Days of Autonomy question

palausystem

Our installer says he gave us 2 days of autonomy.
48V system, there are 16 Rolls s-530 batteries ( 2 strings) with a capacity of 800 Ah (at what I believe is the C-20 rate?) He says we can use 5.9 KWh per day for 2 days before the generator kicks in.
This sounds a little optimistic, but I'm trying to figure out how close his estimate is or isn't.
Reading another thread, someone suggested a very rough (I think pre-effeciency conversions) equation of 1Kwh = 21 Ah for the 48V system. That would give a total of 19Kwh for the 400 Ah (50% dod)
Figuring a 100% state of charge, and a dod down to 50%, can someone tell me what my ballpark might actually be?
Thanks

Sunny Boy
Sunny Island 5048U
18 Sharp 170w
16 Rolls Surette S-530 48V

Cariboocoot

Re: Days of Autonomy question

800 Amp hours taken to 50% DOD = 400 Amp hours * 48 Volts = 19,200 kW hours DC, about 17 kW hours AC.
That's near 3 days at 5.9 kW hours per day by my reckoning.

icarus

Re: Days of Autonomy question

I think 'Coot has it dialied. Personally I would look towards a 25% DoD for longer battery life, but that is a different financial calc.

You might like to read the following and ,,, welcome to the forum,,,

Tony

http://www.batteryfaq.org/

http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries