Moser Baer Photo Voltaic: Reducing solar cell breakage from laser to shrink wrap

Moser Baer Photo Voltaic overcame the problem of damage to the delicate photovoltaic cells through the manufacturing process by devising an in-house solution to win the Qimpro quality award for manufacturing at the 22nd Qimpro Convetion

Moser Baer Photo Voltaic Limited (MBPV), a wholly-owned subsidiary of Moser Baer India Limited, is the first organisation to operate a fully automated mass production facility for solar-cells in India.

The plant has a capacity of 80 MW annually for Cell Line Plant. The company aims to propel MBPV to a leadership position in the global photo voltaic and solar power markets.

Cell breakage during Laser process to Shrink Wrap section was approximately between 5 per cent and 5.5 per cent based on three month data against the target maximum of 2.5 per cent for the stations. This was causing major line yield loss which was the greatest hurdle in achieving ABP target of line yield of 95 per cent.

The approach used to address the problem involved Six Sigma and DMAIC methodologies. The problem was identified at the tracking mechanism of Functional score card as this emerged as the biggest challenge to meet the business target. Initially, the breakage at Last section of Cell Line was close to 5 per cent which led to major line yield loss and was the biggest hurdle in achieving the Annual Business plan of the organisation.

Cells were breaking at final stage of classification, which resulted in loss of finished goods cost of $7.23 per cell. The monetary impact of the problem was estimated at Rs11.7 crore annually.

The cause of the high breakage of A & I type was analysed as centering plate hitting the cell corner at the time of closing, which was due to the cell tilting diagonally in the centering case after placement by robot, which in turn was caused by high centering opening gap providing additional space to cell for diagonal movement in case.

The solution to the problem involved changing the centering procedure of cases, which was suitably implemented. Additionally change was implemented in vacuum coupling of rotary table to eliminate cell breakage from Rotary indexing table.

The project yielded the following tangible and intangible benefits

• Business impact: Financial saving of over Rs11.7 crore annually
• Customer impact: Probability of customer complaint regarding cell breakage was reduced by 50 per cent.
• Horizontal deployment: Some of the solutions like robot setting/pad design have been replicated on other machines.
• Salient points: Completion of the project within time line has supported over all Cell Line yield to cross the world bench mark of over 95 per cent in fianancial year 2009-10.
• The design change of rotary coupling has been accepted and adopted by the original machine manufacturer for their future projects.

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