PV modules - Main interface
The PV module parameter and properties, as well as their behavior, are defined through a 6-sheet dialog:
| Tab | Description |
|---|---|
| Basic Data, | Model type definition and main STC parameters, + summary of all the parameters involved in the model, + Tool showing the main results of the model, for any Irradiance and temperature conditions. |
| Additional data | Additional optional data specified for this module, and tools for the elaboration of the model. Low-light efficiency - Measured I/V curve - Sandia model parameters - IAM specifications - secondary parameters. |
| Model parameters | specifies some additional parameters necessary to the PV "one-diode" model, and calculates the model unknowns. |
| Size and Technology | Module and cells sizes, by-pass diodes, secondary characteristics, other specifications |
| Commercial data | Manufacturer, availability, prices |
| Graphs | a tool to visualize usual and less usual graphs of the PV-model behavior over a great variety of operating conditions. |
Synthesis of parameters associated with any module in PVsyst Database :
Basic data
| Nom Power | rated power specified by the manufacturer at STC. Should be close to Imp * Vmp. |
| Tolerance | +/- tolerances specified for the Nominal power. Only used in PVsyst for establishing the default value of the "Module quality loss" factor (fixed at Low tol + a quarter of the difference (High-Low)). |
| Technology | Gives choice for the main technologies of PV modules available on the market. Acts on the model. |
| GRef | Reference irradiance for the (Isc, Voc, Impp, Vmpp) specifications. Usually STC = 1000 W/m². |
| TRef | Reference temperature for the (Isc, Voc, Impp, Vmpp) specifications. Usually STC = 25°C, |
| Isc | Short circuit current at (GRef, TRef) conditions, |
| Voc | Open circuit voltage at (GRef, TRef) conditions, |
| Impp | Max. power point current at (GRef, TRef) conditions, |
| Vmpp | Max. power point voltage at (GRef, TRef) conditions, |
| muIsc | Temperature coefficient on Isc [mA/K] or [%/K] |
Additional data > Secondary parameters
| LID loss | Sometimes specified by the manufacturer Specified muVoc Normally muVoc is a result of the model. An alternative value may be specified here according to the datasheets. This value may eventually be used during the sizing (choice in the project's parameter definitions) |
| Absorptivity | Light absorptivity for the temperature evaluation through the thermal balance. Please let at default value. |
| Nb of bypass diodes | Useful for the electrical shading calculations in the Module Layout part. Normally 3 diodes for 60 and 72 cells, 4 diodes for 96 cells in series. |
| BRev | Special parameter for reverse voltage behavior; negligible influence in the shading calculations. Please let at default value. |
Model parameters
| Parameters of the "standard" one-diode model | |
| Rshunt | Shunt resistance at GRef. Measured as the inverse of the slope of the I/V characteristics around Isc at STC. If not specified, you can keep the value proposed by PVsyst. |
| Rsh (G=0) | Intercept at G=0 of the exponential behaviour of Rsh according to irradiance, |
| RshExp | Parameter of the exponential. Without very reliable determination, let it at its default value of 5.5. |
| Rseries, model | Series resistance involved in the one-diode model. For crystalline modules, you can keep the proposed value, which may be determined either according to a pre-defined gamma value, or low-light performances. |
| Rserie max | Maximum possible value of Rserie. A higher value would not allow the I/V characteristics to pass through the 3 reference points. |
| Rserie app | Apparent series resistance, as measured on the I/V curve as the inverse of the slope around Vco at (GRef, TRef). This slope is the sum of the Rserie (model) and the exponential effects. |
| Gamma | Diode Quality Factor, involved in the "one-diode" model. |
| muGamma | Thermal (linear) correction factor on Gamma, modification of the "standard" model for obtaining a specified muPmpp if necessary. |
| IoRef | Diode saturation current, involved in the "one-diode" model. |
| muVoc | Thermal behaviour of the Voc. Related to Rserie, but the manufacturer data is usually not attainable with reasonable other parameters. This value is a result of the model, and will usually not be compatible with the manufacturer's data. |
| muVocSpec | Specified manufacturer's data, may eventually be used during the sizing if the PVsyst model is not suited. |
| muPmpp | Normally a result of the model. May be forced to a specified value by acting on the muGamma parameter. |
| muPmppReq | Specified value for muPmpp if required. |
| Parameters for the modifications of the one-diode model for amorphous and CdTe technologies | |
| d²mutau | Specific parameter for the contribution of the recombination loss parameter. The validity domain of this value for finding a solution to the non-linear equations is strongly correlated with Rshunt and Rserie. It has implications on the thermal behaviour, especially of Vco. To our experience with the long-term measurements of several amorphous modules, the value of d²mutau parameter should be rather near to its maximum possible (about 80 to 90%). |
| Spectral corr | Parametrized correction according to Air mass and Kt. Fixed correlation (from University of Loughborough), may be activated or not. Not suited for CdTe technology. |
Sizes and technology
| NCell serie | Number of cells in series, necessary for the determination of the model, for one cell. |
| NCells parall | Number of cells in parallel, not really used by the model. |
| Cell Area | Area of one cell, will give sensitive area of the module, and allow the definition of a "cell" efficiency; Not necessary. |
| Module Length | Total length of the module. Necessary for the calculation of the module efficiency, |
| Module Width | Total width of the module. Necessary for the calculation of the module efficiency, |
| Apparent length | Tile modules or BIPV: if defined, will be used for the efficiency instead of total length, |
| Apparent width | Tile modules or BIPV: if defined, will be used for the efficiency instead of total width, |
| Max voltage IEC | Max. voltage allowed for the array in worst conditions Voc(low temp) - i.e. insulation voltage acc. to IEC standard (usually 1000 V), |
| Max voltage UL | Max. voltage allowed for the array in worst conditions Voc(low temp) - i.e. insulation voltage acc. to US standards (usually 600 V), |