Wire in Series then all wired together in Parallel

ccrisham

I have a victron mppt 100/20 controller I was wondering about doing a series and parallel connection with my 200w 24v pannels

If I do just 2 in series it will be about

75V
5.4A

So was wondering could I just add a 2nd string and get

75V
11A

I dont see why it would not work but I cant find any info on anyone saying not to do it only thing people say is dont go over the max V

Thank you

mike95490

Wiring 4 panels:
2 in series
2 in series
  and then paralleling those 2 groups of panels to get 75V, 11A
would be just fine for most charge controllers.   You have to verify your panels Voc when cold, would
not exceed the max voltage input for you controller.
  Remember,  75V max power,  closer to 95V open circuit on a cool morning.   Many charge controllers
have a sizing tool on their website, to verify you wont exceed the limits

shorthand:   2S2P for your panel arrangement

75V, 11A = 825 watts.   12V = 69A output from controller.  24V = 34A output

Following screen shot shows MPPT controller converting high voltage ( 79.2v) from solar,
to lower voltage & higher amps to the battery

Photowhit

ccrisham said:

I have a victron mppt 100/20 controller I was wondering about doing a series and parallel connection with my 200w 24v pannels

Victron Charge controllers are rated at max input voltage and output amperage. So output is limited to 20 amps, if you have a string of 2 - 200 watt 24 volt nominal panels, you would have an input of 400 watts, but at 12 volt charging around 15 volts, you would have a possiblity of 400 ÷ 15 = 26.66 amps.

So an important question is what is your system/ battery bank voltage?

BB.

Yes, it would work, but the "typical" best case charging current (a few times a year on cool/clear days around solar noon):

• 800 Watt array * 0.77 panel+controller deratings * 1/14.5 volts charging = 42.5 Amps
• 800 Watt array * 0.77 panel+controller deratings * 1/29.0 volts charging = 21.2 Amps

So, with a 20 Amp MPPT controller (max output charging current)--You are losing around 1/2 of the potential array harvest on a 12 volt battery bank.

On a 24 volt battery bank--Pretty much maxing out the 20 Amp charge controller (which is just fine--You are losing only a very small amount of total harvest).

The present controller will work fine--But adding a second array on cool/clear days around noon--You are losing quite a bit of harvest potential. A second 20 amp controller or >~40 Amp MPPT controller would be a better fit long term.

And as Mike says/asks... How cold of weather are you planning on... If you are in seriously cold weather (well below freezing), your array could easily exceed 100 VDC Voc-array (voltage open circuit) limit of your present charge controller.

Need the exact Vmp/Imp/Voc/Isc of your panels and what is the minimum temperature your array is expected to experience?

-Bill

ccrisham

Yes battery V is 24 system  and I am in central FL so temps dont get too cold.  

I was figuring it would work fine with a 24v system 2 sets of 2 x 200W panels

I currently only have 2 of the 200W panels but planning to get more and glad I dont need to get a 2nd controller for that set.

Thank you for your help 

• Maximum Power(Pmax): 200W
• Maximum Power Voltage(Vmp): 37.6V
• Maximum Power Current(Imp): 5.32A
• Open Circuit Voltage(Voc): 45.4V
• Short Circuit Current(Isc): 5.83A
• Maximum System Voltage(Vmax): 1000V DC