Simulation of the natural characteristics of vertical $a$-Si : H/$\mu c$-Si:H tandem solar cells. 2. Analysis of the results and comparison with the experiment

Based on the general relations obtained in our previous studies, the photovoltaic characteristics of a model $a$-Si : H/$\mu c$-Si:H tandem solar cell (SC) are calculated and analyzed. The experimental and theoretical current-voltage (I–V) characteristics of the tandem SCs under AM1.5G(1000 W/m$^2$) illumination and in the dark are compared. It is demonstrated that the results of the theoretical calculation agree well with the experimental data. For a latitude of 45N, the annual hourly dependences of the ideality factor of the I–V characteristic, saturation current density of the diode component of the I–V characteristic, open-circuit voltage, short-circuit current, output power, efficiency, and I–V characteristic filling factor are constructed for a tandem SC. Comparison of the relative variations in these parameters during daylight hours at the equinox with previously calculated similar variations in the $a$-Si:H SC showed that they almost coincide, which confirms our earlier assumptions. Consequently, recommendations concerning the construction of solar power stations in certain regions, made by us previously on the basis of the calculated annual energy produced by the unit $a$-Si:H-SC area with regard to the statistical three-hour monthly NASA data on cloudiness, temperature, moisture, and other parameters, remain valid.