The characteristics of the diode for a single module is defined by the equation:
|
Where:
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Id is the current of the diode (A), Vd is the voltage of the diode (V), I0 is the saturation current of the diode (A), nI is the ideality factor which is generally close to 1.0, k is the Boltzmann constant(1.3806 e-23 J / K) q is the electron charge (1.6022 e-19 C) T is the temperature of the cell (K) and Ncell is the number of cells connected in series in a module PV.
The figure below shows the characteristic I-V curves, and the dependence of the solar irradiance S and the module temperature T.
Feature I-V dependence on the Solar Irradiance and the Temperature
Mask and Parameters
The PV model has two tabs:
- Model: Configuration choices (array) and the 5 PV model parameters
- Database: Allows the user to select a module PV from over 21,000 modules from leading manufacturers from the California Energy Commission.
Model Tab
Parameter name | Description | Unit | Variable |
---|---|---|---|
Description | PV Module name selected in the tab Database. | Description | |
Number of modules connected in parallel | Number of modules connected in parallel. | # | Npar |
Number of modules connected in series | Number of modules connected in series. | # | Nser |
Maximum power Pmax | Power obtained at the point of maximum power (Vmp,Imp). P max = Vmp x Imp. | W | Pmax |
Number of cells per unit | Number of cells per module. | # | Ncell |
Open circuit voltage | Voltage obtained when the terminals of the assembly (array) are left open. | V | Voc |
Short circuit current | Current obtained when the terminals of the assembly (array) are shorted. | A | Isc |
Voltage at maximum power point | Voltage at maximum power point. | V | Vmp |
Current at maximum power point | Current at maximum power point. | A | Imp |
Temperature coefficient of Voc | Sets the change in Voc depending on the temperature. | % / ° C | Beta_Voc_pc |
Temperature coefficient of Isc | Sets the change in Isc depending on the temperature. | % / ° C | Alpha_Isc_pc |
Light-generated current | Current for a module under standard test conditions (STC) coming out of the controllable current source which models the current generated by the light. | A | IL_ref |
Diode saturation current | The diode saturation current for a module under standard test conditions (STC). | A | I0_ref |
Diode ideality factor | PV Module ideality factor. | # | nI_ref |
shunt resistance | shunt resistor for under standard test conditions module (STC). | Ohm | Rsh_ref |
Series resistance | series resistance for a module under standard test conditions (STC). | Ohm | Rs_ref |
Database Tab
This tab lets you choose a PV from the database of the CEC. The user can enter the module name or just a letter and then click on Inquiry and all the modules that contain that letter or name appear in the table. Once the selected module, the user must click Load parameters to load the model with the respective parameter values.
The user can also right click on the desired module and then choose the option “Load parameters in component” for the model parameters to be updated.
Ports, Inputs, Outputs and Signals Available for Monitoring
Ports
Name | Description |
---|---|
Plus | Network connector on the DC side; The + indicates this is the positive terminal (supports only 1-phase connections). |
Minus | Network connector on the DC side; The - indicates this is the negative terminal (supports only 1-phase connections). |
Inputs
Name | Description | Units |
---|---|---|
T | Temperature of the PV cell | Celsius |
S | Sun irradiance over the PV | W/m2 |
Outputs
Name | Description | Units |
---|---|---|
V | DC output voltage | V |
I | DC output current | A |
Sensors
Name | Description | Unit |
---|---|---|
S | Signal representing the irradiance to which the array is exposed | W/m2 |
T | Signal representing the temperature to which the array is exposed | Celsius |
V | DC output voltage measurement | V |
I | DC output current measurement | A |
Additional Information
PV Panel Equivalent Circuit Diagram
The terminology followed in the PV modeling is given below:
- Cell: single unit of the photovoltaic semiconductor that converts the solar irradiance into electricity.
- Module: group of cells connected in series and parallel to achieve a desired voltage and current.
PV Modeling
In the PV model developed, the diode is replaced by a non-linear resistor which can accurately model the PV at different temperatures as an input. Note that the temperature can be changed during the simulation in offline as well as in real time. On the other hand, the shunt resistor has been replaced by a variable resistor according to the irradiance S. The figure below shows the internal circuit of the PV model.
The model PV model contains many types of modules PV predefined from the database Photovoltaic (PV) modules to the Energy Commission's Solar Equipment Lists of the California Energy Commission (CEC) (November 2018). More than 21,000 modules from leading manufacturers are listed in this database includes the manufacturer's specifications measured for standard test conditions (STC) (Irradiance of 1000 W/m2 and 25 ° C).
Limitations
- When the user creates their own PV module, they must also update the 5 parameters from an optimization function external to HYPERSIM.
- At the time of this writing (DEC2019), this model does not participate in the load flow solution.
References
L. G. Monteiro Oliveira et al., "Computational implementation of photovoltaic modules mathematical models for software application to estimate PV systems energy production," 2015 International Conference on Solar Energy and Building (ICSoEB), Sousse, 2015, pp. 1-6
W. De Soto, S. A. Klein and W. Beckman. « Improvement and validation of a model for photovoltaic array performance ». Solar energy, vol. 80, no. 1, pp. 78-88, 2007
MathWorks, PV Array Mathworks.com. https://www.mathworks.com/help/physmod/sps/powersys/ref/pvarray.html
Photovoltaic (PV) Modules to the Energy Commission’s Solar Equipment Lists, California Energy Commission, Nov. 2018. [Online]. Available: https://www.gosolarcalifornia.ca.gov/equipment/pv_modules.php