Design a PV system for the following application A refrigera

Design a PV system for the following application:

A refrigerator/freezer unit for vaccine storage in a remote island of Roatan, Honduras (16°N Lat., 86°W long., Temp. range 15-30°C) assuming a year-round average insolation on a horizontal surface of 7 kWh/m2-day. Two compressors: one each for refrigerator and freezer. Each compressor draws 5 amps @ 12 V. Compressors remain on for Summer Winter Refrigerator 9 hrs/day 5 hrs/day Freezer 7 hrs/day 4 hrs/day The available module has rated voltage of 17.2 V at 25°C (15V @ 55°C) and 2.3 amps @ 1 KW/m2. The available battery has a rated capacity of 110 Ah at 12 V. Assume maximum depth of discharge 25 % .

Solution

solution:

1)here let design PV ssytem for two compressor

2)in given PV system should contain PV array as set of number of module,battery,inverter and load connected in parallel across suply,

hence voltage of load=V=12 v

current=I=i1+i2=5+5=10 amp

3)power required for given system is

P=V*I=120 j/s

4)here given battery can discharge only 25% of total capacity,hence

as per battery rating,battery will supply power with 12 v and 10 amp power for given capacity for 11 hrs but for 25% it is as follows

AH rating=current*time

110*.25=10*time

time=2.75 hrs

mean for given depth of discharge battery will work for 2.75 hrs.whatever discharge is occure we have to fill it by charging from PV system

4)hence total power require for 2.75 hr is as follows

Prequired=V*I*time=12*10*2.75*3600=1188000 j

5)where at 25 c PV module of m2 efficiency is

n=Vm*Im/I=17.2*2.3/1000=.03956=3.9656%

6)hence for insolation of 7KWH/m2 power output of single module is

power incident per hr=7000 watt/hr

hence power input per second=7000/3600=Pin=1.944 watt

where as per efficiency power output of single module is

n=Pout/Pin

Pout=.03956*1.944=.0769 watt

6)hence each module is producing .0769 watt,hence to produced this much amount of power in 2.75 hr,number of module required is

N=number of module=Prequired/Pout*t=1188000/2.75*3600*.0769=1560.46 module

7)hence given solar panel should have 1560.46 approximated to 1561 module per panel for efficient working of battery and compressor are required as per specified at 25 c