How to connect 18-150watt panel and six 75 watt panel?

vtmaps said:

We need to know the specs on each of the panels.   --vtMaps

vtmaps said:

The number for the 75 watt panel are not correct.  Vmp X Imp = watts.  11.75 volts X 2.19 amps = 25.7 watts.

--vtMaps

BB. said:

What battery bank voltage are you trying to run? (12/24/48 volt or something else)?

What solar charge controller are you (trying) to run? Is it an MPPT (maximum power point tracking) or PWM (Plus width modulation)?

Those panels do not map well to 12 or 24 volt battery banks (typically Vmp~18 volts for 12 volt bank and Vmp~36 volts for a 24 volt battery bank). With MPPT type charge controller, you can go >>Vmp nominal for your battery banks (MPPT controllers will take "high voltage/low current" and efficiently down convert to "low voltage/high current" needed to charge the battery bank (within capabilities of the MPPT controller's ratings).

-Bill

BB. said:

It looks like you would put 9x 150 Watt panels in series, 2x parallel strings.

150 watt panel : size : 1125*982 mm , cell : 48 , Voc : 28.7v , Vmp : 23.5v , Isc : 7.02A , Imp: 6.38A
75 watt panel : Size : 1125*982 mm , cell : 24 , Voc : 14.5v , Vmp : 11.75v , Isc : xxxA Imp: 6.38A 

The ratings for the panels still do not look correct (the 75 watt panels especially). Anyway, your array would have:

• Vmp-array = 23.5 volts * 9 panels in series = 211.5 volts nominal (standard temperature)
  
• Voc-array = 28.7 volts * 9 panels in series = 258.3 volts (standard temperature)
• Imp-array = 6.38 Amps * 2 parallel strings = 12.76 amps nominal

So--You already exceed the 11 amp max input current--It would then appear that this array will give you a maximum array wattage of:

• 211.5 volts * 11 amps max input current = 2,321 Watt DC array (standard test conditions)
• 2,321 Watts * 0.77 panel and controller deratings = 1,787 Watt AC output (typical peak in warm/sunny weather)
  

If your GT inverter is capable of higher wattage (and it manages the 11 amp "clipping" of array current), you could can put 3x 75 Watt panels in series with the 9x 150 Watt panels (~317.25 Vmp-array with 9+3 panels in series). That would give more solar power to the GT inverter (if it is capable of the larger/higher Wattage array).

• 317.25 volts Vmp-array * 11 Amps * 0.77 panel+controller derating = 2,687 typical peak output
  

-Bill

BB. said:

Jaymin,

Oops... Made a calculator error (did the 3x on the added panels twice)--Fixed original post in bold.

-Bill

BB. said:

Jaymin,

First, your GT inverter has an 11 Amp maximum input current (vs the ~2x 7.02 amps of each strings Imp). so you lost ~3 amps there.

And next Vmp is temperature dependent. Solar panels are typically rated under mfg. test conditions (flash testing--"full sun" for a few seconds "sun" lamp, cell temperature ~25C). In real life, solar panels get hot in full sun and Vmp fall--Roughly to ~81% of "std" Vmp on a nice spring day (very hot weather, Vmp can fall more. In very cold climates, below freezing, Vmp can be higher than STD test condition rating).

lastly, roughly 95% efficiency of the GT inverter...

• Total "derating" 0.81 panel temp * 0.95 GT inverter efficiency = 0.77 = 77% "typical power output" of "panel STD Rating (typical maximum on average spring day at noon time).

Does this make sense (It is midnight here--I may not be making much sense right now).

-Bill