iecec lee county justice center-presentation

8/8/2019 IECEC Lee County Justice Center-Presentation

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Space Research Institute 8th International Energy Conversion Engineering Conference

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 University

Henry W. Brandhorst, Jr.

Carbon-Free Energy, LLC

July 28, 2010


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Outline

Project Overview

Objectives

Why Now

Initial Modeling

System Component Selection

System Modeling

Data Collection and Analysis

Summary


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Project Overview

Lee Countys 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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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 systems 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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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 installingphotovoltaic (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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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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Solar Array System AnalysisLoad Monitoring

Electronic load monitoring and data logging

of 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 inthe 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

optimize design, and compare to predicted

performance

Electrical inverter specifications determined


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Solar Array System AnalysisPV 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

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$/Watt

Watts

mc-Si Modules

c-Si Modules

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Watts/(Ft^2)

Dollars

mc-Si Modules

C-Si Modules


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Solar Array System AnalysisCAD 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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Solar Array System AnalysisCAD Model of LCJC Detention Center

Room to install nowand/or expand in future

Some public visibility

is important to this

installation

Large, mostly unobstructed

north/south-aligned flat roof


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Solar Array System AnalysisShadow Study Analysis on Roof Mounts w/SketchUp

Winter Solstice

Summer Solstice


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Solar Array System AnalysisPV Design Pro-G Modeling

Selected Inputs

220 W SunPower Panels

480 V Solectria PVI-13kW Inverter

30-year weather profile database forMontgomery, 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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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 20, 25, 32 (latitude), 40, and 50

Another panel will be a control panel that is fixed facing south at latitude tilt


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LCJC PV Array Project Layout

System completion and certification, June 29, 2009


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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 Solectrias SolrenView site

Pole Array: SunPower SPR3000m 3kW, 208

VAC

Inverter output from SMAs SunnyPortal site

SMAs WebBox and SensorBox collect both

roof and pole array environment data onto

SMAs 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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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 227Jun 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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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 467seedlings 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

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AC

Energy(kWh)

Pole Array

Roof Array

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Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09 Jan-10 Feb-10 Mar-10 Apr-10 May-10 Jun-10

ACEnergy(kWh)

LCJC Actual Performace Data Compared to Modeling Predictions

Actual Array Performance

PVSYST

Design Pro G

PV Watts


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AC Power Produced July 12-18th

Week

demonstrates alldifferent types of

weather patterns

Power profiles

vary due to cloudcover and storm

fronts


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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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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

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Ins

olation(kWh/m2)

Insolation Data Pole Array

LCJC Pole Actual

PV Watts Pole

Design Pro G Pole

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Ins

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Insolation Data Roof Array

LCJC Roof Actual

PV Watts Roof

Design Pro G Roof


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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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Summary

This paper has used the data collected at the Lee Countys T.K.Davis Justice Center 16.6 kW grid-connected solar-powered systemand analyzed it to find trends and anomalies

Compared the performance data to the results of photovoltaicmodeling programs that were used before and during installation ofthe system

The accuracy is quite good

Currently the system is producing about 5-7% more power for two detailedmodeling 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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Lee Countys Example

Alabamas 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 projects 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 LeeCountys website at http://www.leeco.us/solar_project/index.html


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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

SPACE

RESEA RCH

INST ITUTEAuburn University

iecec lee county justice center-presentation

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