diff --git a/bifacial_radiance/main.py b/bifacial_radiance/main.py
index 5ae244c6..b597eb5e 100644
--- a/bifacial_radiance/main.py
+++ b/bifacial_radiance/main.py
@@ -4228,7 +4228,7 @@ def _checkSensors(sensors):
 
         xstartfront = x1 + x2 + x3 + originx
         xstartback = x1 + x2 + x4 + originx
-
+        
         ystartfront = y1 + y2 + y3 + originy
         ystartback = y1 + y2 + y4 + originy
 
@@ -4291,10 +4291,22 @@ def _checkSensors(sensors):
                 
             firstsensorxstartfront = xstartfront+xinc_front
             firstsensorxstartback = xstartback+xinc_back
-            firstsensorystartfront = ystartfront+yinc_front
-            firstsensorystartback = ystartback+yinc_back
-            firstsensorzstartfront = zstartfront + zinc_front
-            firstsensorzstartback = zstartback + zinc_back
+            # check to make sure sensorsy don't line up with gaps in between cellModule
+            if ((getattr(scene.module, 'cellModule', None)) and
+                (sensorsy_front == scene.module.cellModule.numcellsy-1)):
+                firstsensorystartfront = ystartfront+yinc_front/2
+                firstsensorzstartfront = zstartfront + zinc_front/2
+            else:
+                firstsensorystartfront = ystartfront+yinc_front
+                firstsensorzstartfront = zstartfront + zinc_front
+            if ((getattr(scene.module, 'cellModule', None)) and
+                (sensorsy_back == scene.module.cellModule.numcellsy-1)):
+                firstsensorystartback = ystartback+yinc_back/2
+                firstsensorzstartback = zstartback + zinc_back/2
+            else:
+                firstsensorystartback = ystartback+yinc_back
+                firstsensorzstartback = zstartback + zinc_back
+
         
             ## Correct positions for sensorsx other than 1
             # TODO: At some point, this equations can include the case where 
diff --git a/docs/sphinx/source/whatsnew/pending.rst b/docs/sphinx/source/whatsnew/pending.rst
index 5f341b33..198beb94 100644
--- a/docs/sphinx/source/whatsnew/pending.rst
+++ b/docs/sphinx/source/whatsnew/pending.rst
@@ -29,6 +29,7 @@ Bug fixes
 * Fixed a leap year bug in   :py:func:`~bifacial_radiance.RadianceObj.readWeatherFile` that crashed if epwfiles are loaded that include leap year data (like Feb. 28 2020). (:issue:`552`)
 * Bug fix in :py:func:`bifacial_radiance.load.cleanResult` that wouldn't work with files created when front and rear scan are different lengths.  (:issue:`419`)
 * GUI bug fixes where the sensorsy was not loading correctly, module .rad file was not being re-written, and an invalid default timestamp is used. 
+* Bug fix in :py:func:`bifacial_radiance.AnalysisObj.moduleAnalysis` when sensorsY equals numCellsy-1 and the scan lines up in the gaps between cells.  shift scan by half a cell.
 
 Documentation
 ~~~~~~~~~~~~~~