Photovoltaic modules
General Information
The PVsystBasic database is limited to photovoltaic modules with a power output greater than approximately \(35\ \mathrm{Wp}\) for crystalline silicon modules, which are primarily suited for grid-connected systems.
PVsystBasic cannot guarantee the accuracy of the parameters contained in the database. These may contain transcription errors (including those from manufacturers) or result from subsequent changes to the technical data sheets. For this reason, the Data Source field generally indicates the year of the last update. When actually using a component, it is therefore strongly recommended to carefully verify all parameters using the most recent technical data sheets.
Please note
Older components are never removed from the database, as they may be used in older projects.
Liability
PVsyst SA assumes no liability for the integrity, accuracy, or performance of the data contained in the library.
Basic Data
Nominal Power
Nominal power specified by the manufacturer under STC conditions. It should be close to the product \(I_\mathsf{mp} \times V_\mathsf{mp}\).
Tolerance
Positive and negative tolerances specified for the nominal power. In PVsystBasic, these are used solely to determine the default value of the “Module Quality Loss” factor, set to the lower tolerance plus one-quarter of the difference between the upper and lower tolerances.
Technology
Allows you to select the primary photovoltaic module technology available on the market. This choice influences the calculation model used.
\(G_\mathsf{Ref}\)
Reference irradiance for the specifications \((I_\mathsf{sc}, V_\mathsf{oc}, I_\mathsf{mpp}, V_\mathsf{mpp})\). Generally corresponds to STC conditions, i.e., \(1\ 000\ \mathrm{W/m²}\).
\(T_\mathsf{Ref}\)
Reference temperature for the specifications \((I_\mathsf{sc}, V_\mathsf{oc}, I_\mathsf{mpp}, V_\mathsf{mpp})\). Generally corresponds to STC conditions, i.e., \(25\mathrm{°C}\).
\(I_\mathsf{sc}\)
Short-circuit current under conditions $(G_\mathsf{Ref}, \(T_\mathsf{Ref})\).
\(V_\mathsf{oc}\)
Open-circuit voltage under conditions \((G_\mathsf{Ref}, T_\mathsf{Ref})\).
\(I_\mathsf{mpp}\)
Current at the maximum power point under conditions \((G_\mathsf{Ref}, T_\mathsf{Ref})\).
\(V_\mathsf{mpp}\)
Voltage at the maximum power point under conditions \((G_\mathsf{Ref}, T_\mathsf{Ref})\).
\(μI_\mathsf{sc}\)
Temperature coefficient of the short-circuit current \(I_\mathsf{sc}\), expressed in \([\mathrm{mA/K}]\) or \([\mathrm{\%/K}]\).
Definitions of \(P_\mathsf{nom}\) and \(P_\mathsf{mpp}\) (STC)
The maximum power under STC conditions (or the nominal efficiency) may vary slightly depending on the following three competing definitions:
Nominal value (nameplate)
\(P_\mathsf{nom}\) corresponds to the nominal power (commercial designation) of the module. It serves as a reference for defining the nominal installed power of the system.
Product \(I_\mathsf{mpp} \times V_\mathsf{mpp}\)
The value \(I_\mathsf{mpp} \times V_\mathsf{mpp}\), as specified by the manufacturer under STC conditions, may differ from \(P_\mathsf{nom}\). This stems from ambiguities or changes in manufacturers’ specifications. Recently, some manufacturers have begun to incorporate positive rounding directly into their STC specifications. Thus, for a given module, they define values of \(V_\mathsf{mpp} \times I_\mathsf{mpp}\) that are \(2 \%\) to \(3 \%\) higher than the advertised nominal power.
In the PVsystBasic database, we now verify that the product \(I_\mathsf{mpp} \times V_\mathsf{mpp}\) matches \(P_\mathsf{nom}\) with a tolerance of \(0.2 \%\). If not, we adjust \(V_\mathsf{mpp}\), \(I_\mathsf{mpp}\), or both to restore the value \(P_\mathsf{nom}\). This may explain why PVsystBasic data does not always match manufacturers’ technical data sheets exactly.
Modeled Power \(P_\mathsf{mpp}\)
The power \(P_\mathsf{mpp}\) calculated from the single-diode model may be greater than the specified value \(I_\mathsf{mpp} \times V_\mathsf{mpp}\). This is because the model is constructed to make the I-V (or P-V) curve pass through the three characteristic points provided: \((0, I_\mathsf{sc})\), \((V_\mathsf{mp}, I_\mathsf{mp})\), and \((V_\mathsf{oc}, 0)\).
However, there is no guarantee that the specified point \((V_\mathsf{mp}, I_\mathsf{mp})\) corresponds exactly to the actual maximum of the modeled P-V curve. If the actual maximum is located elsewhere, the calculated power will naturally be higher.
Uncertainty Regarding Model Parameters
Certain parameters required by the model are generally neither specified in manufacturers’ technical data sheets nor defined by standard specifications. These include, in particular, the values of series resistance (\(R_\mathsf{serie}\)), shunt resistance (\(R_\mathsf{shunt}\)), and the exponential behavior of the shunt resistance.
PVsystBasic is therefore required to make assumptions to determine these parameters, based on its own experimental research on the model.
The value of \(R_\mathsf{serie}\) has a particularly significant influence on the module’s performance under low irradiance. The default value of \(R_\mathsf{serie}\) in PVsystBasic is based on an assumption related to the Gamma parameter.
However, some manufacturers sometimes provide particularly favorable values for \(R_\mathsf{serie}\), artificially improving the low-light response of their products. When integrating these modules into the database, PVsystBasic systematically verifies these parameters and does not accept values exceeding PVsystBasic standards, unless the manufacturer provides low-light performance measurements conducted by an independent certification institute.