Solar Power based Backup System

Almost all the households of the country face problem of electricity-cuts or load shedding.  A conventional way solving this is using Invertors with battery back-up. However, a non-conventional and upcoming method has been using Solar Energy. The equipment required for a basic Manually-Operated Solar Back-up system are:
  • Solar Panels
  • Solar Charge Controller
  • Battery pack
  • DC to AC Inverter
  • Wiring & Sockets
  • Panel Stand
  • Battery Rack

Now, we look at functions of each of the following equipments:

Equipment Function
Solar Panel Generate DC when Sunlight falls on them
Solar Charge Controller Charges battery and prevents reverse current in case of voltage drop.
Battery Stores Electricity DC current (as chemical energy)
DC to AC Inverter Converts DC current from batteries to AC Current
Panel Stand Mounts Solar Panel safely
Battery Rack Keeps battery safe
The 3rd step is the connection diagram:
Arrangement of Equipment for Solar power backup
Arrangement of Equipment for Solar power backup
With Equipment and arrangement being clear, the next step is estimation of House load and based upon that System capacity. For sake of comparison, let us make a list of equipments that are to be placed on Inverter back-up in a 3BHK flat.
Equipment Number Watts Total
Tube Lights 3 40 120
Fans 3 80 240
Refrigerator 1 100 100
Computer 1 120 120
Misc. 1 70 70
Total     650
Hence, the load of equipment in our case = 650 watts.

Lets say we need backup for 1 hr.
Now going in reverse order:

  • Capacity of DC-AC Inverter = 650/0.8 (safety factor) = 800watt
  • Battery Capacity = power to be delivered * time = 650* 1
    • Considering each battery = 12 V & number of battery = 2
    • 650 = 2*12*AH
    • AH = 650/48 = 27
    • Hence, we need to buy 2 batteries of 12 V and 27AH each
  • Solar panel, needs to produce 650 watts of power on average in a day (5 hrs,0.8 efficiency factor) .
    • Panel wattage = 650/ (5*.8) = 162.5 watt
    • Thus 200 watt solar panel that produces dc electricity at 12V, would suffice.
This brings us to last and most important part. i.e. cost of the system
Equipment  Cost Per unit  Total Cost
Solar Panel 6000/100 Watt 12000
Solar Panel Stands 5000 5000
Solar Charge Controller 3500 3500
Solar Invertor 3000 3000
Batteries 5000/unit 10000
Wiring 2000 2000
Total System Cost 35500
Thus complete system would cost 35000 INR