## 2 Standards, PV Module and Inverter Requirements
### PV Module Requirements  
PV modules must meet a range of regulations and standards before they are considered suitable for sale and for renewable energy funding programs. PVs get their success due to long-term reliability and safety. On average, current PVs have a guarantee of use of around 25 years, with a degradation rate of 0.8%, based on international standards. An interesting study is presented in Reference [41] that analyzes the energy requirements for the production of PV and the generation throughout the useful life of the finished product. The research results showed that this technology is self-sustaining because it can generate several years of clean energy. In Reference [42], the standards for PV modules and components are summarized. In general, panels must comply with a range of international standards including IEC 61215, IEC 61646, IEC 61730-1/2, ISO 9000, ISO 14001. There are three types of main classifications for these PVs, which do an excellent job of identifying design, materials, and process flaws that could lead to premature field failures:  
* IEC 61215 for Crystalline Silicon Modules. * IEC 61646 for Thin Film Modules. * IEC 62108 for CPV Modules. From the electronic point of view, in Reference [43] it is specified that...The _PV_ cell, and module, is hypersensitive to ripple in the output current and voltage. The ripple does not damage the PV cell, but it reduces the available power dramatically... According to [44], the maximum voltage ripple allowed for a PV is defined as:  
\[\Delta v=\sqrt{\frac{2(K_{PV}-1)P_{MPP}}{3\alpha V_{MPP}+\beta}}=2\sqrt{\frac {2(K_{PV}-1)P_{MPP}}{\frac{d_{PV}^{2}}{dV_{PV}}^{2}}}, \tag{1}\]  
where \(\Delta v\) is the voltage ripple, \(P_{MPP}\) and \(V_{MPP}\) are the power and voltage at maximum power point (MPP), \(P_{PV}\) and \(V_{PV}\) are the power and nominal voltage of the panel, \(\alpha\) and \(\beta\) are the coefficients which describe the second-order Taylor approximation of the current and \(K_{PV}\) is the utilization ratio which is \begin{table}
\begin{tabular}{c c c} \hline \hline
**Issue** & **VDE 0126-1-1** & **VDE-AR-N 4105** \\ \hline \multirow{6}{*}{Leakage current} & RMS Value & \multirow{2}{*}{The use of the leakage current protection devices is inevitable. The standard IEC 60755 defines the detail requirements for the leakage current protection devices.} \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \hline \multirow{6}{*}{Grid frequency monitor} & \multirow{2}{*}{50.2 \(<\) f \(<\) 51.5} & Disconnected from the grid within 0.2s & Adjustable generation systems shall (for f decreases) the active power \(P_{M}\) generated instantaneously with a gradient of 40\% of \(P_{M}\) per Hertz. \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \hline \multirow{6}{*}{Active power} & \multirow{2}{*}{None} & The generation systems (\textgreater{}100 kW) could reduce their active power to set point provided by the network operator. \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \cline{2-3}  & & \\ \hline \multirow{6}{*}{Reactive power} & \multirow{2}{*}{None} & The generation systems should output required reactive power in accordance with the characteristic curve provided by the network operator. \\ \cline{2-3}  & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: German Code VDE Comparison [40]. given from the rate of average generated power to the theoretical MPP power. The coefficients are calculated as follows [43]:  
\[i_{PV}=\alpha{V_{PV}}^{2}+\beta{V_{PV}}+\gamma \tag{2}\]  
\[V_{PV}\approx V_{MPP}+\Delta v\ sin(wt) \tag{3}\]  
\[\alpha=\frac{1}{2}\frac{d^{2}I_{MPP}}{dV_{MPP}}^{2} \tag{4}\]  
\[\beta=\frac{dI_{MPP}}{dV_{MPP}}-2\alpha V_{MPP} \tag{5}\]  
\[\gamma=\alpha{V_{MPP}}^{2}-\frac{dI_{MPP}}{dV_{MPP}}V_{MPP}+I_{MPP}. \tag{6}\]  
For example, for FS55 CdTe PV module, 55 W, the parameters are calculated according to the Equations (1)-(6) as: \(\alpha=-0.0161\), \(\beta=1.0276\), and \(\gamma=-11.7038\).