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IEC 61724-1
Edition 2.0 2021-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Photovoltaic system performance –
Part 1: Monitoring
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IEC 61724-1
Edition 2.0 2021-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Photovoltaic system performance –
Part 1: Monitoring
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-5086-0
– 2 – IEC 61724-1:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references. 10
3 Terms and definitions . 11
4 Monitoring system classification . 16
5 General . 17
5.1 Measurement precision and uncertainty . 17
5.2 Calibration . 17
5.3 Repeated elements . 17
5.4 Power consumption . 17
5.5 Documentation . 17
5.6 Inspection . 18
6 Data acquisition timing and reporting . 18
6.1 Samples, records, and reports . 18
6.2 Timestamps . 20
6.3 Parameter names . 20
7 Measured parameters Required measurements . 21
8 Irradiance . 27
8.1 Sensor types . 31
8.2 General requirements . 31
8.2.1 Overview . 31
8.2.2 Sensor requirements . 31
8.2.3 Sensor locations . 32
8.2.4 Recalibration. 33
8.2.5 Soiling mitigation . 33
8.2.6 Dew and frost mitigation . 33
8.2.7 Inspection and maintenance . 34
8.2.8 Sensor alignment . 34
8.3 Measurements . 34
8.3.1 Global horizontal irradiance . 34
8.3.2 In-plane irradiance . 34
8.3.3 In-plane rear-side irradiance . 35
8.3.4 In-plane rear-side irradiance ratio . 35
8.3.5 Horizontal albedo . 35
8.3.6 Direct normal irradiance . 35
8.3.7 Diffuse horizontal irradiance . 35
8.3.8 Spectrally matched irradiance . 35
8.3.9 In-plane irradiance for concentrator systems . 36
8.3.10 Spectral irradiance for concentrator systems . 37
8.3.11 Circumsolar ratio measurements for concentrator systems . 37
8.3.12 Satellite remote sensing of irradiance . 38
9 Environmental factors . 39
9.1 PV module temperature . 39
9.2 Ambient air temperature . 41
9.3 Wind speed and direction . 42
9.4 Soiling ratio . 42
9.5 Rainfall . 45
9.6 Snow . 45
9.7 Humidity . 45
10 Tracker system . 45
10.1 Single-axis trackers . 45
10.2 Dual-axis trackers for >20x systems . 45
10.2.1 Monitoring . 45
10.2.2 Pointing error sensor alignment . 45
11 Electrical measurements . 46
11.1 Inverter-level measurements . 46
11.2 Plant-level measurements . 47
12 Data processing and quality check . 48
12.1 Daylight hours Night . 48
12.2 Quality check . 48
12.2.1 Removing invalid readings . 48
12.2.2 Treatment of missing data . 49
13 Calculated parameters . 49
13.1 Overview. 49
13.2 Summations . 50
13.3 Irradiation . 50
13.4 Electrical energy . 51
13.4.1 General . 51
13.4.2 DC output energy . 51
13.4.3 AC output energy . 51
13.5 Array power rating . 51
13.5.1 DC power rating . 51
13.5.2 AC power rating . 52
13.6 Yields . 52
13.6.1 General . 52
13.6.2 PV array energy yield . 52
13.6.3 Final system yield . 52
13.6.4 Reference yield . 52
13.6.5 Bifacial reference yield . 53
13.7 Yield losses . 53
13.7.1 General . 53
13.7.2 Array capture loss . 53
13.7.3 Balance of systems (BOS) loss. 53
13.8 Efficiencies . 54
13.8.1 Array (DC) efficiency . 54
13.8.2 System (AC) efficiency . 54
13.8.3 BOS efficiency . 54
14 Performance metrics . 54
14.1 Overview. 54
14.2 Summations . 55
14.3 Performance ratios . 55
14.3.1 Performance ratio . 55
– 4 – IEC 61724-1:2021 RLV © IEC 2021
14.3.2 Temperature-corrected performance ratios . 56
14.3.3 Bifacial performance ratios . 58
14.4 Performance indices . 59
15 Data filtering .
...