(a): U.S.C parameters (b) Solar cell made by four distributed homogeneous U.S.C: and (c) Final solar cell parameters. This final value depends greatly on the process and also on possible degradation during the solar cell's lifetime.įigure 4.
#HOW TO CALCULATE THE EFFICIENCY OF A SOLAR CELL IN PC1D SERIAL#
In the electrical model Figure 1, serial resistance rs is a lumped value that takes into account contact resistance on the emitter and the base, grid line con- tact and semiconductor resistivity. Now, to evaluate the impact of unit solar cells on the final device, we have chosen to see the influence of r s, r sh and J ph after a 50% variation of their initial value.Īpplication 2: Serial resistance discrepancy In a rapid approach we can evaluate the effects of local defects at the scale of individual USC on global performance, such as local shunt (r sh), local bad electrical contact (r s) and local bad photon collection or conversion (J ph) Generally, especially for multicrystalline ingots, heterogeneous properties govern final solar cell performances. To evaluate local properties it is useful to divide a large size into N unit solar cells, in Figure 3 in order to illustrate this method, we have chosen N = 4, the U.S.Cs are connected in parallel.įor this case each unit solar cells are identical ( Figure 4).Įvidently, the performances for the final solar cell are conserved, but this ideal case could be attributed to an homogeneous solar cell, in terms of materiel, for instance monocrystalline wafer and uniform processes. In a solar cell, global performances are largely relative to local ones, specifically in heterogeneous material such as multi-crystalline silicon. Solar Cell Modelized by N Unit Solar Cells (U.S.C) (r s = 1.5 Ω∙cm 2 and 0.15 Ω∙cm 2) (b) conversion efficiency evolution with concentration factor for two serial resistances values.ģ.3. (a) Short circuit current density evolution with concentration factor for two serial resistances values. Serial Resistance Loss in Concentrated Photo Voltaic CPV Solar CellsĬoncentrated photovoltaic is very attractive due to the fact that for the same solar cell size, the photovoltaic properties are increased with X, when the device is illuminated under X sun.įigure 2. Table 2 shows values obtained for three surface areas, it is clear that these results are in good agreement with the previous assumption.ģ.2. In order to verify this assumption, PC1D and SPICE codes are used, we have modelized a unit solar cell with parameters generally used in conventional p- type silicon solar cells. Thanks to this model, it is relatively easy to extrapolate photovoltaic parameters computed for a unit size solar cell to another size, just by calculating R s and R sh for the size S. Surface Area Effect on Photovoltaic Properties in One Sun Application To estimate J o, J ph, a, r s and r sh values, we have made some statistical measurements on elaborated solar cells characterized under standard one sun test condition (AM1, 5G) ( Table 1).ģ.1. To highlight this, for two solar cells with S and S' area respectively and if S' > S, Equations (4)-(6) imply that:īest values for parameters used in Equation (6)
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It is now obvious that for a given solar cell (material and process) the serial and shunt resistance decrease if the area increases. We can now introduce a normalized area solar cell (S = 1 cm 2 for instance) with resistance specifications given in Ω∙cm 2 units. This expression is simply derived from (1) with the assumption: If we want a quantitative comparison between solar cells with different surface areas (S), it is necessary to give the current density, J, versus voltage, V, equation. The difficulty in equation 1is that two kinds of parameters coexists, intensive parameter such as voltage (V), temperature (T),… and extensive ones such as current (I), resistances (R s and R sh ). One diode electrical model of illuminated solar cell.Įquation (1): (I-V) analytical expression for one exponential model solar cell