200kW Off-Grid Solar PV System Design -1 hour Battery Backup - Hybrid

Project Requirements:

• Total load = 200kW
• Battery backup time = 1 hour
• Primary source = Solar PV
• Secondary source = Grid
• Tertiary source = Battery Bank

System Design:

1. Solar Panels:

Wattage of single panel = 235Wp

No. of solar panels = (Total load x 1.4) / 235

                                = (200,000 x 1.4) / 235
                                = 1192 (rounded value)
     2.  Inverters:
Company = SMA
Two types of inverters (built in charge controllers) will be used.
a). Sunny Tripower     b). Sunny Island (Grid Inverter Or Battery Inverter)

a) Sunny Tripower:
Requirement for sunny tripower = 280,000W*
* 200,000W x 1.4 = 280,000Wp
Suitable sunny tripower (according to the requirement) = STP 20,000 TL
No. of sunny tripower used = 14 

STP 20,000 TL

b). Sunny Island

Requirement for sunny island = 200,000W*
* Sunny island runs the load, so its rating depends upon total load. 

Key functions of Sunny Island:

• In case public grid goes down then Sunny Island generates its own grid and do not let your system go down. 
• In order to keep the Sunny Island running, a battery bank is a must.

Suitable sunny island (according to the requirement) = SI 5048
No. of Sunny Islands = 36*
*One can connect maximum of 36 sunny islands in one system. 36 sunny islands can support 300,000 W load for 1 minute (With suitable battery bank)
230,000 W load for half an hour (With suitable battery bank)
200,000 W load for 1 hour (With suitable battery bank)

SI 5048

Below design is in process    

 3. Solar PV array design:
According to the data sheet of STP 20,000 TL, the input DC voltage capacity of STP 20,000 TL is 750V. It has four inputs of solar PV arrays. The input voltage of one array must not be greater than 90 % of 750V. 
Since the open circuit voltage of one solar PV panel is around 34V. Connecting 15 solar panels in series will give us (15*34) 510V DC which is smaller than 675V (90% of 750V).
So we can make two solar PV arrays, having 15 panels each. All the 15 solar panels will be connected in series in one array.

     4. Battery Bank:
Battery rating is defined in terms of Ampere Hours (Ah). We can find out the Ah for battery bank according to the load and backup time.
Ah = (Load x backup time) / (DOD x PF x System Voltage)
Now
   load = 5000
   backup time = 1 hour
   DOD (depth of discharge) = 0.6
   PF (power factor) = 0.8
   System voltage = 48V
So
Ah = (5000 x 1) / (0.6 x 0.8 x 48)
      =  217.01
So now we need 217Ah @ 48V for battery bank.
Rating of single battery = 200Ah @ 12 V
Connecting four batteries of above rating, in series, will give us 200Ah @ 48V.

System Topology:

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