Series resistance characterization of industrial silicon solar cells with screen-printed contacts using hotmelt paste
This work presents the results of a detailed series resistance characterization of silicon solar cells with screen-printed front contacts using hotmelt silver paste. Applying the hotmelt technology energy conversion efficiencies up to 18.0% on monocrystalline wafers with a size of 12.5 cut X 12.5 cut have been achieved, an increase of 0.3% absolute compared to cells with conventional screen-printed contacts. This is mainly due to the reduction in the finger resistance to values as low as 14 Omega/m, which reduces the series resistance of the solar cell significantly. To retrieve the lumped series resistance as accurately as possible under the operating condition, different determination methods have been analyzed. Methods under consideration were fitting of the two-diode equation function to a dark IV-curve, integration of the area A under an IV-curve, comparison of a j(sc)-V-oc with a one-sun IV-curve, comparison of the jsc and V-oc points of a shaded curve with the one-sun IV-curve as well as comparison of a dark IV-curve with a one-sun IV-curve, and comparison of IV-curves measured at different light intensities. The performed investigations have shown that the latter four methods all resulted in reliable series resistance values.