2014 PV Performance Modeling Workshop: Irradiance- and Temperature-dependent PV Module Performance Measurement: Rajeev Singh, PV Evolution Labs

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2014 PV Performance Modeling Workshop: Irradiance- and Temperature-dependent PV Module Performance Measurement: Rajeev Singh, PV Evolution Labs

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2014 PV Performance Modeling Workshop: Irradiance- and Temperature-dependent PV Module Performance Measurement: Rajeev Singh, PV Evolution Labs

  1. 1. www.PVEL.com 1www.PVEL.com 1 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 1www.PVEL.com 1www.PVEL.com 1 Click to edit Master title style Irradiance- and Temperature-dependent PV Module Performance Measurement Rajeev Singh, John Watts 2014 PV Module Performance Modeling Workshop May 5, 2014
  2. 2. www.PVEL.com 2www.PVEL.com 2 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 2www.PVEL.com 2www.PVEL.com 2 Review of IEC standards specifying temperature-dependent PV module performance measurement Issues with outdoor measurement of temperature coefficients Indoor vs. outdoor measurements Variables of irradiance- and temperature-dependent PV module performance measurements PVEL’s indoor measurement approaches WHY IS THERE VARIABILITY?Outline
  3. 3. www.PVEL.com 3www.PVEL.com 3 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 3www.PVEL.com 3www.PVEL.com 3 Standards specify linear reference devices to set/determine irradiance Spectral control or correction is required WHY IS THERE VARIABILITY?IEC Standards: Irradiance Standard Stated Purpose Indoor / Outdoor Simulator Class Irradiance Reference Spectral Correction IEC 60904-1 2006 I-V Measurement Both BBB Linear Yes IEC 60891 2009 G & T Corrections to I-V Linear Yes IEC 61853-1 2010 PMAX(G,T) Linear Yes IEC 61215/61646 2005 Module Qualification Linear Do not alter
  4. 4. www.PVEL.com 4www.PVEL.com 4 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 4www.PVEL.com 4www.PVEL.com 4 Standards insufficiently specify temperature control methods and their caveats Poor harmony regarding temperature measurement approach Cell temperature measurement methods are not discussed In-plane temperature uniformity is specified in only one instance WHY IS THERE VARIABILITY?IEC Standards: Temperature Standard Year Stated Purpose Indoor / Outdoor Simulator Class Temperature Control Guidance Measurement Method Number of Sensors Sensor Location (Backsheet or Cell) Temperature Uniformity Requirement IEC 60904-5 2011 Equivalent Cell Temperature (ECT) Both BBB None VOC and β N/A N/A No IEC 60904-1 2006 I-V Measurement Sensor or ECT ? ? No IEC 60891 2009 G & T Corrections to I-V Sensor 4 (Averaged) ? ± 2 °C IEC 61853-1 2010 PMAX(G,T) Sensor or ECT 3 (Averaged) ? No IEC 61215/61646 2005 Module Qualification Sensor ? ? No
  5. 5. www.PVEL.com 5www.PVEL.com 5 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 5www.PVEL.com 5www.PVEL.com 5 WHY IS THERE VARIABILITY? Outdoor Backsheet-referenced Temperature Coefficients Measurement RBS: Thermal resistance of back-side EVA, backsheet ∆𝑇 = 𝑄𝑅𝑡ℎ 20 30 40 50 60 0 5 10 15 20 25 30 35 40 Backsheet Temperature (°C) Cell Temperature (°C) Temperature(°C) Measurement Time (arb.) Results in overestimation of temperature coefficient magnitudes
  6. 6. www.PVEL.com 6www.PVEL.com 6 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 6www.PVEL.com 6www.PVEL.com 6 WHY IS THERE VARIABILITY? Outdoor Measurement of VOC(T) – Beta (β) -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 1NoBox 2NoBox 3NoBox 4NoBox 1ThermalBox 2ThermalBox 3ThermalBox 4ThermalBox Outdoor Measurement Results Cell Probe BS Probe 2 BS Probe 3 BS Probe 4 BS Probe 5 Measured(%/°C) Trial Backsheet view of test module temperature probe locations Cell probe (CP) is a hypodermic thermocouple needle inserted underneath backsheet and contacting cell busbar Backsheet (BSx) probes are standard thermocouples adhered to backsheet using Kapton (polyimide) tape CP 2 3 54 J-BOX In-plane temperature uniformity is poor 𝑑𝑇 𝑑𝑡 𝑥, 𝑦 varies with position VOC(T) is often nonlinear
  7. 7. www.PVEL.com 7www.PVEL.com 7 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 7www.PVEL.com 7www.PVEL.com 7 Indoor Flash Test Good in-plane temperature uniformity Steady-state Stable irradiance Uncollimated light Non-uniform irradiance Class A+: ≤ 1 % Not AM1.5 Class A+: ± 12.5 %) WHY IS THERE VARIABILITY?Indoor Flash Testing vs. Outdoor Outdoor Poor in-plane temperature uniformity Not steady-state Possibly stable irradiance 2-axis tracker Collimated light Uniform irradiance Possibly AM1.5
  8. 8. www.PVEL.com 8www.PVEL.com 8 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 8www.PVEL.com 8www.PVEL.com 8 Irradiance-dependent Constant spectrum throughout range Neutral density filters Constant bulb power Power accuracy Linear feedback WHY IS THERE VARIABILITY?Specific Lab. Measurement Variables Temperature-dependent In-plane uniformity Controlled environment, flash tester Steady-state Controlled environment, flash tester Measurement location Cell temperature probe or isothermal conditions
  9. 9. www.PVEL.com 9www.PVEL.com 9 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 9www.PVEL.com 9www.PVEL.com 9 WHY IS THERE VARIABILITY?Indoor Measurement Techniques Cell temperature probes Exposed optical surface In-plane uniformity: ± 2 °C Back-side Heating Uniform Heating Backsheet temperature probes Glass window In-plane uniformity: ± 0.5 °C
  10. 10. www.PVEL.com 10www.PVEL.com 10 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 10www.PVEL.com 10www.PVEL.com 10 WHY IS THERE VARIABILITY?Irradiance Control -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 0 200 400 600 800 1000 1200 Residual(%) Irradiance (W/m 2 ) IEC 61853-1 ISC Residuals Irradiance sensor (feedback) calibrated at 1000 W/m2 IEC 60904-10: < 2 % non-linearity PVEL: < 1 % non-linearity at all temperatures and throughout irradiance range
  11. 11. www.PVEL.com 11www.PVEL.com 11 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 11www.PVEL.com 11www.PVEL.com 11 WHY IS THERE VARIABILITY?Temperature Control 8.05 8.1 8.15 8.2 8.25 8.3 20 25 30 35 40 45 50 55 PVEL Measurement of Scheuten Multisol P6-54c Isc(T) y = 7.9475 + 0.0055727x R= 0.99953 Isc(A) Temperature (°C) 20 30 40 50 60 0 50 100 150 BS #1 BS #2 BS #3 BS #4 BS #5 C Temperature(°C) Time (minute)
  12. 12. www.PVEL.com 12www.PVEL.com 12 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 12www.PVEL.com 12www.PVEL.com 12 IEC measurement standards acceptably address irradiance- dependent measurements but do not provide adequate treatment of temperature-dependent measurement consideration Outdoor measurement accuracy is difficult to achieve PVEL has developed in-house methods to improve temperature-dependent measurement accuracies PVEL’s temperature coefficients measurements indicate that datasheet coefficients are overestimated in magnitude PVEL’s state-of-the-art measurement system will be online in May 2014 Compare back-side heating method to isothermal chamber system Conclusions
  13. 13. www.PVEL.com 13www.PVEL.com 13 Copyright © 2014 PV Evolution Labs. All rights reserved www.PVEL.com 13www.PVEL.com 13www.PVEL.com 13 Click to edit Master title style Rajeev@PVEL.com John@PVEL.com Thank You

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