Germany's Fraunhofer boosts solar efficiency

Germany's Fraunhofer Institute for Solar Energy Systems said this week it increased efficiency in multi-crystalline solar cells using what it calls a Metal Wrap Through process.

The process partially shifts the front side contacts over to the rear side, reducing the front side metallization almost in half.

Scientists at the institute said the first MWT cells from a prototype production line obtained more than 16 percent efficiency. That's an increase of up to a half percent over comparable standard silkscreen printed solar cells made up of the same multi-crystalline material, according to Fraunhofer.

The institute said the rear side contact of the MWT solar cells demands a small modification of the standard process.

"The additional expense is most definitely worth it because the minimization of metallization on the front side enables us to obtain reduced shading and thus increased energy production, which leads to a significant increase in efficiency," said Ralf Preu, head of PV Production Technology and Quality Assurance at Fraunhofer.

Harry Wirth, head of the institute's Photovoltaics Modules Group, said "Because we no longer have a problem with front side shading, it is now possible to use wider cell connectors. As a consequence, we obtain substantially lower losses during energy conduction."

The institute, founded in 1981, is the largest solar energy research center in Europe.

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