RESEARCHERS at the Institute for Solar Energy Research Hamelin (ISFH) have increased the conversion efficiency of industrial p-type silicon solar cells to a record 21.2%.
The new efficiency level is up from the typical 17.5% to 19.5% efficiency, and is the highest reported so far from industry typical silicon solar cells that use screen-printed metal contacts.
The researchers used new front-size metallisation pastes supplied by the Photovoltaics Business Unit of Heraeus Precious Metals to achieve the results, which have been confirmed by Fraunhofer ISE CalLab.
As opposed to conventional solar cells, passivated emitter rear cells (PERC) have a passivated rear-side, which increases the amount of energy captured from the cell.
ISFH's cell design incorporates a narrow front-side grid design using a dual printing process and an advanced five busbar design. This special layout enables the reduction of finger line widths to 46 micrometre, which decreases shadowing losses and serial resistance.
The narrower finger lines were printed with the Heraeus front-side silver metallisation paste, which was engineered for a high fill factor and low series resistance.
The busbars were printed using Heraeus' low activity paste. This paste does not fire through the passivation layer, which results in an additional boost in Voc.