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Space Research Institute 8th International Energy Conversion Engineering Conference
S PA CE
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Space Research Institute 8th International Energy Conversion Engineering Conference
Comparison of Photovoltaic Modeling Analysis and Actual Performance - - PowerPoint PPT Presentation
Comparison of Photovoltaic Modeling Analysis and Actual Performance - - PowerPoint PPT Presentation
S PA CE R ESEA RCH I N ST IT U T E Comparison of Photovoltaic Modeling Analysis and Actual Performance Data of Lee County Justice Center Solar Power Installation Project Julie A. Rodiek and Steve R. Best Space Research Institute, Auburn
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Space Research Institute 8th International Energy Conversion Engineering Conference
Project Overview
Lee County’s TK Davis Justice Center (LCJC) awarded grant from
Alabama Department of Economic and Community Affairs (ADECA) to install an expandable system of photovoltaic solar panels
» Initial installation consists of a 16.6 kW grid-connected PV system » Will offset some of the energy costs of electricity used by the LCJC Auburn University working with LCJC to determine the optimal
photovoltaic system
» Site and system limitations » Installation planning/oversight » Performance Analysis » Monitoring and assessment
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Space Research Institute 8th International Energy Conversion Engineering Conference
Objectives of Project
Compare actual power performance to modeled predictions »
Determine reasons behind variations between programs
Monitor the performance of this system along with weather and
environmental factors
Information gathered through the system’s design, installation, and
monitoring will provide valuable information concerning photovoltaic alternative energy systems on public facilities
»
Use as a prototype for other similar undertakings
»
Used different mounting options and tilt angles
Excellent teaching and demonstration tool Showcase for potential solar installations at other facilities Establish a message that local governments need to take an active role in
increasing energy-efficiency and environmental sensitive building designs while reducing operational costs for its citizens over the long-term
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Space Research Institute 8th International Energy Conversion Engineering Conference
Why Now…
Increasing energy costs Reduce the U.S. reliance on foreign oil and also the need for
new power plants fueled by coal or oil
Upsurge has taken place in the use of cost-competitive
photovoltaic technologies for terrestrial applications
Existing 30% U.S. Government tax credit for installing
photovoltaic (PV) and/or solar hot water systems coupled with tax incentives in a few states
Why NOT now….electricity is cheap in Alabama, lack of
certified in-state installers, no state incentives
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Space Research Institute 8th International Energy Conversion Engineering Conference
What About Sunshine In AL?
Al has ~20% less
sunlight than the best in the SW
Plenty of sunshine
»
Power is produced on rainy day too
Al is better than
the NE, with major new installations now
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
Load Monitoring
Electronic load monitoring and data logging
- f some load center panels in the Central
Utility Plant of the LCJC were made
»
Help determine the load placed on PV arrays
»
Illustrates the hourly and daily variations in the electrical load demands of this one circuit
»
Continuous operation: 24hr / 7day
»
Peaks nominally during daylight hours matching the generation capability of the photovoltaic array very well
Used as input to a solar power modeling
program to project system performance, help
- ptimize design, and compare to predicted
performance
Electrical inverter specifications determined
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
PV Module Comparison
Study done of the types and performance of
photovoltaic modules that are currently available in the market
»
Comparison of PV modules ratio to highest power
»
Cost to power ratio was also calculated
When choosing the photovoltaic panels it is a
decision of efficiency versus cost
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 100 150 200 250 300 350 $/Watt Watts mc-Si Modules c-Si Modules 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 600 700 800 900 1000 1100 1200 1300 Watts/(Ft^2) Dollars mc-Si Modules C-Si Modules
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
CAD Model of LCJC Detention Center
Photo used to generate CAD model Building outlines & elevations
added
Roof equipment detail added as
needed
Google Earth & SketchUp used
» Aerial site photo imported into
Google SketchUp from Google Earth
» Geographical data conserved » DoE EnergyPlus plugin: OpenStudio
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
CAD Model of LCJC Detention Center
Room to install now
and/or expand in future
Some public visibility
is important to this installation
Large, mostly unobstructed
north/south-aligned flat roof
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
Shadow Study Analysis on Roof Mounts w/SketchUp
Winter Solstice Summer Solstice
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array System Analysis
PV Design Pro-G Modeling
Selected Inputs »
220 W SunPower Panels
»
480 V Solectria PVI-13kW Inverter
»
30-year weather profile database for Montgomery, Ala.
»
East – West tracking system
Fixed tilt of 30 degrees 35.5% of the annual load for specified circuit is produced by PV energy Annual total of energy provided to the load of 40,634 kWh All of the energy generated by the system cannot be used by this load »
Automatically shifts the excess power to another circuit so all the power generated by the array will be used within the facility
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Space Research Institute 8th International Energy Conversion Engineering Conference
Angle Study at Auburn University
Test the accuracy of solar modeling programs »
Discrepancy may be due to the way each program applies the angle tilt of the array thereby calculating solar irradiance to estimate the power production
There are six test panels »
Five panels rotated in a single axis at the tilt angles of 20º, 25º, 32º (latitude), 40º, and 50º
»
Another panel will be a control panel that is fixed facing south at latitude tilt
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Space Research Institute 8th International Energy Conversion Engineering Conference
LCJC PV Array Project Layout
System completion and certification, June 29, 2009
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Space Research Institute 8th International Energy Conversion Engineering Conference
Balance of the PV System
Inverters are used to convert solar array DC to
utility-quality AC
»
Roof Array: Solectria PVI-13kW 480 VAC, 3- phase
Inverter output from Solectria’s SolrenView site »
Pole Array: SunPower SPR3000m 3kW, 208 VAC
Inverter output from SMA’s SunnyPortal site »
SMA’s WebBox and SensorBox collect both roof and pole array environment data onto SMA’s SunnyPortal :
Solar irradiance Module temperature Ambient air temperature Wind speed Performance data are used to monitor system
and compare to model predictions
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Space Research Institute 8th International Energy Conversion Engineering Conference
System Modeling
PV Design Pro-G, PV Watts, and PVSYST used for analysis of system
»
Each program different
»
Some are more detailed on inputable parameters Highest power performance prediction
»
PVSYST for pole array
»
PV Design Pro G for roof array
PVSYST Design Pro G PV Watts PVSYST Design Pro G PV Watts Jan 1100 1203 1162 161 189 175 Feb 1156 1366 1288 163 201 182 Mar 1496 1805 1745 197 250 230 Apr 2132 2044 1982 265 263 243 May 2320 2160 1958 273 263 227 Jun 2264 2028 1887 261 240 213 Jul 2225 2063 1889 260 246 216 Aug 2245 2018 1797 273 252 216 Sep 1888 1817 1639 243 242 210 Oct 1803 1691 1615 252 245 224 Nov 1325 1290 1233 197 199 183 Dec 1220 1174 1082 188 190 165 Yearly Production 21,174 20,659 19,277 2732 2777 2484 Roof Array Pole Array
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Space Research Institute 8th International Energy Conversion Engineering Conference
LCJC Performance Year 1
(June 29, 2009 – June 30, 2010)
Total AC Energy provided to LCJC since commissioning, June 29, 2009 »
25,373 kWh
Has offset 18.2 metric tons (40,163 lbs) of CO2 emissions »
Equivalent to the amount produced by using 2,047 gallons of gasoline or 42.3 barrels of oil
»
The CO2 emissions from 1.5 homes for a year, or the carbon sequestered by 467 seedlings grown for 10 years, or 3.9 acres of pine or fir forests
Overall LCJC production tracks well with three solar modeling programs
LCJC Roof and Pole Solar Array Power in January
10 20 30 40 50 60 70 80 90
1 / 1 / 1 1 / 2 / 1 1 / 3 / 1 1 / 4 / 1 1 / 5 / 1 1 / 6 / 1 1 / 7 / 1 1 / 8 / 1 1 / 9 / 1 1 / 1 / 1 1 / 1 1 / 1 1 / 1 2 / 1 1 / 1 3 / 1 1 / 1 4 / 1 1 / 1 5 / 1 1 / 1 6 / 1 1 / 1 7 / 1 1 / 1 8 / 1 1 / 1 9 / 1 1 / 2 / 1
AC Energy (kWh)
Pole Array Roof Array
500 1000 1500 2000 2500 3000 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10 Feb-10 Mar-10 Apr-10 May-10 Jun-10 AC Energy (kWh)
LCJC Actual Performace Data Compared to Modeling Predictions
Actual Array Performance PVSYST Design Pro G PV Watts
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Space Research Institute 8th International Energy Conversion Engineering Conference
AC Power Produced July 12-18th
Week
demonstrates all different types of weather patterns
Power profiles
vary due to cloud cover and storm fronts
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Space Research Institute 8th International Energy Conversion Engineering Conference
Solar Array Power vs. Insolation
Linear relationship of
solar intensity and power for pole and roof array
Roof scatter due to
differences in how the data is acquired and averaged
»
Not temp.corrected
Efficiency of panels »
18% from data
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Space Research Institute 8th International Energy Conversion Engineering Conference
Insolation Data
Actual insolation data obtained by our sensors on the roof and pole
arrays have been compared to the modeled insolation for both PV Watts and Design Pro G
The two modeling programs use different insolation estimations The roof insolation is greater than expected
»
Currently looking into this
»
The arrays may be tilted at a different angle than anticipated
50 100 150 200 250 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Insolation (kWh/m2)
Insolation Data Pole Array
LCJC Pole Actual PV Watts Pole Design Pro G Pole 50 100 150 200 250 300 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Insolation (kWh/m2)
Insolation Data Roof Array
LCJC Roof Actual PV Watts Roof Design Pro G Roof
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Space Research Institute 8th International Energy Conversion Engineering Conference
Future Expansion
This initial system can serve as the backbone of an
expandable, renewable power system at this complex
Evaluating future expansion
sites
»
35 kW on roof
»
150 kW using low-profile ground mounts
Currently the facility is
installing a solar water heating system to further their mission to become more energy efficient
150 kW 35 kW
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Space Research Institute 8th International Energy Conversion Engineering Conference
Summary
This paper has used the data collected at the Lee County’s T.K.
Davis Justice Center 16.6 kW grid-connected solar-powered system and analyzed it to find trends and anomalies
Compared the performance data to the results of photovoltaic
modeling programs that were used before and during installation of the system
» The accuracy is quite good » Currently the system is producing about 5-7% more power for two detailed
modeling programs and 15% more than the more basic modeling program
Variations between program results appear to be based on how detailed the program is and how many variables used to better represent the system
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Space Research Institute 8th International Energy Conversion Engineering Conference
Lee County’s Example
Alabama’s first State Government sponsored PV energy project » Successfully completed on schedule and is fully operational It can serve as a model of how local governments can: » Be an example of how to increase energy-efficiency » Be environmentally friendly and reduce operational costs over the long-term This project’s unique location, ease of replication and expansion » Has the potential to be the prototype for other similar undertakings across the
State of Alabama
» Allows wide access to agencies, businesses, and individuals to inspire them » Excellent teaching and demonstration tool for all sectors Please visit our website at http://sri.auburn.edu/leecounty.htm or Lee
County’s website at http://www.leeco.us/solar_project/index.html
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Space Research Institute 8th International Energy Conversion Engineering Conference
Enthusiastic Press Coverage…
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ACKNOWLEDGEMENTS
Support by Lee County Commission LC001 ARA Grant
- No. 1ARA09-02 from Alabama Department of Economic
and Community Affairs (ADECA) to Lee County is gratefully acknowledged.
Cooperation and direct involvement by Lee County personnel is also acknowledged and appreciated
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QUESTIONS …
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