Solar power System Design

There are many types of solar power packs depends on there power ratings like: 
- 200 W (day pack)
 - 200 W (day+night)
 - 200 W ( night pack)
 - 500 W (day pack)
 - 500 W (day+night)
 - 500 W (night pack)
 - 1 KW (day pack)
 - 1 KW (day+night)
 - 1 KW (night pack)
 - 2 KW (day pack)
 - 2 KW (day+night)
 - 2 KW (night pack)...............................................................
 
Electrical units(KWh) to be save per day:
any solar power system can save maximum units per day four times of there power rating in KW like:
1 KW solar power system can save Maximum units per day = 4*1 KW
                                                                                            =4 units/day
Designing of solar power pack:
- 200 W (day pack):
 
 It can save maximum  0.2*4 = 0.8 units /day
and it can work properly only in day light because in this system we will using battery backup only for a small time.