SCHOTT Solar Achieves Nearly 20% PV Efficiency Using New Fabrication Technology

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Innovations in the manufacture of high-efficiency solar cells continue to come fast and hard, holding out the promise that the cost of solar photovoltaic (PV) modules will continue moving lower down a declining cost curve. SCHOTT Solar AG on Dec. 12 announced a breakthrough: it manufactured a new type of industrial wafer size silicon solar PV cell with nearly 20% energy conversion efficiency that contains no silver – the most expensive raw material used in solar PV cell and module manufacturing.

It will no longer be necessary to use expensive silver in cell manufacturing if long-term stability can be demonstrated successfully, according to SCHOTT. Several innovative technologies were employed in achieving the latest results. In addition to using nickel-copper plating on the front side of the silicon solar PV cells. SCHOTT also employed ‘bleeding’, moving toward leading, edge PERC (Passivated Emitter and Rear Contact) technology to fabricate the cells. An alternative to screen printing of solar cells, PERC essentially increased the efficiency of solar cells by enabling it to capture reflected light from the cell’s backside.

“This new cell represents a real milestone on it’s way to achieving higher output at lower production costs,” explains Dr. Axel Metz, Director of Solar Cell Development at SCHOTT Solar. “We have been exploring every possible aspect of this technology over the last few years and have made important progress these last few months. Now, we were successful in combining these excellent results in a new cell. The next step will be to provide actual proof of its long-term stability,” he adds.

PERC, Back-coating Solar PV Cells

Part of ongoing efforts to move PERC from testing labs on to production lines, researchers at Germany’s Fraunhofer Institute for Solar Energy Systems in June last year published a paper detailing the results of solar cell manufacturing using PERC. They fabricated 192 standard 156 mm x 156 mm industrial solar PV cells with very efficiencies – above 20%. “The overall high efficiencies show that the PV-TEC (Photovoltaic Technology Evaluation Center) allows fabricating PERC cells with industrially related throughput with high reliability,” they concluded.

Fraunhofer PV-TEC researchers are now using PERC to fabricate “back-contact” silicon solar cells with efficiencies as high as 20.2%.

“We are very pleased to present these excellent results upon the fifth anniversary of PV-TEC. The results demonstrate, that silicon photovoltaics is still in the steep part of the learning curve,” project leader Dr. Daniel Biro stated in a news release.

Bosch Solar Energy has scaled up the PERC process. In April, the company announced large-scale production of PERC solar cells achieved record-breaking performances of 19.6% during testing at the Fraunhofer Institute. A record peak power output of 4.73 watts (W) was achieved by monocrystalline silicon PERC cells.