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--- electrical:solar:series_vs_parallel [2019/02/01 20:15]
frater_secessus [Series and Parallel solar arrays]
+++ electrical:solar:series_vs_parallel [2024/03/09 11:00] (current)
frater_secessus [further reading] marine
@@ Line 1: / Line 1: @@
 ====== Series and Parallel solar arrays ======
-In general, 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 with higher nominal voltage panels and [[electrical:solar:charge_controller#mppt|MPPT]] controllers.
+===== TL;DR =====
+  * With [[electrical:solar:charge_controller#mppt|MPPT]] solar charge controllers and 12v house battery bank there is often //little practical difference between parallel and series solar arrays//.
+  * [[electrical:solar:charge_controller#pwm|PWM controllers]] run arrays of the same nominal voltage as their battery bank:  12v and 12v, 24v and 24v.
+  * //generally speaking//, parallel panels will perform better in [[electrical:solar:shading|partial shade]] than series. [but don't shade your panels in the first place -- secessus]
+  * as with other [[electrical:12v:parallel_serial|series/parallel arrangements]], series increases voltage and parallel increases current.
+  * series arrays can reduce capital costs in some circumstances
+  * series/parallel arrangements are described with ''xPxS'' nomenclature:
+    * 2 panels in parallel would be 2P1S
+    * 2 panels in series would be 1P2S
+    * 4 panels in series-parallel would be 2P2S
@@ Line 10: / Line 20: @@
   * PRO
     * higher PV voltage can run in relatively **thinner wires** to the charge controller
-    * serial connections can provide **some charging in partial shade situations** where lower voltage parallel or single-panel connections might not.  Imagine two nominal 12v panels running at 11v in heavy cover:((due to MPPT's response to shading))  the series arrangement might yield ~22v (battery charging) instead of 11v (voltage too low to charge battery).  This also happens in low, even light (like dusk or dawn) but the amount of power harvestable at those times is so low as to be of little practical use.
+    * serial connections can provide **some charging in low light situations** where lower voltage parallel or single-panel connections might not.  Imagine two nominal 12v panels running at 11v at sunrise;   the series arrangement might yield ~22v (battery charging) instead of 11v (voltage too low to charge battery).  Note that power harvestable at those times may be quite low.
+    * higher-voltage serial configurations with MPPT controllers may provide [[electrical:solar:shading#exceptionhigh_voltage_strings_mppt|more power under partial shading]]
     * higher voltages **work well with MPPT controllers**
     * higher voltages can **charge higher voltage battery systems** like 24v.
     * 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.
     * **requires MPPT charger** to get full use of high-voltage arrays under normal conditions.
     * thin film panels are generally not recommended for use in serial arrays
-    * **more susceptible to partial shading** problems than parallel
+    * short serial strings are **more susceptible to partial shading** losses than parallel
@@ Line 40: / Line 52: @@
 ===== Series-Parallel =====
+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.   Voltage is low enough for the controller, but high enough to allow low-light charging and the use of lighter wiring.
+===== further reading =====
+  * [[https://www.explorist.life/solar-panels-series-vs-parallel/|Solar Panels – Series vs Parallel]] by Explorist Life
+  * [[https://www.youtube.com/watch?v=1s2gsKWqyjM|How To Wire Solar Panels In Series vs Parallel -- For Beginners]]
+  * [[https://www.cruisersforum.com/forums/f14/shading-serial-vs-parallel-this-time-with-data-284237.html|testing series vs parallel in a marine environment]]

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