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--- electrical:solar:shading [2024/11/08 16:11]
frater_secessus [which has observable effects on output]
+++ electrical:solar:shading [2024/11/08 16:30] (current)
frater_secessus [so users try different panel configurations]
@@ Line 36: / Line 36: @@
 For reasons discussed below the string of 36 cells will be subdivided into substrings of cells in series. 2 strings of 18 cells is common((for cost reasons)).  So we can think of this panel
-    ############
+    #########
-    ############
+    #########
-    ############
+    #########
-    ############
+    #########
 straightened out but electrically identical
@@ Line 73: / Line 73: @@
     ################## ##################
-...where the equal sign (=) is a bypass path when needed to prevent damage.
+...where the equal sign ("=") is a bypass path when needed to prevent damage.
@@ Line 100: / Line 100: @@
 ==== so users try different panel configurations ====
+=== parallel ===
+Let's start using both our panels in parallel
+     #########
+     #########
+     #########
+     #########
+     #########
+     #########
+     #########
+     #########
+which, unwound and with bypass diodes, would be
+             =                 =
+    ################## ##################
+             =                 =
+    ################## ##################
-**Before we begin:** solar panels are "current sources";  their voltage pops up into the normal range in any kind of meaningful light(>= 20% [[electrical:solar:output|insolation]]) but current will suffer.
+if we have the same partial shading as before
-Partial shading in this context means:
-  * light is falling on the panel
-  * but not evenly on the panel -- it is different on some cells
-To prevent power from rushing into the shaded string and overheating them, panels have bypass diodes between the strings.  Basically the shaded strings get cut off, electrically speaking, to protect them. In a perfect world each cell would be protect by a lossless, costless diode but that's not possible yet.  :-)
+             =                 =
+    ################## ##################
+             =                 =
+    ################## ####0###00########
+To prevent voltage backing up into a panel from a neighboring panel (or battery bank at night) each //panel// typically has a //blocking diode//. So the complete picture is:
+             =                 =
+    ################## ################## =
+             =                 =
+    ################## ####0###00######## =
+Note:  in most panels the blocking and bypass diodes are identical parts, just installed in different places, in different orientations, and for different purposes.
+=== series ===
+             =                 =                   =                  =
+    ################## ################## = ################## ####0###00######## =
 ===== further reading =====

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