Ingrid G. Romijn

Input Parameters for the Simulation of Silicon Solar Cells in 2014

Within the silicon photovoltaics (PV) community, there are many approaches, tools, and input parameters for simulating solar cells, making it difficult for newcomers to establish a complete and representative starting point and imposing high requirements on experts to tediously state all assumptions and inputs for replication. In this review, we address these problems by providing complete and representative input parameter sets to simulate six major types of crystalline silicon solar cells. Where possible, the inputs are justified and up-to-date for the respective cell types, and they produce representative measurable cell characteristics. Details of the modeling approaches that can replicate the simulations are presented as well. The input parameters listed here provide a sensible and consistent reference point for researchers on which to base their refinements and extensions.

High Efficiency n-Type Metal-Wrap-Through Cells and Modules Using Industrial Processes

We report on our high efficiency n-type metal-wrap-through (MWT) cell and module technology. In this work, bifacial n-type MWT cells are produced by industrial processes in industrial full-scale and pilot-scale process equipment. N-type cells benefit from high recombination lifetime in the wafer and bifaciality. Also low-cost screen printed cells can yield over 20% efficiency. When combined with MWT technology, high-power back-contact modules result, which can employ very thin cells. We report a cell conversion efficiency of 20.5% (in-house measurement, certification pending), a significant gain compared to our earlier work. We will discuss performance of thin cells relative to thicker cells, comparing experimental results to modeling. Recently, two aspects of (mainly p-type) MWT technology have received increased attention: paste consumption and performance under reverse bias. We will discuss MWT paste consumption, showing how MWT technology, like multi-busbar technology, can support very low paste consumption. We also report on behavior of cells and modules under reverse bias. We also discuss the robustness of MWT technology to dissipation in hot spots under reverse bias. Finally, full-size modules have been made and cell-to-module ratios of the different I-V parameters were analysed. Modules from cells with average efficiency over 20% are pending. This work shows that low-cost n-type bifacial cells are suitable for industrial high efficiency back-contact technology.

Full wafer size IBC cell with polysilicon passivating contacts

We investigate the application of polysilicon carrier-selective passivating contacts to IBC cells. We optimized the passivation of n-type and p-type polysilicon layers by managing the hydrogen supply to the interfacial oxide. Both surface passivation and firing stability were addressed. The best results so far are obtained for passivation capping layers that contain Al2O3 and SiNx. For these passivated polysilicon layers, we present excellent J0 and implied Voc values on textured n-Cz wafers, with best values of < 1 fA/cm2 and 741 mV for n-type, and 10 fA/cm2 and 720 mV for p-type polysilicon, which are maintained after firing. The polysilicon layers were applied as carrier-selective passivating contacts for a full wafer size (156x156 mm2) IBC cell, using industrial compatible processes and commercially available n-type Cz wafers. The implied Voc on the cell reaches 725 mV, which enables IBC cell efficiencies of 24%. After metallization, Voc values of close to 700 mV were obtained.