Suns-ILIT: Contact-less determination of local solar cell current-voltage characteristics

We present a novel method to analyze the local current-voltage I-V characteristics of both solar cells and cell precursors. The method, which we call “Suns-ILIT”, is based on illuminated lock-in thermography (ILIT) measurements and photoluminescence imaging (PLI) in open-circuit conditions with varying illumination intensities. Compared to conventional techniques for the determination of local solar cell parameters, the advantage of Suns-ILIT lies in the high accuracy while imposing minimal requirements on the sample. In particular, no electrical contact to the sample is needed. We derive the necessary equations from the contributions to the power dissipation and investigate the impact of the Peltier heating and cooling on the final outcome. The method is applied to a standard multicrystalline silicon PERC solar cell for demonstration. •We introduce a method to obtain spatially resolved information on the I-V characteristics of solar cells and precursors.•To this end, a combination of illuminated lock-in thermography and photoluminescence imaging is used.•The theory behind the method is explained in detail.•The method is demonstrated on a multicrystalline silicon PERC solar cell and compared to conventional methods.•The method does not need any electrical contacts and it allows for the I-V measurement of sub-cells in tandem devices.