Design and analysis of a highly reliable large-area Z-type transparent module for dye-sensitized solar cells

The design methodologies for large-area transparent dye-sensitized solar cells (DSSCs) and modules for building-integrated photovoltaic (BIPV) windows are presented. Using electrochemical impedance spectroscopy and the optical/electrical measurements of a small-sized (∼9 × 5 mm) test cell, the basic circuitry of a DSSC is generated in a unit cell for building the 2-dimensional equivalent circuit model of a large-area Z-type transparent DSSC module (300 × 300 mm) on P-Spice. Based on solar irradiation at a window-side monitored for a year, we have proposed a DSSC module design that generates the maximal electrical energy for the best levelized cost of electricity. While simulations using the developed model estimated a module efficiency of ∼3.23% and an annual electrical energy generation of 448 kWh/m2, the fabricated module with a cell width of ∼18 mm exhibited an efficiency of ∼3.19%; the design is also conducive for practical manufacturing and thermal reliability. The developed model demonstrates the operational behaviors of DSSC modules under local shadowing conditions that match with the experiments. The feasibility of the DSSC as a reverse diode, working as a distributed by-pass diode eliminating the current mismatch loss is also demonstrated; this is beneficial for long-term operations. This work can be applied to other types of DSSCs and can be used for producing DSSC-based BIPV windows.