Graduate Category: Engineering & Technology Degree Level: Ph.D ...
Graduate Category: Engineering & Technology Degree Level: Ph.D. Abstract ID# 361
A Smart Tracking algorithm for dual-axis photovoltaic (PV) arrays Stephanie White Quinn Department of Electrical and Computer Engineering Abstract
Results
A 2-axis photovoltaic (PV) array efficiently converts solar energy into electrical power on sunny days by tracking the sun. However, the array is sometimes positioned at a nonoptimal angle on cloudy days, and thus fails to collect the maximum available irradiation. This research is focused on finding the optimal angle of a time-position 2-axis tracking PV array under various cloud conditions in order to maximize total irradiance and electrical power. We propose a “Smart Tracking” algorithm for 2-axis PV arrays.
Numerical calculations in MATLab using historical weather data Yearly irradiance increases 1.55 to 3.48% when a 2-axis tracking PV array is positioned at a shallower angle during cloudy periods. +2.76% International Falls, MN
Background The amount of solar radiation incident on a surface is the sum of several radiation streams: • Beam radiation (Eb) from the sun.
+1.87% Boston, MA
Solar radiation (kWh/m2/day)
+1.55% Asheville, NC Solar Photovoltaic Resources for the U.S (from http://maps.nrel.gov/femp_atlas)
Thirty-four 2-axis PV arrays are located at Middlebury College. Weather and electrical power data are recorded every 15 minutes. Using the PV_LIB toolbox in MATLab, we analyzed 4 months of weather and power data. We found that: AC power increased as much as 4% during cloudy periods when using Smart Tracking.
Eb Er
Ed
Level 3: Grand challenges
Position a tracking PV array to maximize the electricity produced under different weather conditions.
Level 2: Test beds
Build an experimental prototype of Smart Tracking PV array.
Level 1: Fundamental Research
Equation relating the optimal position of a tracking array to weather conditions.
Improve efficiency of 1-axis and 2-axis tracking PV arrays at minimal cost.
Demonstrate effectively the feasibility of Smart Tracking to stakeholders.
Field test of Smart Tracking at a 2-axis tracking PV array.
Validate Smart Tracking approach at multiple tracking PV arrays in different locations.
Fraction of diffuse irradiation stream to total irradiation for all locations.
Method for using weather sensor data to control array’s position.
Barriers B1. Identify correct correlation for fraction of diffuse irradiance in total irradiance. B2. Mechanically move array to within 3 degrees of optimal tilt to capture 99.9% irradiance.
System level (red) defines our grand system challenges Testing level (blue) validates research outcomes. Research level (green) defines distinct research thrusts.
Our results indicate that the irradiance collected by a 2-axis tracking PV array may be increased by adjusting the tilt angle to a shallower angle during cloudy weather. Numerical calculations indicate that the yearly irradiance could increase 1 to 3.5%. Analysis of weather and power data from a solar installation in Vermont indicate that the increase in AC power could be as much as 4% depending on cloud conditions.
4.00
Next steps: Testing of the Smart Tracking approach
3.00 2.00
Nov. 7, 2013
We plan to build an experimental time-position 2-axis PV array and test the Smart Tracking algorithm that we are developing. Parts and materials will be purchased using a Prototype Fund Grant from NEU’s IDEA Venture Accelerator.
1.00 0.00
• Reflected radiation (Er) – reflected from the ground. On cloudy days, most of the irradiation on the PV array is diffuse irradiation.
Smart Tracking for 2-axis PV arrays
Conclusion
Analysis of a 143 kW solar farm in Middlebury, Vermont
% increase
• Diffuse radiation (Ed) which is scattered sunlight.
+2.57% Burlington, VT
+3.48% Quillayute, WA
On clear, sunny days, the Smart Tracking array uses the conventional 2-axis tracking angles to point directly at the sun.
But on cloudy days, the Smart Tracking array adjusts to an optimal angle and collects more irradiance.
3-Level Research Plan
Total monthly AC energy increased by 1.07 to 1.74% using Smart Tracking. 16000 14000 12000 10000 AC Energy 8000 6000 (kWh) 4000 2000 0
Standard 2-axis Smart Tracking 2-axis
+1.10%
+ 1.74%
+1.17%
Acknowledgments The assistance of Professor Rich Wolfson of Middlebury College in providing access to power and weather data from Middlebury College’s solar installation is gratefully acknowledged.
+1.07%
References [1] J. A. Duffie and W. A. Beckman, Solar Engineering of Thermal Processes, 3rd ed. Hoboken, NJ: John Wiley & Sons, Inc., 2006. Nov-13
Dec-13
Jan-14
Feb-14
A Smart Tracking algorithm for dual-axis photovoltaic (PV) arrays Stephanie White Quinn Department of Electrical and Computer Engineering Abstract
Results
A 2-axis photovoltaic (PV) array efficiently converts solar energy into electrical power on sunny days by tracking the sun. However, the array is sometimes positioned at a nonoptimal angle on cloudy days, and thus fails to collect the maximum available irradiation. This research is focused on finding the optimal angle of a time-position 2-axis tracking PV array under various cloud conditions in order to maximize total irradiance and electrical power. We propose a “Smart Tracking” algorithm for 2-axis PV arrays.
Numerical calculations in MATLab using historical weather data Yearly irradiance increases 1.55 to 3.48% when a 2-axis tracking PV array is positioned at a shallower angle during cloudy periods. +2.76% International Falls, MN
Background The amount of solar radiation incident on a surface is the sum of several radiation streams: • Beam radiation (Eb) from the sun.
+1.87% Boston, MA
Solar radiation (kWh/m2/day)
+1.55% Asheville, NC Solar Photovoltaic Resources for the U.S (from http://maps.nrel.gov/femp_atlas)
Thirty-four 2-axis PV arrays are located at Middlebury College. Weather and electrical power data are recorded every 15 minutes. Using the PV_LIB toolbox in MATLab, we analyzed 4 months of weather and power data. We found that: AC power increased as much as 4% during cloudy periods when using Smart Tracking.
Eb Er
Ed
Level 3: Grand challenges
Position a tracking PV array to maximize the electricity produced under different weather conditions.
Level 2: Test beds
Build an experimental prototype of Smart Tracking PV array.
Level 1: Fundamental Research
Equation relating the optimal position of a tracking array to weather conditions.
Improve efficiency of 1-axis and 2-axis tracking PV arrays at minimal cost.
Demonstrate effectively the feasibility of Smart Tracking to stakeholders.
Field test of Smart Tracking at a 2-axis tracking PV array.
Validate Smart Tracking approach at multiple tracking PV arrays in different locations.
Fraction of diffuse irradiation stream to total irradiation for all locations.
Method for using weather sensor data to control array’s position.
Barriers B1. Identify correct correlation for fraction of diffuse irradiance in total irradiance. B2. Mechanically move array to within 3 degrees of optimal tilt to capture 99.9% irradiance.
System level (red) defines our grand system challenges Testing level (blue) validates research outcomes. Research level (green) defines distinct research thrusts.
Our results indicate that the irradiance collected by a 2-axis tracking PV array may be increased by adjusting the tilt angle to a shallower angle during cloudy weather. Numerical calculations indicate that the yearly irradiance could increase 1 to 3.5%. Analysis of weather and power data from a solar installation in Vermont indicate that the increase in AC power could be as much as 4% depending on cloud conditions.
4.00
Next steps: Testing of the Smart Tracking approach
3.00 2.00
Nov. 7, 2013
We plan to build an experimental time-position 2-axis PV array and test the Smart Tracking algorithm that we are developing. Parts and materials will be purchased using a Prototype Fund Grant from NEU’s IDEA Venture Accelerator.
1.00 0.00
• Reflected radiation (Er) – reflected from the ground. On cloudy days, most of the irradiation on the PV array is diffuse irradiation.
Smart Tracking for 2-axis PV arrays
Conclusion
Analysis of a 143 kW solar farm in Middlebury, Vermont
% increase
• Diffuse radiation (Ed) which is scattered sunlight.
+2.57% Burlington, VT
+3.48% Quillayute, WA
On clear, sunny days, the Smart Tracking array uses the conventional 2-axis tracking angles to point directly at the sun.
But on cloudy days, the Smart Tracking array adjusts to an optimal angle and collects more irradiance.
3-Level Research Plan
Total monthly AC energy increased by 1.07 to 1.74% using Smart Tracking. 16000 14000 12000 10000 AC Energy 8000 6000 (kWh) 4000 2000 0
Standard 2-axis Smart Tracking 2-axis
+1.10%
+ 1.74%
+1.17%
Acknowledgments The assistance of Professor Rich Wolfson of Middlebury College in providing access to power and weather data from Middlebury College’s solar installation is gratefully acknowledged.
+1.07%
References [1] J. A. Duffie and W. A. Beckman, Solar Engineering of Thermal Processes, 3rd ed. Hoboken, NJ: John Wiley & Sons, Inc., 2006. Nov-13
Dec-13
Jan-14
Feb-14
