Photovoltaic panel

Description of the Photovoltaic Panel component in Schematic Editor (t-tn002 - PV module-modeling and application)

Photovoltaic panel model

The photovoltaic panel element is modeled as a voltage-controlled current source I_PV with module capacitance C_PV connected in parallel, as shown in Figure 1. The current source I_PV is controlled by the voltage V_PV across the PV panel, in combination with a predefined PV model I-V curve.

Figure 1. Schematic diagram of a PV panel model.

The voltage-controlled current source I_PV represents a nonlinear resistor with the I-V characteristics equivalent to the standard PV cell characteristics, often modeled with the equivalent circuit given in Figure 2. The standard PV cell equivalent circuit model comprises an ideal semiconductor p-n junction, a current source that models irradiance flux, and series and shunt resistance that capture internal series and shunt losses.

Figure 2. Model of a PV cell

The PV cell IV curve is given as [1]:

I = I p h - I D = I p h - I 0 ( exp e ( V + I R s ) m k T c - 1 )

where m is an ideality factor (usually in the range of 1 to 2, with m =1 being ideal), k is the Boltzmann constant, e is the electron charge, and Tc is the junction temperature. The PV module is modeled as a compound parameterized PV cell, comprising an array of individual PV cells connected in series and/or parallel. Hence, a full module, or even a series of modules, is represented with a single PV panel element in the Typhoon Schematic Editor.

Photovoltaic panel component in Typhoon HIL Schematic Editor

Table 1. Photovoltaic panel component in the Schematic Editor
component component dialog window component parameters

Photovoltaic panel

Property tabs:

Generating I-V curves in the Typhoon HIL Waveform Generator

The Waveform Generator can be used to create I-V curves based on the following types of models:
  • Detailed
  • EN50530 Compatible
  • Normalized IV
The below parameters are necesarry to create the IV curve based on the detailed model:
  • Voc - open circuit voltage (*STC)
  • Isc - short circuit current (*STC)
  • ∆Isc/∆T - temperature coefficient of Isc (standard product parameter)
  • Number of cells (standard product parameter)
  • ∆V/VI at Voc - slope of the U/I characteristic at Voc operating point (product U/I curve)
  • p-n junction voltage gap (1.12 for Xtal; 1.75 for amorphous Si)
  • Ideality factor - a measure of how closely the diode follow the ideal diode equation (m in the range of 1 to 2)
*STC - standard test conditions

The preview curve will be displayed for the entered irradiance and temperature.

Figure 3. I-V and PV curves based on the detailed model
The below parameters are necessary to create the IV curve based on the EN50530 model:
  • Voc - open circuit voltage (*STC)
  • Isc - short circuit current (*STC)
  • Type - type of the PV panel (cSi, thin film, or user defined)
*STC - standard test conditions
Figure 4. I-V and PV curves based on the EN50530 model

Example: JKM220P-60

This section gives an example of reading the parameters needed for the Waveform Generator tool from a PV module datasheet given in Figure 5.

Figure 5. Excerpt from a Jinko-solar JKM220P-60 PV module datasheet

The next steps describe how to determine the ideality factor for a given PV panel. It cannot be read directly from the datasheet, rather it has to be determined experimentally. After entering all the available parameters from the datasheet to the Waveform Generator, an initial value for the ideality factor should be chosen. A good initial guess for crystalline silicon is around 2, while for amorphous silicon is less than 2. Finally, the maximum power displayed on the graph in the Waveform Generator should be compared to the maximum power provided in the datasheet. This process should be repeated until a close enough match between the maximum powers from the PV curve preview and the datasheet is obtained. PV curves for several ideality factors are shown in Figure 6.

Figure 6. Maximum power of the displayed PV curve for different ideality factors

Tab: General

  • Cpv
    • PV diode capacitance. [F]
  • Initial voltage
    • Initial voltage of the component. [V]

Tab: Signal Processing

  • Use signal processing PV model
    • If checked, models the PV panel using a signal processing EN50530 compatible PV model.
  • MPP measurement
    • Enables/disables monitoring of maximum power point (MPP). This property is available if the Use signal processing PV model checkbox is marked.
  • Execution rate
    • Type in the desired signal processing execution rate. This value must be compatible with other signal processing components of the same circuit: the value must be a multiple of the fastest execution rate in the circuit. There can be up to four different execution rates, but they must all be multiple of the basic simulation timestep. To specify the execution rate, you can use either decimal (e.g. 0.001) or exponential values (e.g. 1e-3) in seconds. Alternatively, you can type in ‘inherit’ in which case the component will be assigned execution rate based on the execution rate of the components it is receiving input from.

    • This property is available if the Use signal processing PV model checkbox is marked.

Measurements and inputs internal to the PV component

Available internal measurements are given in Table 2.

Table 2. Photovoltaic Panel analog outputs
Analog output variable name Description
C1 Voltage across the PV panel. [V]

The optional maximum power point (MPP) measurements, illumination and temperature measurements of the signal processing based PV model are available through probes inside the component. These outputs are given in Table 3.

Table 3. Photovoltaic Panel optional analog outputs
Analog output variable name Description
Imp Current at the maximum power point. [A]
Vmp Voltage at the maximum power point. [V]
MPP Power at the maximum power point. [W]
illuminationActual Illumination of the PV Panel, which equals the calculated value in case the illumination reference is delayed using ramping and/or scheduling. [W/m2]
temperatureActual Temperature of the PV Panel, which equals the calculated value in case the temperature reference is delayed using ramping and/or scheduling. [°C]

The references for the signal processing based EN50530 Compatible PV model are provided through SCADA inputs located inside the component. An overview of the available inputs is given in Table 4.

Table 4. Photovoltaic Panel inputs
Input Description
illumination An analog input that sets the illumination reference. [W/m2]
temperature An analog input that sets the temperature reference. [°C]
iscSTC An analog input that sets the short circuit current at standard operating conditions. [A]
vocSTC An analog input that sets the open circuit voltage at standard operating conditions. [V]
FFu An analog input that sets the FFu maximum power point to the open circuit voltage (technology dependent) ratio.
FFi An analog input that sets the FFi maximum power point to the short circuit current (technology dependent) ratio.
Cg An analog input that sets the Cg (technology dependent) correction factor. [W/m2]
Cv An analog input that sets the Cv (technology dependent) correction factor.
Cr An analog input that sets the Cr (technology dependent) correction factor. [m2/W]
Vl2h An analog input that sets the Vl2h voltage low to high (technology dependent) ratio.
alpha An analog input that sets the α (technology dependent) current temperature coefficient. [%/°C]
beta An analog input that sets the β (technology dependent) voltage temperature coefficient. [%/°C]
negCurrent A digital input that enables negative current if the input value is high.
illuminationInitial An analog input that sets the value of the illumination, which is used as an initial value in case of illumination ramping and/or scheduling at the start of the simulation. [W/m2]
temperatureInitial An analog input that sets the value of the temperature, which is used as an initial value in case of temperature ramping and/or scheduling at the start of the simulation. [°C]
rampTime An analog input that sets the duration of the ramping period. Ramping is applied to illumination and/or temperature references. [s]
executeAt An analog input that sets the value of the simulation time at which illumination and/or temperature references are applied. Scheduling of multiple simulation times before the first scheduled time has been reached is not supported. [s]
rampType A digital input that determines the shape of the transition of illumination and/or temperature references. If the input value is low, linear transition is applied. If the input value is high, exponential transition is applied.