. The wafers are supplied by an automated transport system, the production process proceeds in-line from texture to flasher. A 3 cluster concept allows the exchange of cells at 3 positions of the process, e.g. to use overhead buffers to ensure an optimum tool utilization in case of maintenance of tools.
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Fig.3 (above) shows the scheme of the module production, starting from the glass supply / glass washing and the cell supply to the flasher at the end of the production process.
Key elements are: automated transport of materials / modules with a tact rate of 115 sec (in some parts like junction box mounting: 21 sec). The task of the operators is focussed on production and quality control.
automatic processes for soldering (see Fig. 4), lamination, framing, mounting of junction box (see Fig.5) and flashing.
Fig 4: Layup / fully automated soldering
quality control based on inspections, e.g. camera systems, electrical testing (incl. assessment of the diode characteristics) and
In line measurements for key parameters like reflection, sheet resistance etc are under SPC control, the data are transferred to the production control system, which allows the correlation of data from all different production areas. Besides the standard electrical measurements EL is applied to generate a pareto of cell efficiency detractors.
The careful investigation of silicon material properties has been proven to be essential for cell efficiency optimization [1], as well as the optimization of screenprint.
Wafer production
The wafer production also uses automation, e.g. for brick grinding, glueing of bricks in preparation of the saw process. A prototype tool for transferring the wafers from the cleaning container to the final in-line cleaning of wafers is successfully integrated. Wafer measurements cover all critical parameters of wafer production. The wafer data can be used to correlate to data from cell and module. After taking all measurements the transport system carries the wafer to storage or directly to cell production.
Selective emitter
In 2010 Conergy will apply the selective emitter to its cell production, based on a cooperation with Manz AG. The selective emitter process is based on laseroverdoping [2,3]. Using the phosphorous glass (PSG) as doping source the laser provides additional thermal budget, to diffuse additional P- doping from the PSG into the silicon.
This technique allows the combination of a homogeneously doped emitter of 110-120 Ohm/sq with higher doping, e.g.<50 Ohm/sq, in the
www.solar-pv-management.com Issue II 2011
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