SIZING OF SOLAR PV SYSTEMS FOR OFFICE LIGHTING APPLICATIONS

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SIZING OF SOLAR PV SYSTEMS FOR OFFICE LIGHTING
APPLICATIONS
Authors Rajashekar P. Mandi Udaykumar R.
Yaragatti
280 W solar PV plant is installed at CPRI

• PRESENTER
• Arun Kumar Datta.
• Central Power Research Institute, Bhopal.

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Solar PV System
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Solar radiation
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Solar radiation
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Ambient Temperature
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PV Cell Temperature
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PV Cell Temperature
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Ambient Temperature
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PV Cell Efficiency
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PV Cell Efficiency
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Load pattern
Sl. No. Type of load Power, W Quantity, Nos. Total power, W
01 40 W twin mirror optic FL 108 2 216
Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 22
Total power required Total power required Total power required Total power required 238
Daily average energy required (_at_ 6 hours of operation) 1.43 kWh/day Daily average energy required (_at_ 6 hours of operation) 1.43 kWh/day Daily average energy required (_at_ 6 hours of operation) 1.43 kWh/day Daily average energy required (_at_ 6 hours of operation) 1.43 kWh/day Daily average energy required (_at_ 6 hours of operation) 1.43 kWh/day
Sl. No. Type of load Power, W Quantity, Nos. Total power, W
01 20 W 4 LED lamps 20 4 80
Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 Design margin for transients, etc _at_ 10 8
Total power required Total power required Total power required Total power required 88
Daily average energy required (_at_ 6 hours of operation) 0.53 kWh/day Daily average energy required (_at_ 6 hours of operation) 0.53 kWh/day Daily average energy required (_at_ 6 hours of operation) 0.53 kWh/day Daily average energy required (_at_ 6 hours of operation) 0.53 kWh/day Daily average energy required (_at_ 6 hours of operation) 0.53 kWh/day
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System sizing
Sl. No. Variable Unit Value
01 Overall cell efficiency (max.) _at_solar radiation of 1000 W/m2 at 25 oC 13
02 Fill factor of solar PV panel 80
03 Overall module efficiency 10.4
04 Inverter efficiency 90
05 Circuitry loss 1
06 Overall SPV to AC load efficiency 9.27
07 Battery charger efficiency 85
08 Depth of discharge of battery banks 40

• Base solar photovoltaic panels other
  accessories Rs. 1,80,000 per kW
• (without inverter battery storage)
• Grid inverter power system (without battery
  banks) Rs. 39,000 per kW
• Battery size including charge controller for 1
  hour autonomy Rs. 13,500 per kWh

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Configuration
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Techno-economics for Scheme 1 4.366 kWh/m2-day
(during the month of July)
Total Energy (TFL) 521 kWh/y Total Energy (LED)
193 kWh/y
Sl. No. Particulars For TFL For LED
01 Energy generated by solar PV 347 kWh/year 154 kWh/year
02 Energy from grid 174 kWh/year 39 kWh/year
03 Share of energy import from grid 33.4 of total energy 20.2 of total energy
04 Cost for solar PV system including battery for storage, inverter and controller Rs. 65,000 Rs. 32,000
05 Cost for LED lamps - Rs. 12,000
06 Total Cost Rs. 65,000 Rs. 44,000
07 Payback period 21 years 15 years
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Techno-economics for Scheme 2 6.739 kWh/m2-day
(during the month of March)
Total Energy (TFL) 521 kWh/y Total Energy (LED)
193 kWh/y
Sl. No. Particulars For TFL For LED
01 Energy generated by solar PV 694 kWh/year 308 kWh/year
02 Excess energy generation by SPV 173 kWh/year 115 kWh/year
03 Solar PV energy share 100 of total energy 100 of total energy
03 Cost for solar PV system including battery for storage, inverter and controller Rs. 1,10,000 Rs. 55,000
04 Cost for LED lamps - Rs. 12,000
05 Total Cost Rs. 1,10,000 Rs. 67,000
07 Payback period 35 years 22 years
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Techno-economics for Scheme 3 5.171 kWh/m2-day
Total Energy (TFL) 521 kWh/y Total
Energy (LED) 193 kWh/y
Sl. No. Particulars For TFL For LED
01 Energy generated by solar PV 462 kWh/year 182 kWh/year
02 Excess energy generation by SPV (Jan. June) 8 kWh/year 8.7 kWh/year
03 Energy requirement from grid (July Dec.) 67 kWh/year (12.8 of total energy) 17.5 kWh/year (9.2 of total energy)
04 Min. monthly energy generation (July) 31.8 kWh/month 12.3 kWh/month
05 Max. monthly energy generation (March) 47.6 kWh/month 18.4 kWh/month
06 Inverter rating (min.) 250 VA 100 VA
07 Battery charger rating (min.) 250 VA 100 VA
08 Battery capacity required (12V DC bus) 180 Ah 100 Ah
09 Total SPV system Cost Rs. 54,000 Rs. 24,000
10 Cost for LED lamps - Rs. 12,000
11 Total cost Rs. 54,000 Rs. 36,000
12 Payback period 17 years 10 years
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INTEGRATION I
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SCHEME III TFL
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SCHEME III LED
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SCHEME III LED
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Solar PV sizing
Sl. No. Particulars Specifications for TFL Specifications for LED lamps
01 Total PV array capacity 280 W 140 W
02 Capacity of individual array 70 W 70 W
03 Total No. of panels 4 Nos. 2 Nos.
04 Tilt of the panel 22o south 22o south
05 Rated voltage of each panel 12 V DC 12 V DC
06 Open circuit voltage of each panel (VOC) 14.7 V DC (min) 14.7 V DC (min)
07 Short circuit current of each panel (ISC) 6.2 A 6.2 A
08 Temperature coefficient of ISC 0.065?0.015 / oC 0.065?0.015 / oC
09 Temperature coefficient of power -(0.5?0.015) / oC -(0.5?0.015) / oC
10 Weight of each panel 12 kgs or less 12 kgs or less
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Battery Bank sizing
Sl. No. Particulars For TFL For LED
01 Daily energy (apparent energy) required 180 VAh 100 VAh
02 Battery voltage 12 V 12 V
03 Capacity of each battery 180 Ah 90 Ah
04 Charging discharging cycle efficiency 85 85
05 Depth of discharge of battery bank 40 40
06 Actual No. of battery banks required 1 No. 1 No.
07 No. of hours of autonomy 6 hours 6 hours
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Results
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Results

• Energy estimated (Solar PV) 454 kWh/y (87.1 )
• Energy estimated (Grid) 67 kWh/y (12.9 )
• Energy generated by solar PV 403.7 kWh/y (92.25
  )
• Energy import from grid 33.9 kWh/y (7.75 )

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CONCLUSIONS

• Sizing of solar PV system with lowest monthly
  average daily solar radiation requires smaller
  size of PV but higher dependence on grid power.
• Sizing of solar PV system with highest monthly
  average daily solar radiation requires higher
  size of PV but lower dependence on grid power and
  the overall cost will be high.
• Optimum sizing of solar PV system will reduce the
  overall cost and project become more attractive.
• Use of LED lamps for the office buildings reduce
  the specific size of solar PV system for the
  given illumination level output.
• Installation of solar PV system with LED lighting
  system will be economically viable.

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Thank you
CPRI
Arun Kumar Datta. CPRI, Bhopal.
emailrajashekarmandi_at_yahoo.com mandi_at_cpri.in