New to solar.

[mesabob]

Need to change solar system.I am off grid completely.I currently have outback mate3 system with flexware industrial control panel to 2 vfx33648 another flexware then 2 flex80 150vdc.Trace DC disconnect fir batteries.The batteries are agm 2volt 915ah 24 total.Panel total 4800 watts.Not enough power generation.System is 2014 dated.I run 3 LG 1.5ton mini splits 10hrs a day.I'm thinking 5 10kwh battery banks and 7200 watts of panels.I live on a 14000 acre mesa at 6800 ft .Sun hours are 6.7 average.Am I thinking in the right direction?.Thank you for your suggestions

 

[MichaelK]

Not a big fan of AGM batteries, but you have to work with what you've got. Some AGMs like charging rates up to 0.2C, though for standard lead-acid, it's more like 0.125C.

Running the numbers for your 915Ah battery bank it looks like 915Ah X 0.2C = 183A. Even at LA charging levels, that's 114A. Assuming you de-rate your panels to 85%, and you are bulk charging at as low as 50V, then what you are actually getting is (4800W/50V) X 0.85 = 81.6A. So, yes, you need more solar.

Working in the opposite direction, assuming that each controller can handle a max of 80A, then what you should have is (80A X 50V)/0.85 = 4705W of panels PER CONTROLLER. Since you have two controllers, you could double your watts today without any issues.

So, the quick answer is no, don't upgrade to just 7200W. Upgrade all the way up to 9600W.

I'm not a big fan of parallel strings of batteries either. I'd look at a single string of 1000Ah batteries to get the amount of power you want. Here's is a high-end battery that I think would serve you well. Twelve of these to make a 48V bank.

4 KS 21P | Rolls Battery

www.rollsbattery.com