2014 PV Performance Modeling Workshop: PVSim Update: Mike Anderson, SunPower Corporation

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2014 PV Performance Modeling Workshop: PVSim Update: Mike Anderson, SunPower Corporation

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2014 PV Performance Modeling Workshop: PVSim Update: Mike Anderson, SunPower Corporation

  1. 1. PVSim Update Mike Anderson Presented at the 2014 Sandia PV Performance Modeling Workshop Santa Clara, CA. May 5, 2014 Published by Sandia National Laboratories with the Permission of the Author
  2. 2. 2© 2013 SunPower Corporation Recent Updates Updated the Soiling Loss Model Added new Snow Loss Model • SunPower-designed simulator • Free web-based access to: – SunPower employees – Partners and dealers – External parties (upon request)
  3. 3. 3© 2013 SunPower Corporation Dynamic Soiling Loss Model Previous Model New Model Environment User selection (NorCal/SoCal/Central, Urban/Suburban/Rural) Based on Lat/Lon (Koppen- Geiger classification) - allows for user adjustment System type No distinction System tilt dependence Coverage California Global Validation basis 46 systems, 1 year 150 systems, 6 years average (~20x more data)
  4. 4. 4© 2013 SunPower Corporation Soiling Loss Model Central California Hawaii
  5. 5. 5© 2013 SunPower Corporation Soiling Loss Model
  6. 6. 6© 2013 SunPower Corporation Snow Loss Model Accumulation ∆𝑆𝐷 𝑃𝑉𝑎𝑐𝑐𝑢𝑚= ∆𝑆𝐷 𝐺 × 𝑐𝑜𝑠𝛽 (∆𝑆𝐷 𝐺> 0) Where: ∆𝑆𝐷 𝐺 = change in snow depth on the ground, and 𝛽 = slope of the PV from horizontal Melting ∆𝑆𝐷 𝑃𝑉𝑚𝑒𝑙𝑡= ∆𝑆𝐷 𝐺𝑚𝑒𝑙𝑡 × 𝑐𝑜𝑠𝜃 𝑐𝑜𝑠𝜃 𝑧 (∆𝑆𝐷 𝐺< 0) Where: 𝜃 = incidence angle between the sun and normal to the PV (at solar noon) 𝜃𝑧 = incidence angle between the sun and normal to the ground (zenith angle) (at solar noon) Combined 𝑆𝐷 𝑃𝑉 = 𝑆𝐷 𝑃𝑉𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠 +∆𝑆𝐷 𝑃𝑉𝑎𝑐𝑐𝑢𝑚 + ∆𝑆𝐷 𝑃𝑉𝑚𝑒𝑙𝑡 Where: 𝑆𝐷 𝑃𝑉 = current snow depth on the PV 𝑆𝐷 𝑃𝑉𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠 = previous snow depth on the PV (last iteration)
  7. 7. 7© 2013 SunPower Corporation Snow Loss Model Sliding 𝛽𝑐𝑟𝑖𝑡 = 𝑡𝑎𝑛−1 𝜇 𝑠 = ~8 Angle of repose for snow is approximately 38 -assumed 45 shed pile Coefficient of static friction Coefficient of dynamic friction Waxed wood on wet snow 0.14 0.1 Waxed wood on dry snow 0.04 Non-waxed wood on snow 0.5 0.3
  8. 8. 8© 2013 SunPower Corporation Snow Loss Model • Validation based on 3 years of operation at 21 sites (60 systems) – Tracker systems – Fixed ground and roof systems ranging from 0 to 25 degrees
  9. 9. 9© 2013 SunPower Corporation Snow Loss Model T0 Tracker
  10. 10. 10© 2013 SunPower Corporation Snow Loss Model Fixed 0 degrees

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