diff --git a/PVPlantSite.py b/PVPlantSite.py
index 242b666..2602f15 100644
--- a/PVPlantSite.py
+++ b/PVPlantSite.py
@@ -182,16 +182,14 @@ def makeSolarDiagram(longitude, latitude, scale=1, complete=False, tz=None):
         import ladybug
         from ladybug import location
         from ladybug import sunpath
-    except:
-        # TODO - remove pysolar dependency
-        # FreeCAD.Console.PrintWarning("Ladybug module not found, using pysolar instead. Warning, this will be deprecated in the future\n")
+    except ImportError:
         ladybug = False
         try:
             import pysolar
-        except:
+        except ImportError:
             try:
                 import Pysolar as pysolar
-            except:
+            except ImportError:
                 FreeCAD.Console.PrintError("The pysolar module was not found. Unable to generate solar diagrams\n")
                 return None
             else:
@@ -361,7 +359,7 @@ def makeWindRose(epwfile, scale=1, sectors=24):
     try:
         import ladybug
         from ladybug import epw
-    except:
+    except ImportError:
         FreeCAD.Console.PrintError("The ladybug module was not found. Unable to generate solar diagrams\n")
         return None
     if not epwfile:
@@ -667,23 +665,22 @@ class _PVPlantSite(ArchSite._Site):
                     self.computeAreas(obj)
 
     def computeAreas(self, obj):
+        """
+        Compute areas, perimeter and volumes.
+        Override to add custom logic after parent computation.
+        """
         ArchSite._Site.computeAreas(self, obj)
-        return
 
         if not obj.Shape:
             return
-
-        if obj.Shape.isNull():
+        if obj.Shape.isNull() or not obj.Shape.isValid() or not obj.Shape.Faces:
             return
-        if not obj.Shape.isValid():
-            return
-        if not obj.Shape.Faces:
-            return
-        if not hasattr(obj, "Perimeter"):  # check we have a latest version site
+        if not hasattr(obj, "Perimeter"):
             return
         if not obj.Terrain:
             return
-        # compute area
+
+        # Compute projected area (horizontal projection of all near-horizontal faces)
         fset = []
         for f in obj.Shape.Faces:
             if f.normalAt(0, 0).getAngle(FreeCAD.Vector(0, 0, 1)) < 1.5707:
@@ -694,13 +691,11 @@ class _PVPlantSite(ArchSite._Site):
             for f in fset:
                 try:
                     pf = Part.Face(Part.Wire(Drawing.project(f, FreeCAD.Vector(0, 0, 1))[0].Edges))
-                except Part.OCCError:
-                    # error in computing the area. Better set it to zero than show a wrong value
-                    if obj.ProjectedArea.Value != 0:
-                        print("Error computing areas for ", obj.Label)
-                        obj.ProjectedArea = 0
-                else:
                     pset.append(pf)
+                except Part.OCCError:
+                    if getattr(obj, 'ProjectedArea', None) and obj.ProjectedArea.Value != 0:
+                        FreeCAD.Console.PrintWarning(f"Error computing projected area for {obj.Label}\n")
+                        obj.ProjectedArea = 0
             if pset:
                 self.flatarea = pset.pop()
                 for f in pset:
@@ -708,28 +703,27 @@ class _PVPlantSite(ArchSite._Site):
                 self.flatarea = self.flatarea.removeSplitter()
                 if obj.ProjectedArea.Value != self.flatarea.Area:
                     obj.ProjectedArea = self.flatarea.Area
-        # compute perimeter
+
+        # Compute perimeter (border edges only)
         lut = {}
         for e in obj.Shape.Edges:
             lut.setdefault(e.hashCode(), []).append(e)
-        l = 0
-        for e in lut.values():
-            if len(e) == 1:  # keep only border edges
-                l += e[0].Length
-        if l:
-            if obj.Perimeter.Value != l:
-                obj.Perimeter = l
-        # compute volumes
-        if obj.Terrain.Shape.Solids:
-            shapesolid = obj.Terrain.Shape.copy()
-        else:
-            shapesolid = obj.Terrain.Shape.extrude(obj.ExtrusionVector)
-        addvol = 0
-        subvol = 0
-        for sub in obj.Subtractions:
-            subvol += sub.Shape.common(shapesolid).Volume
-        for sub in obj.Additions:
-            addvol += sub.Shape.cut(shapesolid).Volume
+        perimeter = sum(e[0].Length for e in lut.values() if len(e) == 1)
+        if perimeter and obj.Perimeter.Value != perimeter:
+            obj.Perimeter = perimeter
+
+        # Compute cut/fill volumes relative to terrain
+        try:
+            if obj.Terrain.Shape.Solids:
+                shapesolid = obj.Terrain.Shape.copy()
+            else:
+                shapesolid = obj.Terrain.Shape.extrude(obj.ExtrusionVector)
+        except Exception:
+            return
+
+        subvol = sum(sub.Shape.common(shapesolid).Volume for sub in obj.Subtractions)
+        addvol = sum(sub.Shape.cut(shapesolid).Volume for sub in obj.Additions)
+
         if obj.SubtractionVolume.Value != subvol:
             obj.SubtractionVolume = subvol
         if obj.AdditionVolume.Value != addvol:
@@ -1056,7 +1050,7 @@ class _ViewProviderSite:
                     if hasattr(vobj.Object,"EPWFile") and vobj.Object.EPWFile:
                         try:
                             import ladybug
-                        except:
+                        except ImportError:
                             pass
                         else:
                             self.windrosenode = makeWindRose(vobj.Object.EPWFile,vobj.SolarDiagramScale)