optimal design of a standalone photovoltaic power supply ... · • data source: – nasa surface...
TRANSCRIPT
Getachew Bekele (PhD) Addis Ababa Institute of Technology
Optimal Design of A Standalone
Photovoltaic Power Supply System for Air
Conditioning Application at Samara
University in Ethiopia as an Alternative to
Diesel Generator
AAiT, Elect. & Comp. Engineering Dept, Addis Ababa, Ethiopia 2
Locations
11.45 °N, 41E
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Background
• Annual temperature: 27C - over 50C
• Self-contained diesel station supplies electricity; the utility
grid is not yet within reach
• Animosity of diesel fuel and environment
• Increasing fuel price
• Requires skilled personnel for O&M
On the other side:
• Falling price of PV module
• Improvement of its PV efficiency
AAiT, Elect. & Comp. Engineering Dept, Addis Ababa, Ethiopia 5
Solar energy potential
• Annual average solar radiation for Ethiopia is 5.26 kWh/m2
• Afar region reaches up to 6.10 kWh/m2
• Data source:
– NASA Surface meteorology recorded for more than 10 years
– Also from Solar Energy: RETScreen Data
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Thermal load
• The load is air conditioning unit
• The estimation is done based on a popular and widely used thumb
rule for load estimation developed by company based designers
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Electrical load ... (Cont’d)
• The electrical load of the PV is selected to be an evaporative
air conditioning (EAC) unit through comparison against
refrigerated air conditioning (RAC)
Cooling load and electric consumption Average initial expense
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Standalone PV System
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Components
• Energy consumption of the units is calculated as 2,140 kWh/day
(kW × hours /day)
• 15% noise level has been added to the calculated load
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Input to HOMER
PV Diesel Generator Battery (Surrette
6CS25P)
Converter
Size (kW) 1 1 1,156Ah 1
Capital ($) 3,480 288 644 700
Replacement cost ($) 3,480 210 483 700
O&M cost ($/yr) 0 0.025($/hr) 20 0
Sizes considered
(kW)
0, 100, 520,
530, 540, 550,
600
0, 200, 292, 380 0, 100, 150, 200,
250, 300, 350,
400
Quantities considered 0, 80, 140, 150,
160, 180
Life time 25 years 60,000hrs 9,645 kWh 15 years
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Result &discussion
PV
(KW)
Gen
(KW) Battery
Inverter
(KW)
Capital cost
($) NTC ($)
COE
($/KWh)
Renewable
Fraction
Diesel
($/yr)
Gen
hours
(hr/yr)
540 - 1,200 250 2,827,000 3,666,051 0.323 1 - -
520 - 1,280 250 2,808,920 3,698,888 0.326 1 - -
550 380 1,200 300 3,006,240 4,200,306 0.345 0.94 24,538 393
600 380 1,280 300 3,231,760 4,283,414 0.352 0.97 11,695 189
600 380 1,440 300 3,334,800 4,411,491 0.363 0.98 6,592 108
100 380 - 100 527,440 5,849,272 0.481 - 356,649 5,227
100 380 - 150 562,440 5,899,329 0.485 - 356,649 5,227
- 380 640 100 591,600 6,513,526 0.536 - 369,070 5,447
- 380 640 150 626,600 6,562,532 0.54 - 369,013 5,445
520 380 - 200 2,059,040 6,907,650 0.568 0.1 321,626 4,844
520 380 - 250 2,094,040 6,933,183 0.57 0.11 320,035 4,817
- 380 - - 109,440 6,968,115 0.573 - 460,330 6,830
Overall optimization results
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Catagorized optimization results
Result &discussion ... (Cont’d)
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Result &discussion ... (Cont’d)
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Cost summary
Result &discussion ... (Cont’d)
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Result &discussion ... (Cont’d)
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Conclusions
• The study indicated that with 5.58–6.66 kWh/m2 potential, the
region is a prospective candidate for deployment of PV systems.
• In this work evaporative air conditioning system is proven to be a
more efficient load for the PV system
• The cost of energy (COE) is obtained is 0.323 US$/kWh for a
diesel fuel price of 0.8$/l,
• The maximum capacity shortage is just 10%.
• Hence, a stand alone PV system with battery storage (100%
renewable resource) is the preferable solution to the diesel
• The finding here is applicable to many similar
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