Series or Parallel PV Panel Wiring?

[Zulu]

I'm curious for those of you with solar setups . . . are you using Series or Parallel panel wiring? Why?

[Chad Heiser]

I’m using both series and parallel in my setup and do so often in other setups.  I also do series only setups and parallel only setups.  It really depends on what your needs are.  If you have small wire already in place coming down from the roof then a series set up can take advantage of that small wire by upping the voltage and keeping the amperage low.  If you are running your own new wire then you can use larger wire to handle higher amperage and keep your panels in parallel or some combination of series parallel.

In the past, parallel had a big advantage over series in the RV world because PWM solar controllers were limited on the voltage they could handle and older panels without bypass diodes could be severely negatively affected by shading a single panel (or part of one) in a series string.  In today’s world of MPPT solar controllers, the higher voltage a series string of panels can provide can be advantageous.  Also with bypass diodes common in most modern solar panels, shading is no longer the killer it used to be in a series string of panels.

i do a lot of series pairs pairs of panels and then run those series pairs in parallel (like six volt batteries run in series parallel to make 12 volt).  This gives me higher voltage to the MPPT controller that can be converter to amperage to the batteries and also reduces potential shading issues for panels in close proximity to one another.  It also builds some redundancy into the solar array in case a panel or connection fails.  If there is a failure, then only that series pair will be affected and the other series pairs will continue producing.  Of course this configuration requires an even number of panels.

[Zulu]

1 hour ago, Chad Heiser said:

In the past, parallel had a big advantage over series in the RV world because PWM solar controllers were limited on the voltage they could handle and older panels without bypass diodes could be severely negatively affected by shading a single panel (or part of one) in a series string.  In today’s world of MPPT solar controllers, the higher voltage a series string of panels can provide can be advantageous.

Interesting. My 1st solar install was series/parallel, my 2nd install was parallel, and my soon-to-be 3rd install will be series.

All things being equal (PV panels, charge controllers, etc), my 1st series/parallel install always seemed to yield superior results over the parallel one. Hopefully, the series install will be the best. We'll see.

Edited May 13, 2022 by Zulu

[Chad Heiser]

18 minutes ago, Zulu said:

Interesting. My 1st solar install was series/parallel, my 2nd install was parallel, and my soon-to-be 3rd install will be series.

All things being equal (PV panels, charge controllers, etc), my 1st series/parallel install always seemed to yield superior results over the parallel one. Hopefully, the series install will be the best. We'll see.

With an MPPT controller, a series/parallel installation will give better results than a straight parallel configuration.  The MPPT controller can convert the excess voltage into current for the batteries.

[oldjohnt]

7 hours ago, Zulu said:

are you using Series or Parallel panel wiring? Why?

Zulu, I'm NOT an expert but FWIW I pretty much agree with the other fine gents and here's my response:

 Good question, like others I have used BOTH and you ask why ??

1) When I started several years ago using PWM charge controllers that were ONLY appropriate for 12 or 24 Volt panels, I had to use parallel connection for 24 volt panels so as NOT to exceed the max PV input controller voltage.

2) When I used a couple 12 Volt Panels I wired in series to increase voltage thereby reducing current in the conductors from the panels down to my PWM charge controller

3) Nowadays or then when using an MPPT charge controller they are rated for the maximum PV Input Voltage and current and can accept higher PV Input (NOT limited to 12 or 24) WHICH ALLOWS/FAVORS SERIES PANEL CONNECTIONS to reduce current (less line voltage drop and wasted I Squared R heat energy losses) from panels down to controller.

IN ESSENCE the answer depends on:  The max PV input voltage your controller will accept (50 Volts, 100 volts ?),,,,,,,,,,,,How many panels you have and their voltage and current rating,,,,,,,,,,,,What size wire you have from panels down to controller,,,,,,,,,As I'm sure you already know, panels in series adds voltage while in parallel current adds and its good to reduce line voltage drop which means less current (caused by higher series voltaqe)   

4) Now I use Series/Parallel and in general when using multiple panels in series (say 2, 4 or more etc) that works to raise the voltage up to the controllers max. Example: When using a controller that accepts 100 Volts PV input and having four matched 24 volt panels, wire two panels in PARALLEL and connect that in SERIES with the two other 24 volt panels in parallel. I have used such a series/parallel connection with four 24 volt panels and subject to sunlight my controller might see 70+ volts   

The answer depends on how many panels,,,,,,,,,their ratings,,,,,,,,,,,,your controller specs...Im sure you will figure it out

Best wishes, listen to the experts not me

John T

[Randyretired]

With series configurations it is important to not exceed the maximum voltage of the controller.  The calculations should include the increase in voltage panels have in cold environments. I like to leave plenty of head room for this.  Most controllers have little if any room to exceed the voltage limits.  Most manufactures state that the controllers are most efficient with voltages that are just above what is necessary  for the MPPT controller to function.  However, the loss at higher voltage is minimal as these controllers are efficient so the savings in wire costs are often the deciding factor.  One word of caution, high voltage DC is dangerous and can be deadly.  Use extreme caution and safe installation methods.  Another problem with high voltage DC is the arcing that occurs when switched.  This can and will weld contacts.  Use of quality breakers designed for this and avoid switching during high current is essential.

[Darryl&Rita]

Both, depending on the math. Yes, math, like you learned in school.

[hemsteadc]

Series.  Much easier wiring, higher voltage less line loss,smaller wire,  expensive controller handles it.