Solmetric PVA-600 PV Analyzer

Transcription

1 Introducing the Solmetric PVA-600 PV Analyzer Paul Hernday PV Applications Engineer Bryan Bass Sales Engineer

2 Topics Introduction to Solmetric Verifying PV array performance Applications Introduction to I-V curves PV models Irradiance and temperature sensing PV Analyzer Features & operation Example measurements Troubleshooting example

3 Solmetric Corporation Founded in employees Headquarters in Sebastopol, California Mission: Improve the effectiveness of solar systems and those who install them by providing high quality, easy-to-use, accurate tools with embedded technical know-how.

4 Solmetric Solutions

5 Topics Introduction to Solmetric Verifying PV array performance Applications Introduction to I-V curves PV models Irradiance and temperature sensing PV Analyzer Features & operation Example measurements Troubleshooting example

6 Why verify PV array performance? Find & fix array problems early Speed up the commissioning of new systems Check the health of older PV arrays Speed up troubleshooting Localize problems to PV modules or inverter Provide data for PV module warranty claims

7 PV Analyzer Applications Preliminary assessment Site survey Preliminary design Proposal Contract Final design Installation planning Installation Checkout Startup Performance Verification/ Commissioning Maintenance Service

8 Performance Verification Tools A spectrum of solutions Verification: Measurements compared with predictions Inverter readout compared with expected Pac DC measurements compared with simple model String monitors I-V curve measurements compared with a detailed model Basic Comprehensive

9 Benefits of measuring I-V curves Provides better diagnostic value Measures the entire I-V signature of the string Comparison with PV models tells you more Automated measurement Fast No manual record keeping (less chance of mistakes) Safely measures short circuit current I-V measurement will become a PV industry best practice

10 Current I-V curves Isc Imp Max Power Point Area A = Imp x Vmp Area B = Isc x Voc Voltage Vmp Voc Fill Factor = Area A / Area B (represents the square-ness of the I-V curve) Copyright Solmetric 2009

11 Current Series and Shunt Losses Isc Imp Shunt loss Max Power Point Series loss Voltage Vmp Voc Copyright Solmetric 2009

12 Mismatch Losses (in this example, we intentionally shaded entire modules) Thanks to the Solar Division of Harmony Farm Supply for access to this PV system (2 strings of 10 modules)

13 Topics Introduction to Solmetric Verifying PV array performance Applications Introduction to I-V curves PV models Irradiance and temperature sensing PV Analyzer Features & operation Example measurements Troubleshooting example

14 PV System Verification Solmetric PV Analyzer

15 I-V Measurement Unit Wirelessly linked to user s PC

16 PC with wireless USB adaptor User provides the PC. Samsung Q1 Ultra shown here.

17 Optional wireless sensor kit Sensors and wireless adaptors

18 PVA-600 Block Diagram Charging connector (isolated) CPU & wireless module* C (1 of 3) V sense I sense Control button w LED (isolated) * Jennic IEEE Capacitive I-V method High-value capacitors better accuracy with high-efficiency PV modules Electrically isolated, system ground not required Protected against over-voltage, -current, -temperature, & reverse polarity

19 Example measurement setup Measuring strings at a combiner box

20 Testing at fused DC buss taps US Coast Guard PV array in Petaluma, CA

21 Testing at combiner boxes 860kW System at Portland Habilitation Center, by Dynalectric

22 Testing at combiner boxes 860kW System at Portland Habilitation Center, by Dynalectric

23 Testing a PV Array with the Solmetric PV Analyzer 1. Set up the PV model and save it to your PC 2. Set up the array tree and save it to your PC Save time in the field by doing this ahead of time, back at the office. 3. Open the DC disconnect to isolate the combiner box 4. Lift the fuses to de-energize the combiner buss bars 5. Clip the PV Analyzer onto the combiner buss bars 6. Place the irradiance & temperature sensors 7. Measure the strings a) Insert a fuse b) Press Measure Now c) Observe and save results

24 PVA-600 Specifications Max DC input voltage: 600V Max DC input current: 20A Maximum DC power: 12 kw (instantaneous) Min Voc: 20V Min Isc: 1A I-V measurement time: 0.03 to 1.0s I-V update: User triggered (except in logging mode) Points per I-V trace (typ): * * Depends upon instrument range and details of test device.

25 On-board PV models For predicting PV module/string performance Sandia National Labs PV Array Model Most comprehensive (30 + parameters) Parameters measured by an independent lab ~400 modules characterized, more starting ~ June Parameter Model Developed at U. Wisconsin, used by CEC for NSHP program Parameters calculated from module data sheet values ~2000 modules covered at this time Single-point efficiency model Translates Pmax (STC) to actual irradiance & temp User enters data sheet parameters

26 Temperature and Irradiance (plane of array) Inputs The PV models take sensor inputs from: Wireless sensors (optional kit) Manual entry (from a hand-held instruments) Calculated from measured I-V curve* ( array as sensor mode) * Borrows from the Sandia PV model and IEC : Equivalent Cell Temperature

27 Example of array-as-sensor application PV module with series resistance problem

28 Ordering Information

29 Solmetric PV Analyzer User Interface

30 Traces tab Measured vs predicted (red dots) Shaded area is the inverter s DC input voltage range

31 Verify tab For quick performance checking

32 Table tab For tabular comparisons

33 Logging tab (PC required) Predicted Measured Max measured

34 Setting up the PV model

35 Example measurement results Mismatch losses (eg shading) Series losses Shunt losses

36 Partial shading Business card on one cell in string of 15, 48-cell modules

37 Series Losses Simulated by adding external series resistors

38 PV string with no added series resistance 2 strings of 10 Sharp NT-175U1 modules, portrait mode 419 2Jul

39 Add 0.5 ohm series resistance 422 2Jul

40 Add 1.0 ohm series resistance

41 Extreme case: PV module with 2.5 ohm added series resistance

42 Shunt Losses Simulated with external shunt resistance

43 PV module with 100 ohm shunt resistor

44 Troubleshooting Example

45 Current - A Abnormal I-V curve (red) And curve of neighboring string (blue) for comparison String 4B14 String 4B Voltage - V

46 Damaged cell in string 4B14

47 I-V curve of module with damaged cell High series resistance

48 Topics Introduction to Solmetric Verifying PV array performance Applications Introduction to I-V curves PV models Irradiance and temperature sensing PV Analyzer Features & operation Example measurements Troubleshooting example

49 For More Information