ADR PV efficiency model from pvpltools-python

docs/examples/adr-pv-module-efficiency/README.rst

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+ADR Model for PV Module Efficiency
+----------------------------------
+

docs/examples/adr-pv-module-efficiency/plot_fit_to_matrix.py

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+"""
+Obtaining ADR model parameters from IEC 61853 matrix measurements
+=================================================================
+
+There's a fitting function provided in pvlib to do exactly that.
+
+(WORK IN PROGRESS)
+
+Since PV module efficiency varies with irradiance and temperature
+what better way to train a model than using efficiency measurement
+over a broad range of temperature and irradiance levels?
+The standard IEC 61853-1 defines a standard matrix of conditions
+for such measurements and this example shows how the ADR model
+parameters can be determined with just a few lines of code using
+functions in pvlib-python.
+
+"""
+
+from io import StringIO
+import pandas as pd
+import matplotlib.pyplot as plt
+
+from pvlib.pvefficiency import adr, fit_pvefficiency_adr
+
+# %% The text on this line is not displayed
+#
+# Here are some matrix measurements:
+#
+
+iec61853data = '''
+    irradiance  temperature     p_mp
+0          100         15.0   30.159
+1          200         15.0   63.057
+2          400         15.0  129.849
+3          600         15.0  197.744
+4          800         15.0  264.825
+5         1000         15.0  330.862
+6          100         25.0   29.250
+7          200         25.0   61.137
+8          400         25.0  126.445
+9          600         25.0  192.278
+10         800         25.0  257.561
+11        1000         25.0  322.305
+12        1100         25.0  354.174
+13         100         50.0   26.854
+14         200         50.0   56.698
+15         400         50.0  117.062
+16         600         50.0  177.959
+17         800         50.0  238.626
+18        1000         50.0  298.954
+19        1100         50.0  328.413
+20         100         75.0   24.074
+21         200         75.0   51.103
+22         400         75.0  106.546
+23         600         75.0  162.966
+24         800         75.0  218.585
+25        1000         75.0  273.651
+26        1100         75.0  301.013
+'''
+df = pd.read_csv(StringIO(iec61853data), delim_whitespace=True)
+
+# %%
+#
+# Now calculate the normalized or relative efficiency values
+# and use the fitting function to determine the parameters.
+# The parameters (shown below) can now be used to
+# simulate the module operating in a PV system.
+#
+
+P_REF = 322.305   # (W) STC value from the table above
+G_REF = 1000.     # (W/m2)
+
+df['eta_rel'] = (df['p_mp'] / P_REF) / (df['irradiance'] / G_REF)
+
+adr_params = fit_pvefficiency_adr(df['irradiance'], df['temperature'],
+                                  df['eta_rel'])
+
+for k, v in adr_params.items():
+    print('%-5s = %7.4f' % (k, v))
+
+# %%
+#
+# Compare the model output to the original measurements.
+# The chart below shows minor differences but due to their random nature
+# they are most likely evidence of the limitations of measurement accuracy.
+#
+
+eta_rel_adr = adr(df['irradiance'], df['temperature'], **adr_params)
+
+plt.figure()
+plt.plot(df['irradiance'], df['eta_rel'], 'oc', ms=8)
+plt.plot(df['irradiance'], eta_rel_adr, '.k')
+plt.legend(['Lab measurements', 'ADR model fit'])
+plt.xlabel('Irradiance [W/m²]')
+plt.ylabel('Relative efficiency [-]')
+plt.grid(alpha=0.5)
+plt.show()
+
+# %%
+#
+# References
+# ----------
+# .. [1] A. Driesse and J. S. Stein, "From IEC 61853 power measurements
+#    to PV system simulations", Sandia Report No. SAND2020-3877, 2020.
+#
+# .. [2] A. Driesse, M. Theristis and J. S. Stein, "A New Photovoltaic Module
+#    Efficiency Model for Energy Prediction and Rating," in IEEE Journal
+#    of Photovoltaics, vol. 11, no. 2, pp. 527-534, March 2021,
+#    doi: 10.1109/JPHOTOV.2020.3045677.
+#

docs/examples/adr-pv-module-efficiency/plot_simulate_system.py

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+"""
+Simulating PV systems using the ADR module efficiency model
+===========================================================
+
+Time series processing with the ADR model is fast and ... efficient!
+
+This example reads a TMY3 weather file, and runs a basic simulation
+on a fixed latitude-tilt system.
+Efficiency is independent of system size, so adjusting the system
+capacity is just a matter of setting the desired value, e.g. P_STC = 5000.
+
+"""
+
+import os
+import pandas as pd
+import matplotlib.pyplot as plt
+
+import pvlib
+from pvlib import iotools, location, pvefficiency
+from pvlib.irradiance import aoi, get_total_irradiance
+
+# %%
+#
+# Read a TMY3 file containing weather data and select needed columns
+#
+
+PVLIB_DIR = pvlib.__path__[0]
+DATA_FILE = os.path.join(PVLIB_DIR, 'data', '723170TYA.CSV')
+
+tmy, metadata = iotools.read_tmy3(DATA_FILE, coerce_year=1990)
+
+df = pd.DataFrame({'ghi': tmy['GHI'], 'dhi': tmy['DHI'],
+                   'dni': tmy['DNI'], 'dni_extra': tmy['ETRN'],
+                   'temp_air': tmy['DryBulb'], 'wind_speed': tmy['Wspd'],
+                   })
+
+# %%
+#
+# Shift timestamps to middle of hour and then calculate sun positions
+#
+
+df.index = df.index - pd.Timedelta(minutes=30)
+
+loc = location.Location.from_tmy(metadata)
+solpos = loc.get_solarposition(df.index)
+
+# %%
+#
+# Determine  total irradiance on a fixed-tilt array
+#
+
+TILT = metadata['latitude']
+ORIENT = 180
+
+df['aoi'] = aoi(TILT, ORIENT, solpos.apparent_zenith, solpos.azimuth)
+
+total_irrad = get_total_irradiance(TILT, ORIENT,
+                                   solpos.apparent_zenith, solpos.azimuth,
+                                   df.dni, df.ghi, df.dhi, df.dni_extra)
+
+df['poa_global'] = total_irrad.poa_global
+
+# %%
+#
+# Estimate the expected operating temperature of the PV modules
+#
+
+df['temp_pv'] = pvlib.temperature.faiman(df.poa_global, df.temp_air,
+                                         df.wind_speed)
+
+# %%
+#
+# Now we're ready to calculate PV array DC output power based
+# on POA irradiance and PV module operating temperature.
+# Among the models available in pvlib-python to do this are:
+# - PVWatts
+# - SAPM
+# - single-diode model variations
+# - and now also the ADR PV efficiency model
+#
+# Simulation is done in two steps:
+# - first calculate efficiency using the ADR model,
+# - then convert (scale up) efficiency to power.
+#
+
+# Borrow the ADR model parameters from the other example:
+
+adr_params = {'k_a': 0.99879,
+              'k_d': -5.85188,
+              'tc_d': 0.01939,
+              'k_rs': 0.06962,
+              'k_rsh': 0.21036
+              }
+
+df['eta_rel'] = pvefficiency.adr(df['poa_global'], df['temp_pv'], **adr_params)
+
+# Set the desired array size:
+P_STC = 5000.   # (W)
+# and the irradiance level needed to achieve this output (
+G_STC = 1000.   # (W/m2)
+
+df['p_mp'] = P_STC * df['eta_rel'] * (df['poa_global'] / G_STC)
+
+# %%
+#
+# Show how power and efficiency vary with both irradiance and temperature
+#
+
+plt.figure()
+pc = plt.scatter(df['poa_global'], df['eta_rel'], c=df['temp_pv'], cmap='jet')
+plt.colorbar(label='Temperature [C]', ax=plt.gca())
+pc.set_alpha(0.25)
+plt.grid(alpha=0.5)
+plt.ylim(0.48)
+plt.xlabel('Irradiance [W/m²]')
+plt.ylabel('Relative efficiency [-]')
+plt.show()
+
+plt.figure()
+pc = plt.scatter(df['poa_global'], df['p_mp'], c=df['temp_pv'], cmap='jet')
+plt.colorbar(label='Temperature [C]', ax=plt.gca())
+pc.set_alpha(0.25)
+plt.grid(alpha=0.5)
+plt.xlabel('Irradiance [W/m²]')
+plt.ylabel('Array power [W]')
+plt.show()
+
+# %%
+#
+# One day:
+#
+
+DEMO_DAY = '1990-08-05'
+
+plt.figure()
+plt.plot(df['p_mp'][DEMO_DAY])
+plt.xticks(rotation=30)
+plt.ylabel('Power [W]')
+plt.show()
+
+# %%
+#
+# References
+# ----------
+# .. [1] A. Driesse and J. S. Stein, "From IEC 61853 power measurements
+#    to PV system simulations", Sandia Report No. SAND2020-3877, 2020.
+#
+# .. [2] A. Driesse, M. Theristis and J. S. Stein, "A New Photovoltaic Module
+#    Efficiency Model for Energy Prediction and Rating," in IEEE Journal
+#    of Photovoltaics, vol. 11, no. 2, pp. 527-534, March 2021,
+#    doi: 10.1109/JPHOTOV.2020.3045677.
+#

docs/sphinx/source/reference/pv_modeling.rst

@@ -187,3 +187,5 @@ Other
 
    pvsystem.retrieve_sam
    pvsystem.scale_voltage_current_power
+   pvefficiency.adr
+   pvefficiency.fit_pvefficiency_adr