diff --git a/Utilities/Shading.py b/Utilities/Shading.py
index db0e4e7..656fe4b 100644
--- a/Utilities/Shading.py
+++ b/Utilities/Shading.py
@@ -1,6 +1,7 @@
 import numpy as np
 import pandas as pd
 import logging
+import math
 
 from ladybug_geometry.geometry3d.pointvector import Point3D, Vector3D
 from ladybug_geometry.geometry3d.plane import Plane
@@ -86,13 +87,16 @@ def create_panels(coordinates, c):
     panel_length = c["panel"]["dimensions"]["length"]
     panel_thickness = c["panel"]["dimensions"]["thickness"]
 
+    # if viewed from above, and assumming the roof is a rectangle, the
+    # global origin is at the bottom left corner of the roof
+
     # For a vertical panel:
     # - The vertical direction (panel height) is along the Z-axis.
-    y_axis = Vector3D(0, 0, 1)  # points upward
+    y_axis = Vector3D(0, 1, 0)  # points east, therefore front face is east facing
 
     # - The horizontal direction along the panel's width.
     #   Here, we assume the width runs in the positive X-direction.
-    x_axis = Vector3D(1, 0, 0)  # points east
+    x_axis = Vector3D(1, 0, 0)  # points north
 
     panels = []
     for index, row in coordinates.iterrows():
@@ -100,7 +104,7 @@ def create_panels(coordinates, c):
         panel_origin = Point3D(row["x"], row["y"], row["z"])
 
         # Create the plane for the panel
-        panel_plane = Plane(origin=panel_origin, y_axis=y_axis, x_axis=x_axis)
+        panel_plane = Plane(o=panel_origin, n=y_axis, x=x_axis)
 
         # Create the panel geometry
         panel = Polyface3D.from_box(
@@ -137,3 +141,75 @@ def get_solar_data(c):
     solar_positions = pvlib.solarposition.get_solarposition(times, latitude, longitude)
 
     return solar_positions
+
+
+def calculate_sun_vector(solar_zenith, solar_azimuth):
+    """
+    Calculate the sun vector from solar zenith and azimuth angles.
+    Args:
+        solar_zenith (float): Solar zenith angle in degrees.
+        solar_azimuth (float): Solar azimuth angle in degrees.
+
+    Returns:
+        Vector3D: Sun vector as a 3D vector.
+    """
+    # Convert angles from degrees to radians
+    zenith_rad = math.radians(solar_zenith)
+    azimuth_rad = math.radians(solar_azimuth)
+
+    # Calculate the sun vector components
+    x = math.sin(zenith_rad) * math.cos(azimuth_rad)
+    y = math.sin(zenith_rad) * math.sin(azimuth_rad)
+    z = math.cos(zenith_rad)
+
+    return Vector3D(x, y, z)
+
+
+def compute_array_shading(panels, sun_vector, n_samples=25):
+    """
+    Given a list of panel geometries (Polyface3D) and the sun vector,
+    compute the shading fraction for each panel and return the overall average shading.
+
+    Parameters:
+      panels: List of Polyface3D objects representing the PV panels.
+      sun_vector: Unit Vector3D in the direction of the sun.
+      n_samples: Number of sample points per panel.
+
+    Returns:
+      Dictionary mapping panel index to its shading fraction, and the overall average.
+    """
+    shading_results = {}
+    for i, panel in enumerate(panels):
+        # Define obstacles as all other panels in the array
+        obstacles = [pan for j, pan in enumerate(panels) if j != i]
+        shading_frac = calculate_shading_fraction(
+            panel, sun_vector, obstacles, n_samples=n_samples
+        )
+        shading_results[i] = shading_frac
+    # Compute the overall average shading fraction across all panels:
+    overall_avg = np.mean(list(shading_results.values()))
+    return shading_results, overall_avg
+
+
+def calculate_shading_fraction(c):
+    coordinates = define_grid_layout(c)
+    panels = create_panels(coordinates, c)
+    solar_positions = get_solar_data(c)
+
+    shading_fractions = []
+    for panel in panels:
+        shading_fraction = []
+        for index, row in solar_positions.iterrows():
+            # Get the solar position for the current time step
+            # in a sphere, azimuth is the angle in the x-y plane from the north
+            # and zenith is the angle from the vertical axis
+            solar_zenith = row["apparent_zenith"]
+            solar_azimuth = row["apparent_azimuth"]
+            sun_vector = calculate_sun_vector(solar_zenith, solar_azimuth)
+
+            # Calculate the shading fraction using the panel and solar position
+            shading_fraction.append(panel.shading_fraction(solar_zenith, solar_azimuth))
+
+        shading_fractions.append(shading_fraction)
+
+    return shading_fractions
diff --git a/main.py b/main.py
index 8ea5c27..18beee3 100644
--- a/main.py
+++ b/main.py
@@ -1,7 +1,7 @@
 # %%
 import yaml
 import logging
-from Utilities.Shading import define_grid_layout
+from Utilities.Shading import calculate_shading_fraction
 
 logging.basicConfig(
     level=logging.INFO,
@@ -24,6 +24,6 @@ with open(config_path, "r") as file:
 logger.info("Configuration loaded successfully.")
 logger.debug(f"Configuration: {c}")
 
-coordinates = define_grid_layout(c)
+calculate_shading_fraction(c)
 
 # %%