solar – solar panel

## Synopsis

module generators;
class solar {
enumeration {SUPPLY_DRIVEN=5, CONSTANT_PF=4, CONSTANT_PQ=2, CONSTANT_V=1, UNKNOWN=0} generator_mode;
enumeration {ONLINE=2, OFFLINE=1} generator_status;
enumeration {CONCENTRATOR=5, THIN_FILM_GA_AS=4, AMORPHOUS_SILICON=3, MULTI_CRYSTAL_SILICON=2, SINGLE_CRYSTAL_SILICON=1} panel_type;
enumeration {DC=1, AC=2} power_type;
enumeration {GROUND_MOUNTED=2, ROOF_MOUNTED=1} INSTALLATION_TYPE;
enumeration {DEFAULT=1, SOLPOS=2} SOLAR_TILT_MODEL; New in 2.3!
enumeration {DEFAULT=1, FLATPLATE=2} SOLAR_POWER_MODEL; New in 2.3!
double a_coeff; New in 2.3!
double b_coeff; New in 2.3!
double dT_coeff; New in 2.3!
double T_coeff[%/degC]; New in 2.3!
double NOCT[degF];
double Tmodule[degF];
double Tambient[degF];
double wind_speed[mph];
double ambient_temeprature[degF];
double Insolation[W/sf];
double Rinternal[Ohm];
double Rated_Insolation[W/sf];
double Pmax_temp_coeff;
double Voc_temp_coeff;
complex V_Max[V];
complex Voc_Max[V];
complex Voc[V];
double efficiency[unit];
double area[sf];
double soiling[pu]; New in 2.3!
double derating[pu]; New in 2.3!
double Rated_kVA[kVA];
complex P_Out[kW];
complex V_Out[V];
complex I_Out[A];
complex VA_Out[VA];
object weather;
double tilt_angle[deg]; New in 2.3!
double orientation_azimuth[deg]; New in 2.3!
bool latitude_angle_fix; New in 2.3!
enumeration {DEFAULT=0,FIXED_AXIS=1,ONE_AXIS=2,TWO_AXIS=3,AZIMUTH_AXIS=4}orientation; New in 2.3!
set {S=5, N=4, C=3, B=2, A=1} phases;
}


## Remarks

A solar panel (also known as solar module or photovoltaic module/panel) is an assembly of solar cells. Solar panels must be connected via a parent inverter.

## Properties

Property name Type Unit Description
generator_mode enumeration none (UNKNOWN,CONSTANT_V,CONSTANT_PQ,CONSTANT_PF,SUPPLY_DRIVEN) Currently solar must operate in SUPPLY_DRIVEN.
generator_status enumeration none (ONLINE, OFFLINE)
panel_type enumeration none Uses pre-defined panel technologies.(SINGLE_CRYSTAL_SILICON, MULTI_CRYSTAL_SILICON, AMORPHOUS_SILICON, THIN_FILM_GA_AS, CONCENTRATOR)
power_type enumeration none Defines whether the connection is AC or DC. Currently not used.
INSTALLATION_TYPE enumeration none (ROOF_MOUNTED, GROUND_MOUNTED) Currently not used.
SOLAR_TILT_MODEL enumeration none (DEFAULT, SOLPOS) Defines the tilt model to utilize for tilted array calculations.
SOLAR_POWER_MODEL enumeration none (DEFAULT, FLATPLATE,PV_CURVE) Defines if the PV array output efficiency should be adjusted for temperatures of the cells using a simple efficiency method, or the SAM simple flat plate efficiency model, or use the PV Curve (DC bus) model.
a_coeff double none a coefficient for temperature correction forumula New in 2.3!
b_coeff double none b coefficient for temperature correction forumula New in 2.3!
dT_coeff double %/degC Temperature difference coefficient for temperature correction forumula New in 2.3!
T_coeff double none Maximum power temperature coefficient for temperature correction forumula New in 2.3!
NOCT double degF Nominal operating cell temperature.
Tmodule double degF Calculated internal temperature of the PV module.
Tambient double degF Outside air temperature.
wind_speed double mph Outside wind speed. Currently not used.
ambient_temperature double degF Current ambient temperature of air
Insolation double W/sf Solar radiation incident upon the solar panel.
Rinternal double Ohm Currently not used.
Rated_Insolation double W/sf Insolation level that the cell is rated for.
Pmax_temp_coeff double Coefficient for the effects of temperature changes on the actual power output.
Voc_temp_coeff double Coefficient for the effects of temperature changes on the DC terminal voltage.
V_Max complex V Defines the maximum operating voltage of the PV module.
Voc_Max complex V Voc max of the solar module
Voc complex V Defines the open circuit voltage as specified by the PV manufacturer.
efficiency double unit Defines the efficiency of power conversion from the solar insolation to DC power.
area double sf Defines the surface area of the solar module.
soiling double pu Soiling of the array factor - representing dirt on the array.  New in 2.3!
derating double pu Panel derating to account for manufacturing variances.  New in 2.3!
Rated kVA double kVA Currently not used.
P_Out complex kW Currently not used.
V_Out complex V DC voltage passed to the inverter object
I_Out complex A DC current passed to the inverter object
VA_Out complex VA Actual power delivered to the inverter
weather object n/a Reference to a climate object from which temperature, humidity, and solar flux are collected
shading_factor double pu Shading factor for scaling solar power to the array  New in 2.3!
tilt_angle double deg Tilt angle of PV array  New in 2.3!
orientation_azimuth double deg Facing direction of the PV array  New in 2.3!
latitude_angle_fix bool n/a Fix tilt angle to installation latitude value (latitude comes from climate data) New in 2.3!
orientation enumeration n/a Type of panel orientation. Types DEFAULT and FIXED_AXIS are currently implemented  New in 2.3!
phases set n/a (A,B,C,N,S) Currently not used.
pvc_U_oc_V double V Open circuit voltage
pvc_I_sc_A double A Short circuit current
pvc_U_m_V double V Voltage at maximum power point
pvc_I_m_A double A Current at maximum power point

## Default

Default Parameter Values
Parameter Default value
NOTOC 118.4 degF
Tcell 69.8 degF
Tambient 77 degF
Insolation 0
Rinternal 0.05
Rated_Insolation 92.902
V_Max 79.34
Voc 91.22
Voc_Max 91.22
area 323 sf
soiling_factor 0.95
derating_factor 0.95
a_coeff -2.81
b_coeff -0.0455
dT_coeff 0.0
T_coeff -0.5 %/degC
efficiency 0.10
generator_mode SUPPLY_DRIVEN
generator_status ONLINE
panel_type SINGLE_CRYSTAL_SILICON
tilt_angle 45 deg
orientation_azimuth 0 (equator facing)
latitude_angle_fix FALSE
orientation DEFAULT
SOLAR_TILT_MODEL DEFAULT
SOLAR_POWER_MODEL DEFAULT

## Example

A minimal model could be created via:

object solar {
generator_mode SUPPLY_DRIVEN;
generator_status ONLINE;
panel_type SINGLE_CRYSTAL_SILICON;
efficiency 0.2;
parent inverter1;
area 2500;
}


## Model with DC Bus Model

The solar panel, when properly interfaced with an inverter_dyn object in grid-forming mode, will provide DC bus changes and some minor transient detail. A behavioral model of PV cell is adopted here, the advantage of this model is that it only needs parameters of output characteristics of PV cell such as open-circuit voltage ($U_{oc}$), short-circuit current ($I_{sc}$), voltage and current at maximum power operating point ($U_m$ and $I_m$).

The formulas which describe the behavioral model are given as below:

 $\displaystyle{}I=I_{sc}\left[1-C_1\left(\exp{\frac{U-dU}{C_2U_{oc}}}-1\right)\right]+dI$ (1) $\displaystyle{}C_1=\left(1+\frac{I_m}{I_{sc}}-\right)\exp{\frac{-U_m}{C_2U_{oc}}}$ (2) $\displaystyle{}C_2=\left(\frac{U_m}{U_{oc}}-1\right)\left[\ln{1-\frac{I_m}{I_{sc}}}\right]^{-1}$ (3) $\displaystyle{}dU=-b_1U_{oc}(t-t_{ref})$ (4) $\displaystyle{}dI=I_{sc}\left[a_1\frac{S}{S_{ref}}\left(t-t_{ref}\right)+\left(\frac{S}{S_{ref}}-1\right)\right]$ (5)

Where $S_{ref}$ and $t_{ref}$ are light intensity and temperature in standard environment ($S_{ref}=1000\frac{w}{m^2}$, $t_{ref}=25^{\circ}$C), $S$ and $t$ are real light intensity and temperature, $a_1$ and $b_1$ are parameters that used to revise the output characteristics of PV panel in different environment. $a_1$ and $b_1$ are set zero in this instance.

A real PV panel has been modeled according to the formulas above, the output parameters of which are given in Table 1:

Table 1 - Output Parameters of PV Panel
Variable Units Value
$\displaystyle{}U_{oc}$ V 1005
$\displaystyle{}I_{sc}$ A 100
$\displaystyle{}U_{m}$ V 750
$\displaystyle{}I_{m}$ A 84

In GridLAB-D simulation, the PV panel is modeled as a controllable current source, with the light intensity ($S$), temperature ($t$) and voltage of PV panel as inputs. The output of the model is the current of PV panel.

The P-V curve of this PV panel is given in Figure 1, the maximum power is about 1400kW and the voltage at maximum power point is 850V. ($t=25^{\circ}C, S=600\frac{w}{m^2}$).

Figure 1 - P-V Curve of PV Panel