Developing Solutions for the Environmental Challenges to Deploying PV Plants in Desert Areas
Zia Malik
Technology Application and Advancement Group (TAAG) , Economic Development
King Abdullah University of Science and Technology, Saudi Arabia
Emirates Solar Industry Association, Dubai 2013
Main Environmental Challenges
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• Encapsulation and packaging • External cooling (Phase change material) Temperature
• Dry type cleaning • Wet type cleaning • Surface coatings
Dust
• Encapsulation and packaging Humidity
Temperature: Impact on different PV technologies
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Technology Manufacturing Costs
Commercial Efficiency
Theoretical Efficiency
Temperature Coeff.
Mono c-Si >90¢/Wp ~18% ~25% -0.38%/°C Multi c-Si >75¢/Wp ~14.5% <25% -0.45%/°C CIGS thin film
>80¢/Wp ??? ~12.2% <30% -0.31%/°C
CdTe thin film
<60¢/Wp 12.8% <30% -0.25%/°C
Source: First Solar
Temperature: KAUST experience
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Temperature: 2 MWp roof-top at KAUST
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Temperature: Performance of 2 MW Roof top at KAUST
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Temperature: Performance of 2 MW Roof top at KAUST
10%
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18%
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Ene
rgy Co
nversion
Efficien
cy
Daily Maximum Module Temperature oC
Eu = Generated Energy / Incident Irradia>on Energy (%)
Module Temperature Effect on Efficiency
Linear Eu
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Temperature: Performance of 2 MW Roof top at KAUST
• Annual yield simulated 1676+1605= 3,281 MWh/year
• Simulated energy yield from 01 May 10 to 01 March 11:
• 1,372 MWh + 1,312 MWh = 2,684 MWh
• Actual energy yield
• 1,399 MWh + 1,410 MWh = 2,809 MWh
• Increase in actual yield above plan = 126 MWh = 4.7%
PV module thermal management Needed for hot climates to improve performance and reduce aging
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Ambie
nt Te
mpera
ture (°
C)
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Energ
y Gen
erated
(kW
h)
Standard ModuleUtility Module
!
* ½ cell design “…. Reduced losses” * Modified EVA “…. improved thermal encapsulation”
Dust: Revise your O&M clacs
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• The drop in solar energy efficiency over 3 months without cleaning was measured between 30-45%.
• The decrease in solar energy efficiency due to dust storms was measured to be 60%.
• Dust effect on performance varies per location and per technology
• Needed models for recommended frequency of cleaning
Dust: Dust Mitigation Initiative
• 1st Understand & quantify the impact of soiling on region-specific solar technology performance.
• 2nd Evaluate & develop different dust mitigation solutions to reduce cleaning frequency for both existing & emerging technologies.
• 3rd Develop an optimum site & technology-specific cleaning schedule based on various cleaning methods.
• 4th Develop a dust prediction model for the Kingdom of Saudi Arabia.
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Coating Performance
Technology Maturity
Environmental Durability
Economics Reliability
O&M
Field Application
Dust Effect on Performance
Cleaning Dry
Passive Coatings
Hydrophobic
Hydrophilic
Anti-Static Active
EDS
Rotary Brush Wet
Dust: Dust Mitigation Initiative
Dust: Coatings potential
• Ideal coating would have mechanical and optical characteristics
• Coating life is at best 3 to 5 years and site specific
• Multiple re application of coatings can degrade performance
• Standards needed for coatings on PV panels
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Dust: Electrostatic Discharge Screens
• Ionizes dust particles using electric pulses
• R&D needed in polymer based EDS and ionization process
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Dust: Dry type brush based cleaning
• Dry-type cleaning/dusting robot for PV panels
• Using minimal amounts of water for cleaning PV panels
• Aimed for high reliability long life operation with minimal maintenance
• Automated robotic device
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Dust: Simple solutions are possible
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• Direct-light behavior of different soiling levels
Spectral Analysis & Effects on Transmission
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Rel
ativ
e G
lass
Tra
nsm
issi
on
Wavelength (nm)
Effect of Dust on Glass Transmission
Week 1
Week 2
Week 3
Week 4
Dust: Performance impact on PV
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• 60-day duration of panel exposure to dust • Particle Size Distribution • Information to be extracted:
• Most common particle size • Total number of particles (particle/m2) • Estimation of area blockage (%)
Dust: Performance impact on PV
Dust: Performance impact on PV
• Irregular particle shapes
• Particle-to-surface interaction and particle charge upon contact
• Detailed study on local dust characteristics
• Dust deposition rate on solar surfaces is approximately 12.5g/cm2/month in Thuwal Saudi Arabia.
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Cleaning OPEX for 2 MW Roof top at KAUST
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· Total system cleaning duration/week is 15 hours/week at approximately 3 hours of cleaning/day · Detergent usage is biweekly (5L of glass cleaner/month) amounts to SR100/month · Water flow rate is ca 1 m3/hr at SR6/m3 cost of water · 4 workers/day at SR3,000/month/worker · Project manager wage is 4,000/month · Total wages amount to SR16,000/month · Total monthly material amounts to SR550/month Total monthly cost to clean 2MW solar rooftop panels at KAUST is ca SR16,550/month
About 53,000 $US per year for cleaning only
• The drop in system efficiency has been measured to be 8 - 15% per month due to dust accumulation;
• Dust deposition rate on solar surfaces is approximately 12.5g/cm2/
month;
• Dust deposition rate at ground level & building rooftops prove to be identical;
• Need to include MENA environmental conditions in existing standards;
• There are solutions to dust that are practical;
• PV module manufacturers need to consider a “desert” module.
Summary
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