LONGTERM EXPERIENCE WITH PV POWER PLANTS IN GERMANY

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1 LONGTERM EXPERIENCE WITH PV POWER PLANTS IN GERMANY Dr. Christian Reise Fraunhofer Institute for Solar Energy Systems ISE Freiburg, Germany Solar Operations & Maintenance Milan, October 9 th, 2013

2 The Fraunhofer ISE Quality Circle Yield Assessments Module Measurements Quality Monitoring System tests 2

3 What are the questions? 3

4 What are the questions? What is the state-of-the-art performance of a PV power plant? What about degradation? What affects system reliability? 4

5 What are the questions? What is the state-of-the-art performance of a PV power plant? A review of 20+ years of commercial PV systems in Germany What about degradation? A study on 100+ power plants in Germany What affects system reliability? Modules / inverters / operation management 5

A review of 20+ years of commercial PV systems in Germany What about

6 PV support schemes in Germany 6

7 Development of system Performance Ratio in Germany A typical 5 kwp system installed in 1993 within the German 1000 Roofs Programme 7

8 Performance Ratio (PR): A simple Definition PR = 8

9 Development of system Performance Ratio in Germany 9

10 Development of system Performance Ratio in Germany 10

11 Development of system Performance Ratio in Germany Where is the limit? In Germany, state-of-the-art PV systems reach PR(si) values around 90% Note the difference of some 3 4% between PR(si) and PR(pyr) In southern Europe, PR will be reduced by 3 5% 11

12 Development of system Performance Ratio in Germany Where is the limit? In Germany, state-of-the-art PV systems reach PR(si) values around 90% Note the difference of some 3 4% between PR(si) and PR(pyr) In southern Europe, PR will be reduced by 3 5% PR = 12

13 Important factors for successful projects Lessons learnt Modules show rated power Maintenance of area Theft protection Minimized row to row shading 13

14 Important factors for successful projects Lessons learnt Modules show rated power Maintenance of area Theft protection Minimized row to row shading Minimized local shading Durable installation QC with commissioning Regular cleaning intervals Monitoring of operation 14

row to row shading Minimized local shading Durable installation QC

15 What are the questions? What is the state-of-the-art performance of a PV power plant? A review of 20+ years of commercial PV systems in Germany What about degradation? A study on 100+ power plants in Germany What affects system reliability? Modules / inverters / operation management 15

16 A study on 100+ power plants in Germany Data Handling Filtering of 5-min average values: 16

17 A study on 100+ power plants in Germany Data Handling Filtering of 5-min average values: Irradiance between W/m² 17

18 A study on 100+ power plants in Germany Data Handling Filtering of 5-min average values: Irradiance between W/m² Module temperature between C 18

19 A study on 100+ power plants in Germany Data Handling Filtering of 5-min average values: Irradiance between W/m² Module temperature between C Values inside median ± 5% 19

20 A study on 100+ power plants in Germany Data Handling Filtering of 5-min average values: Irradiance between W/m² Module temperature between C Values inside median ± 5% Calculation of rate of change rate in %/year 20

1000 W/m² Module temperature between 40 45 C Values

21 A study on 100+ power plants in Germany Example: a German 1000-Roofs-Programme system 5 kwp PV system built in 1993 New monitoring equipment in 2001 outliers excluded fitted linear slope Rate of Change: ca. 0.3%/a 21

22 A study on 100+ power plants in Germany Results statistics for c-si Calculation of a rate of change per year for each PV system shows large scatter Average c-si degradation rates are around 0.25% per year rate of change in % per year 4.0% 3.0% 2.0% 1.0% 0.0% -1.0% -2.0% -3.0% mono/poly -4.0% _ years of operation 22

23 A study on 100+ power plants in Germany Results for alternative silicon wafer technologies Average c-si degradation rates are around 0.25% per year Systems with EFG or string-ribbon modules reveal a tendency towards larger negative rates of change rate of change in % per year 4.0% 3.0% 2.0% 1.0% 0.0% -1.0% -2.0% -3.0% mono/poly EFG/String Ribbon -4.0% _ years of operation 23

24 What are the questions? What is the state-of-the-art performance of a PV power plant? A review of 20+ years of commercial PV systems in Germany What about degradation? A study on 100+ power plants in Germany What affects system reliability? Modules / inverters / operation management 24

25 What affects system reliability? On average, there are 5 incidents per PV power plant and year Source: meteocontrol, Augsburg, Germany 25

26 What affects system reliability? Module reliability BOS component & installation reliability Operation management 26

27 What affects system reliability? Module reliability no problem BOS component & installation reliability Commissioning tests Operation management Monitoring & intervention concepts 27

28 Commissioning tests Detailed on-site analysis of the entire power plant: Comprehensive visual inspection Thermographic imaging Measurement of actual PV power and conversion to Standard Test Conditions Assessment of Performance Ratio (PR) 28

29 System Inspection and Testing Verification of design data (module types, tilt angles, distances) Screening for large and small anomalies (insufficient foundation, cell grid faults) 29

30 System Inspection and Testing Mechanical problems Faulty mounting of modules Missing protection leading to cable damage 30

31 System Inspection and Testing Mechanical problems Loose connectors 31

32 System Inspection and Testing Mechanical problems Combination of connectors from different manufacturers Loose cables 32

33 System Inspection and Testing Mechanical problems Cable glands on top, moisture in the sub-distribution box Spare cable glands not sealed, moisture and animals in the box 33

34 System Inspection and Testing Infrared imaging Mobile lifting platform used for infrared camera imaging Temperature analysis of a large module field Temperature analysis of a solar module with defective cells 34

35 System Inspection and Testing Infrared imaging Detection of defective bypass diodes 35

36 System Inspection and Testing Infrared imaging Detection of defective terminals with high transition resistance 36

37 System Inspection and Testing Infrared imaging Detection of weak connections on power rails 37

38 Commissioning tests Detailed on-site analysis of the entire power plant: Comprehensive visual inspection Thermographic imaging Measurement of actual PV power and conversion to Standard Test Conditions Assessment of Performance Ratio (PR) 38

39 What affects system reliability? Module reliability no problem BOS component & installation reliability Commissioning tests Operation management Monitoring & intervention concepts 39

40 Operation management Monitoring & intervention Operation of a state-of-the-art supervisory control and data acquisition (SCADA) system in each PV power plant Operation of a dedicated control centre, offering all features needed to evaluate system operation and to optimize maintenance work flow Rapid reaction to error messages Management, performing and documentation of maintenance and repair On-site visits in regular intervals Landscape maintenance Learn more about operation management at this event 40

41 Conclusions PV power plant operation is well understood and reproducible Today s systems may reach PR(si) values around 90% in Central Europe Mono- and polycrystalline silicon systems show small degradation rates, by default, Fraunhofer ISE assumes 0.25% per year Long term success starts with a comprehensive system testing Only professional O&M concepts ensure high performance and yields 41

42 Thank you for your attention! Fraunhofer Institute for Solar Energy Systems ISE Dr. Christian Reise 42

43 Development of system Performance Ratio in Germany Comparison prediction vs. real world system operation 43

44 Development of system Performance Ratio in Germany Comparison prediction vs. real world system operation 44

Performance ratio. Contents. Quality factor for the PV plant

Performance ratio. Contents. Quality factor for the PV plant Performance ratio Quality factor for the PV plant Contents The performance ratio is one of the most important variables for evaluating the efficiency of a PV plant. Specifically, the performance ratio