Floating PV gallery example

docs/examples/floating-pv/README.rst

@@ -0,0 +1,2 @@
+Floating PV Systems Modelling
+-----------------------------

docs/examples/floating-pv/plot_floating_pv_cell_temperature.py

@@ -0,0 +1,231 @@
+r"""
+Temperature modeling for floating PV
+================================================
+
+This example uses the PVSyst temperature model to calculate
+cell temperature for floating photovoltaic (FPV) systems.
+
+One of the primary benefits attributed to FPV systems is the potential
+for lower operating temperatures, which are expected to increase the
+operating efficiency. In general, the temperature at which a photovoltaic
+module operates is influenced by various factors including solar radiation,
+ambient temperature, wind speed and direction, and the characteristics of the
+cell and module materials, as well as the mounting structure.
+
+A popular model for calculating PV cell temperature is the
+empirical heat loss factor model suggested by Faiman
+(:py:func:`pvlib.temperature.faiman`). A modified version of this model is
+has been proposed by PVSyst (:py:func:`~pvlib.temperature.pvsyst_cell`).
+The PVSyst model for cell temperature :math:`T_{C}` is given by:
+
+.. math::
+    :label: pvsyst
+
+    T_{C} = T_{a} + \frac{\alpha \cdot E \cdot (1 - \eta_{m})}{U_{c} + U_{v} \cdot WS},
+
+where :math:`E` is the plane-of-array irradiance, :math:`T_{a}` is the
+ambient air temperature, :math:`WS` is the wind speed, :math:`\alpha` is the
+absorbed fraction of the incident irradiance, :math:`\eta_{m}` is the
+electrical efficiency of the module, :math:`U_{c}` is the wind-independent heat
+loss coefficient, and :math:`U_{v}` is the wind-dependent heat loss coefficient.
+It should be noted that in many cases, similar to land-based PV systems,
+the wind-dependent heat loss coefficient (:math:`U_{v}`) can be set to zero,
+and the denominator is thus reduced to a single combined U-value
+(:math:`U_{c}`).
+
+However, the default heat loss coefficient values of the PVSyst model were
+specified for land-based PV systems and are not necessarily representative
+of FPV systems.
+
+For FPV systems, the module's operating temperature, much like in land-based
+systems, is mainly influenced by the mounting structure (which significantly
+affects both U-value coefficients), wind, and air temperature. Thus, factors
+that help reduce operating temperatures in such systems include lower air
+temperatures and changes in air flow beneath the modules (wind/convection).
+In some designs, where the modules are in direct thermal contact with water,
+cooling effectiveness is largely dictated by the water temperature.
+
+Systems with closely packed modules and restricted airflow behind the modules
+generally exhibit lower heat loss coefficients compared to those with better
+airflow behind the modules.
+
+The table below gives heat loss coefficients derived for different FPV systems
+and locations as found in the literature. It should be noted that, for some
+systems, there are two sets of coefficients, where the second set uses only
+one heat loss coefficient (i.e., only :math:`U_{c}`).
+
+.. table:: Heat transfer coefficients for different PV systems
+   :widths: 40 15 15 15 15
+
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | System                   | Location    |:math:`U_{c}`                   | :math:`U_{v}`                          | Reference |
+   |                          |             |:math:`[\frac{W}{m^2 \cdot K}]` | :math:`[\frac{W}{m^3 \cdot K \cdot s}]`|           |
+   +==========================+=============+================================+========================================+===========+
+   | - Monofacial module      | Netherlands | 24.4                           | 6.5                                    | [1]_      |
+   | - Open structure         |             |                                |                                        |           |
+   | - Two-axis tracking      |             | 57                             | 0                                      |           |
+   | - Small water footprint  |             |                                |                                        |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | Netherlands | 25.2                           | 3.7                                    | [1]_      |
+   | - Closed structure       |             |                                |                                        |           |
+   | - Large water footprint  |             | 37                             | 0                                      |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | Singapore   | 34.8                           | 0.8                                    | [1]_      |
+   | - Closed structure       |             |                                |                                        |           |
+   | - Large water footprint  |             | 36                             | 0                                      |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | Singapore   | 18.9                           | 8.9                                    | [1]_      |
+   | - Closed structure       |             |                                |                                        |           |
+   | - Medium water footprint |             | 41                             | 0                                      |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | Singapore   | 35.3                           | 8.9                                    | [1]_      |
+   | - Open structure         |             |                                |                                        |           |
+   | - Free-standing          |             | 55                             | 0                                      |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | Norway      | 71                             | 0                                      | [2]_      |
+   | - In contact with water  |             |                                |                                        |           |
+   | - Calculated using water |             |                                |                                        |           |
+   |   temperature as         |             |                                |                                        |           |
+   |   :math:`T_{amb}`        |             |                                |                                        |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Monofacial module      | South Italy | 31.9                           | 1.5                                    | [3]_      |
+   | - Open structure         |             |                                |                                        |           |
+   | - Free-standing          |             |                                |                                        |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+   | - Bifacial module        | South Italy | 35.2                           | 1.5                                    | [3]_      |
+   | - Open structure         |             |                                |                                        |           |
+   | - Free-standing          |             |                                |                                        |           |
+   +--------------------------+-------------+--------------------------------+----------------------------------------+-----------+
+
+References
+----------
+.. [1] Dörenkämper M., Wahed A., Kumar A., de Jong M., Kroon J., Reindl T.
+    (2021), 'The cooling effect of floating PV in two different climate zones:
+    A comparison of field test data from the Netherlands and Singapore'
+    Solar Energy, vol. 214, pp. 239-247, :doi:`10.1016/j.solener.2020.11.029`.
+
+.. [2] Kjeldstad T., Lindholm D., Marstein E., Selj J. (2021), 'Cooling of
+    floating photovoltaics and the importance of water temperature', Solar
+    Energy, vol. 218, pp. 544-551, :doi:`10.1016/j.solener.2021.03.022`.
+
+.. [3] Tina G.M., Scavo F.B., Merlo L., Bizzarri F. (2021), 'Comparative
+    analysis of monofacial and bifacial photovoltaic modules for floating
+    power plants', Applied Energy, vol 281, pp. 116084,
+    :doi:`10.1016/j.apenergy.2020.116084`.
+"""  # noqa: E501
+
+# %%
+# Read example weather data
+# ^^^^^^^^^^^^^^^^^^^^^^^^^
+# Read weather data from a TMY3 file and calculate the solar position and
+# the plane-of-array irradiance.
+
+import pvlib
+import matplotlib.pyplot as plt
+from pathlib import Path
+
+# Assume a FPV system on a lake with the following specifications
+tilt = 30  # degrees
+azimuth = 180  # south-facing
+
+# Datafile found in the pvlib distribution
+data_file = Path(pvlib.__path__[0]).joinpath('data', '723170TYA.CSV')
+
+tmy, metadata = pvlib.iotools.read_tmy3(
+    data_file, coerce_year=2002, map_variables=True
+)
+tmy = tmy.filter(
+    ['ghi', 'dni', 'dni_extra', 'dhi', 'temp_air', 'wind_speed', 'pressure']
+)  # remaining columns are not needed
+tmy = tmy['2002-06-06 00:00':'2002-06-06 23:59']  # select period
+
+solar_position = pvlib.solarposition.get_solarposition(
+    # TMY timestamp is at end of hour, so shift to center of interval
+    tmy.index.shift(freq='-30T'),
+    latitude=metadata['latitude'],
+    longitude=metadata['longitude'],
+    altitude=metadata['altitude'],
+    pressure=tmy['pressure'] * 100,  # convert from millibar to Pa
+    temperature=tmy['temp_air'],
+)
+solar_position.index = tmy.index  # reset index to end of the hour
+
+# Albedo calculation for inland water bodies
+albedo = pvlib.albedo.inland_water_dvoracek(
+    solar_elevation=solar_position['elevation'],
+    surface_condition='clear_water_no_waves'
+)
+
+# Use transposition model to find plane-of-array irradiance
+irradiance = pvlib.irradiance.get_total_irradiance(
+    surface_tilt=tilt,
+    surface_azimuth=azimuth,
+    solar_zenith=solar_position['apparent_zenith'],
+    solar_azimuth=solar_position['azimuth'],
+    dni=tmy['dni'],
+    dni_extra=tmy['dni_extra'],
+    ghi=tmy['ghi'],
+    dhi=tmy['dhi'],
+    albedo=albedo,
+    model='haydavies'
+)
+
+# %%
+# Calculate and plot cell temperature
+# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+# The temperature of the PV cell is calculated for lake-based floating PV
+# systems.
+
+# Make a dictionary containing all the sets of coefficients presented in the
+# above table.
+heat_loss_coeffs = {
+    'open_structure_small_footprint_tracking_NL': [24.4, 6.5, 'C0', 'solid'],
+    'open_structure_small_footprint_tracking_NL_2': [57, 0, 'C0', 'dashed'],
+    'closed_structure_large_footprint_NL': [25.2, 3.7, 'C1', 'solid'],
+    'closed_structure_large_footprint_NL_2': [37, 0, 'C1', 'dashed'],
+    'closed_structure_large_footprint_SG': [34.8, 0.8, 'C2', 'solid'],
+    'closed_structure_large_footprint_SG_2': [36, 0, 'C2', 'dashed'],
+    'closed_structure_medium_footprint_SG': [18.9, 8.9, 'C3', 'solid'],
+    'closed_structure_medium_footprint_SG_2': [41, 0, 'C3', 'dashed'],
+    'open_structure_free_standing_SG': [35.3, 8.9, 'C4', 'solid'],
+    'open_structure_free_standing_SG_2': [55, 0, 'C4', 'dashed'],
+    'in_contact_with_water_NO': [71, 0, 'C5', 'solid'],
+    'open_structure_free_standing_IT': [31.9, 1.5, 'C6', 'solid'],
+    'open_structure_free_standing_bifacial_IT': [35.2, 1.5, 'C7', 'solid'],
+    'default_PVSyst_coeffs_for_land_systems': [29.0, 0, 'C8', 'solid']
+}
+
+# Plot the cell temperature for each set of the above heat loss coefficients
+for coeffs in heat_loss_coeffs:
+    T_cell = pvlib.temperature.pvsyst_cell(
+        poa_global=irradiance['poa_global'],
+        temp_air=tmy['temp_air'],
+        wind_speed=tmy['wind_speed'],
+        u_c=heat_loss_coeffs[coeffs][0],
+        u_v=heat_loss_coeffs[coeffs][1]
+    )
+    # Convert Dataframe Indexes to Hour format to make plotting easier
+    T_cell.index = T_cell.index.strftime("%H")
+    plt.plot(T_cell, label=coeffs, c=heat_loss_coeffs[coeffs][2],
+             ls=heat_loss_coeffs[coeffs][3], alpha=0.8)
+
+plt.xlabel('Hour')
+plt.ylabel('PV cell temperature [°C]')
+plt.ylim(10, 45)
+plt.xlim('06', '20')
+plt.grid()
+plt.legend(loc='upper left', frameon=False, ncols=2, fontsize='x-small',
+           bbox_to_anchor=(0, -0.2))
+plt.tight_layout()
+plt.show()
+
+# %%
+# The figure above illustrates the necessity of choosing appropriate heat loss
+# coefficients when using the PVSyst model for calculating the cell temperature
+# for floating PV systems. A difference of up to 10.3 °C was obtained when
+# using the default PVSyst coefficients versus using coefficients for systems
+# where panels are in contact with water.
+#
+# It should be noted that, using the single combined U-value versus the
+# :math:`U_c` and :math:`U_v` gives significantly different results, even
+# when using the coefficients derived from the same system.

docs/sphinx/source/whatsnew/v0.11.1.rst

@@ -25,12 +25,16 @@ Testing
 
 Documentation
 ~~~~~~~~~~~~~
-
+* Added gallery example on calculating cell temperature for
+  floating PV. (:pull:`2110`)
 
 Requirements
 ~~~~~~~~~~~~
 
 
 Contributors
 ~~~~~~~~~~~~
+* Ioannis Sifnaios (:ghuser:`IoannisSifnaios`)
+* Leonardo Micheli (:ghuser:`lmicheli`)
 * Echedey Luis (:ghuser:`echedey-ls`)
+