Adding more panels to existing Array and second controller.

Billy

I am getting ready to add more solar panels to my existing array of 2,135 Watts.
I have been given (8) Suniva OPT280-60-4-1B0 panels, with micro inverters, (which I will not use)
Vmp =31.9v and Imp=8.78a on each panel
I will add another controller to go with my outback flex 80 for those. Another combiner box to connect the panels.
Question is Will the total Watts of the 8 280-Watt panels be too much for the outback 80?
I plan on each two panels connect in series then run four to my box.

BB.

Still 24 VDC battery bank?

The typical "optimum" max power would be:

• 29.0 volts charging * 80 amps * 0/0.77 panel+controller deratings = 3,013 Watt array maximum suggested "optimum"

The spec sheet talks about 2,000 Watts max @ 24 volts

https://www.solar-electric.com/lib/wind-sun/Outback_FM60_FM80_Specifications.pdf

Page 100 of the manual does not say much more about array design (other than Voc-cold):

https://www.solar-electric.com/lib/wind-sun/Flexmax-manual.pdf

In general, good quality MPPT controllers limit their output current to max rated (and derate as controller runs hot)... 

You also need to check Voc-array-cold for your location--From the Outback manual and guessing you are in Texas, and that it does not get much below freezing in your area:

Cooler climates can cause the Voc to rise above the array’s rated Voc. In climates that observe temperatures less than about –15°C (5°F), a Voc greater than 125 Vdc is not recommended.

o Hot weather: lower Voc and lower Vmp o Cold weather: higher Voc and higher Vmp If the specific voltage temperature correction factor is not known for a particular module, allow for ambient temperature correction using the following information:

25° to 10°C (77° to 50°F) multiply Voc by 1.06
9° to 0°C (49° to 32°F) multiply Voc by 1.10
–1° to –10°C (31° to 14°F) multiply Voc by 1.13
–11° to –20°C (13° to –4°F) multiply Voc by 1.17
–21° to –40°C (–5° to –40°F) multiply Voc by 1.25 1

145 Volts is max "starting voltage":

• 145 VDC max operational / 1.13 derate = 128 VDC Voc-std array voltage

https://energypal.com/best-solar-panels-for-homes/suniva/opt280-60-4-1b0

Voc-std ~ 39.2 VDC

• 128 VDC temp corrected Voc-array-max / 39.2 VDC panel-std = 3.3 panels in series = 3 panels in series max

2 panels in series is fine for a 24 volt battery bank...If you plan on going to 48 volts someday, then 3x panels in series is required for proper/optimum charging. 2x panels in series is too low for charging a 48 VDC battery bank (upwards of 60 VDC required + voltage drop + "hot panels" Vmp-array deratings--Usually suggest Vmp-array-std of ~70 VDC minimum).

-Bill

Billy

Yes Bill, 24 volt system and gulf coast Texas ,Sugar Valley area close to Van Vleck Texas.

Billy

If total 2240 Watts is too much for outback, would the Midnite solar 150 charger work and still be able to charge the same battery bank along with the Outback?

BB.

I don't think it is too much for the Outback... But I am not the expert here. "Over paneling" by 1/0.77 or 1/0.75 (1.33x) is normal.

Perhaps others here can confirm.

-Bill

littleharbor2

Midnite classic 150 will output 2700 watts @ 24 v0lts nominal.

Dave Angelini

If your inverter/charger is an outback you should stay with them for the whole system so they can be networked.
If this is Offgrid you will not be heat stressing equipment like a grid tie, I would not worry about 2240W nameplate for an 80 A controller.
Good Luck!