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2012 : Final Research Project

2012 : Final Research Project
Assessment of energy gain of double-axis over single-axis solar trackers

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Presentation Final Research Project Presentation Final Research Project Presentation Transcript

  • Thomas Maxime 2012
  • 2 Solar energy • Promising technology • Latitude and temperature True North Power, Ontario • Azimuth trackers • Wind & solar • Customers’ concerns • Need to assess different configurations
  • I) State of the art 1) Passive and active trackers 2) One axis and double axis trackers 3) Limits of the technology II) Solar radiation model Two solar models: Orgill and Pérez III) Computation of the solar model 1) Solar data 2) Different simulations 3) Modification of the model IV) Results of the simulation 1) Slope and azimuth of double axis tracker 2) Radiation on panel V) Discussion VI) Conclusion 3
  • 1) Passive and active solar trackers Passive • Gas under partial pressure • Memory of shape of an alloy • Temperature dependant • Bad with changing weather 4 Active • Time-based: from solar equations and modeling • Experimental: optical sensors • Optimization • Not weather dependant The identical tubes are filled with gas
  • 2) Single and double-axis trackers Single-axis • Different configurations • Fixed slope • Rotation 2° every 8min • Around 28% energy gain 5 Double axis • Rotation of two axis: azimuth+slope • Energy gain>40% around sunrise and sunset • Around 32% energy gain
  • 3) Limits of the technology Possible improvement of azimuth tracker • Monthly hand-tilting = 3.1% energy gain • One hour step = 99.75% • Two hour step = 98.80% • Two step tracker = 95% 6 • Double axis = 5-6% gain against 2-3% consumption of total energy due to addition of a motor • Costs and maintenance • Cloudy days: diffuse radiation only of continuous azimuth tracking Continuous Two step Fixed tilt
  • 7 Ipanel = Idiffuse + Ibeam + Ireflected
  • 8 Orgill model Iground + Solar equations + Latitude+longitude Idiffuse + Ibeam Pérez model Idpanel + Ibpanel + Ireflectpanel Ipanel Idiffuse + Ibeam + Panel’s slope and azimuth First step model Second step model Measured total radiation on horizontal surface: Iground
  • 1) Solar data • Queen’s University, Kingston • One minute measurement of solar horizontal radiation for 2011 • 44.225°N 76.495°W 2) Different simulations • Fixed South facing panel with optimum slope • Azimuth tracker with ∆az=1° and optimum slope • Double-axis tracker with ∆az=1° and ∆β=[1,2,5,10°] • Perfect continuous tracker θ=0° 9
  • 3) Modification of the model • Problem at sunrise and sunset, assumption: Ibeam=0 and Idiffuse=Iground • Two cases: Pérez model + Liu & Jordan for Zenith angle > 85° or Pérez model all the time 10 Orgill model Pérez model Pérez model Liu & Jordan model Zenith angle > 85°Zenith angle ≤ 85° OR Ipanel Ipanel
  • 1) Slope and azimuth of double axis 11 Δaz=Δβ=1°
  • 2) Radiation on panel 12 Pérez + Liu & Jordan when Zenith angle>85° Continuous 100,00% 132,54% Two axis with ∆az=1° 1° 99,99% 132,53% 2° 98,87% 131,04% 5° 98,78% 130,92% 10° 98,48% 130,52% One axis ∆az=1° fixed slope 50° 97,14% 128,75% Fixed slope 0° south 34° 75,45% 100,00% • Two-axis tracker increases energy gain from 28.75% to 32.53% compared to fixed panel facing south • Only 1.73% gain of two-axis over one-axis with Δβ=2° • Maximum gain of 2.85% with a very accurate tracking
  • 13 Use of Pérez + Liu & Jordan • Received radiation for Zenith angle>85° represents only 1.96% of total radiation on horizontal surface on earth. • Comparison with 5 other sites in the USA with 43°<latitude<45.5° and 70°<longitude<83° Syracuse, New York Rochester, New York Concord, New Hampshire Burlington, Vermont Massena, New York • Fixed panel: consistent slope of 34° USA sites Queen’s University Two-axis tracker 32.9% 32.53% Azimuth tracker 28.8% 28.75% Energy gain over fixed south facing panel Queen’s University: 44.225°N 76.495°W
  • 14 Uncertainty of the solar model • 6.7% difference between use of Pérez or use of Pérez + Liu & Jordan for continuous tracking • High resolution data: error around sunrise and sunset & 5W/m² measurement precision • Geography of the site: top of a mountain? Shadow? Feasibility of addition of a second axis • 2.85% energy gain of two axis over azimuth tracker against 2% motor consumption. Need of battery? • 2.85% with very accurate tracking. Use of the motor • Additional costs and maintenance
  • 15 Is it worth adding a second axis? • Small energy gain • Big uncertainty in solar models • Additional costs Solar tracker = optimized PV panels • Gain of a few percent • Better in sunny weather • No need for perfect tracking
  • 16