Battery Sizing.xmcd
A Cabin near Salt Lake City, Utah, has an AC energy demand of 3 kWh per day in the winter months.
(Q) Calculate the size of the battery system.
kWh / day
Inverter Efficiency
Battery System Voltage
SOLUTION
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1. DC energy demand (Edc):
kWh /day
2.
Expression of the energy demand in terms
of Amp-Hour per day.
Energy=Power*Time = V*A*time,
==> A*hour = Wh/V
Ah/day
3. Find the usable storage Ah at -10 C degree
a. Peak-Sun-Hour information
b. Find the # of days of usuable storage(Dus) on the 95% availability curve
From the curve, we find for Dus:
days
c. Now we calculate the Usuable Storage Amp-Hour (AHus)
Ah
d. Finally, the nominal (C/20, 25 C) capacity:
Ah
With Dus=4.6 (~ 5 ) days = 72 hours,C/72 Rate, at -10 C, the value is 0.97.