# DC Cabling of Large-Scale Photovoltaic Power Plants
## 5 Testing of the Model/Case Study  
To test the DC cabling model, a hypothetical power plant with a nominal power of \(3\,\mathrm{MW}\) is considered. The PV plant is conceived as \(N_{\mathrm{A}}\) arrays, where each array contains \(N_{\mathrm{S}}\times N_{\mathrm{M}}\) solar panels connected in a serial-parallel configuration. The total array power is matched to the power of the selected inverter by choosing the \(N_{\mathrm{S}}\times N_{\mathrm{M}}\) configuration so that \(N_{\mathrm{S}}\times N_{\mathrm{M}}\times P_{\mathrm{P}}\leq P_{\mathrm{INV}}\), where \(P_{\mathrm{P}}\) is the nominal power of the selected panel and \(P_{\mathrm{INV}}\) is the nominal power of the selected inverter. All inverters are connected on the AC side to the input bus of the transformer, which connects the plant to the power system. The input data depend on the type of solar modules, and the model is made to support changes in all input data. The inputs to the model are the parameters given in Table 5. \begin{table}
\begin{tabular}{c c c c c c c} \hline \multicolumn{4}{c}{**Copper**} & \multicolumn{4}{c}{**Aluminum**} \\ \hline S & \(R_{I}\) & \(I_{\mathrm{N}}\) & \(I_{\mathrm{N}}\) & \(S\) & \(R_{I}\) & \(I_{\mathrm{N}}\) & \(I_{\mathrm{N}}\) \\
**[mm\({}^{2}\)]** & [\(\Omega\)/km] & **[A]** & **Mass** & **[km\({}^{2}\)]** & **[\(\Omega\)/km]** & **[A]** & **Mass** \\  & & & & & & \\
2.5 & 7.98 & 41 & 24 & \(-\) & \(-\) & \(-\) & \(-\) \\
4 & 4.95 & 55 & 38.4 & \(-\) & \(-\) & \(-\) & \(-\) \\
6 & 3.30 & 70 & 57.6 & \(-\) & \(-\) & \(-\) & \(-\) \\
10 & 1.91 & 98 & 96 & \(-\) & \(-\) & \(-\) & \(-\) \\
16 & 1.21 & 132 & 153.6 & \(-\) & \(-\) & \(-\) & \(-\) \\
25 & 0.78 & 176 & 240 & \(-\) & \(-\) & \(-\) & \(-\) \\
35 & 0.554 & 218 & 336 & 95 & 0.32 & 216 & 430 \\
50 & 0.386 & 276 & 480 & 120 & 0.253 & 253 & 510 \\
70 & 0.272 & 347 & 672 & 185 & 0.164 & 340 & 760 \\
95 & 0.206 & 416 & 912 & 240 & 0.125 & 408 & 960 \\
120 & 0.161 & 488 & 1152 & 300 & 0.1 & 473 & 1160 \\ \hline \end{tabular}
\end{table} 
Table 4: Parameters of standard cables (data from [27; 39]). The output results are presented in Table 6, where the solar module HCM78 \(\times\) 9-440 W [40] and a 16 kW power inverter are used. The output data can be used for techno-economic analysis, feasibility studies, design, etc. The power losses on the DC cables were specifically analyzed. Figure 8 shows the results of the simulation of losses on the DC cables as a function of the nominal power of the inverter. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{2}{c}{**Geometry of Array**} & \multicolumn{2}{c}{**Geometry of System**} \\ \hline Array width, \(b\) & 10.75 m & System width & 132.6 m \\ Array length, \(a\) & 14.73 m & System length & 225.8 m \\ Array surface, \(A\) & 158.42 m\({}^{2}\) & System surface & 29,942 m\({}^{2}\) \\ \hline \multicolumn{4}{c}{System component data} \\ \hline Number of inverters & 189 & Number of arrays & 189 \\ Number of solar modules & 6804 & Number of solar modules in the array & 36 \\ Number of connectors & 7938 & Number of solar modules in the string & 12 \\ Number of blocking diodes & 567 & Number of strings in the array & 3 \\ \hline Cables & Length & Cross-section & Mass \\ \hline Type 1 & 20,010.62 m & 4 mm\({}^{2}\) & 168.68 kg \\ Type 2 & 0 m & & \\ \hline Power losses on DC cabling & & 0.4239\% & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Output data of the model.