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--- electrical:solar:series_vs_parallel [2020/05/09 12:33]
frater_secessus [Series and Parallel solar arrays]
+++ electrical:solar:series_vs_parallel [2021/06/06 15:01]
frater_secessus [Series-Parallel]
@@ Line 1: / Line 1: @@
 ====== Series and Parallel solar arrays ======
-Broadly speaking, parallel arrays of nominal 12v [[electrical:solar:panels|panels]] are used with [[electrical:solar:charge_controller#pwm]] [[electrical:solar:charge controller|charge controllers]] and serial arrays or higher nominal voltage panels used and [[electrical:solar:charge_controller#mppt|MPPT]] controllers.
+Generally speaking, parallel arrays of nominal 12v [[electrical:solar:panels|panels]] are used with [[electrical:solar:charge_controller#pwm]] [[electrical:solar:charge controller|charge controllers]] and serial arrays or higher nominal voltage panels are used with [[electrical:solar:charge_controller#mppt|MPPT]] controllers.
@@ Line 16: / Line 16: @@
     * more efficient than parallel when **mixing PV of same Imp but different Vmp**((https://www.youtube.com/watch?v=JfzT8u205co))
     * slightly better than parallel when **mixing PV of different Imp //and// Vmp**((https://www.youtube.com/watch?v=ZAKTMSEHfk8))
+    * higher voltages can help overcome minimum delta requirements to get the MPPT algo running (Victron controllers, for example,  require +5v to start and +1v to maintain MPPT).
   * CON
     * series arrays can generate quite **high operating voltages**.  Be sure your controller can handle the VoC with edge effect.
@@ Line 41: / Line 42: @@
 ===== Series-Parallel =====
-FIXME
+Consider this scenario:
+  * 4 panels
+    * 150w
+    * Vmp == 19v
+    * Voc == 22.8
+    * Imp == 7.9A
+  * MPPT controller with 60v maximum input voltage
+A fully-series configuration ([[electrical:12v:parallel_serial|1p4s]]) would have a **Voc of 91.2v**, greatly exceeding the controller's input spec of 60v, and it's common to want to have 20% voltage headroom above Voc.
+A fully-parallel configuration (4p1s) would require 3x 2-into-1 MC4 adapters or 1x 4-into-1 adapter.  The wiring from the array would need to carry 30A+ to the controller,  necessitating heavier wiring that would cost more and might not even fit the controller terminals.  It might be unable to charge at all under extreme low-light conditions.
+A compromise might be series-parallel array (2p2s) with 45.6Voc and ~16A.  This would require 1x 2-into-1 MC4 adapter to combine the two serial strings.

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