drich5

Assuming you have the battery bank wiring and proper AGM batteries figured out:

http://www.smartgauge.co.uk/batt_con.html

Along with breakers/fuses for the bank--Designing for the battery bank capacity (solar array sizing):

• 8 * 155 AH * 14.4 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 1,159 Watt array minimum
  
• 8 * 155 AH * 14.4 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 2,319 Watt array nominal
  
• 8 * 155 AH * 14.4 volts charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 3,015 Watt array "cost effective" maximum

So--1,200 Watts of panels does meet the minimum recommended 5% rate of charge. The minimum size of MPPT charge controller would be:

• 1,200 Watts * 0.77 panel+controller derating * 1/14.4 volts charging = 64 amp minimum recommended charge controller
  

You will not damage your MPPT MorningStar charge controller at 60 amps--You will just have a bit more current limited output (normal MPPT controller operation) on cold/clear days.

Typically, the optimum Vmp-array rating is ~2x battery charging voltage--So, placing your panels in 2x series * 4 parallel would be the typical answer.

If, you have a long wire run from the array to the battery bank+charge controller, you could also go with 4x series * 2x parallel (Vmp-array~72 volts Vmp). The charge controller will be a little less efficient with the higher Vmp-array voltage.

Note, with a large battery bank and array--A 1,240 AH @ 12 volt battery bank will require pretty large wiring (for low voltage drop)--It also limits you to ~1,200 Watts on a 60 Amp MPPT MorningStar controller.

If you where to do a 24 volt battery bank, then you could run almost 2,400 Watts on the 60 Amp controller (620 AH @ 12 volt battery bank) and install more panels later with the same charge controller.

Anyway--That is the basics.

-Bill

Roughly, the "most efficient" Vpanel working voltage is ~2x the battery voltage. So, charging at ~15 volts would be Vmp-array~30 volts.

If you run at a higher working voltage (not sure in the MorningStar case, but as I remember, Vmp-array~100 VDC would be the rough maximum for colder climates with Voc~140-150 VDC max for the controller input), then the controller is a bit less efficient.

See page 34 (file page #) of a TS 60 MPPT controller:

http://www.morningstarcorp.com/wp-content/uploads/2014/02/150V-TS-MPPT-Operators-Manual.pdf

The lost efficiency is just about a "don't care" in overall system electrical design (I.e., 97% vs 93% eff)--However, from a hardware point of view, that is 2x more heat for the electronics to dissipate (between Vmp~18 volts vs Vmp~96 volts). Hot electronics (and thermal cycling) are killers (shorten equipment life).

-Bill