Iec 61724

Monitoring System Performance

Venue: PV Module Reliability Workshop Presenter: Keith Emery and Ryan Smith Date: February 16, 2011
NREL/PR-5200-50643

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Outline
Standards
– National Electric Code – IEC 60904-1“Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage characteristics” – IEC 61724 “Photovoltaic System Performance Monitoring – Guidelines for Measurement, Data Exchange and Analysis” – IEC 61829 “Crystalline Silicon Photovoltaic array – On-site Measurement of I-V Characteristics” – ASTM E1036 “Standard Test Methods for Electrical Performance of Nonconcentrator Terrestrial PhotovoltaicModules and Arrays Using Reference Cells” – ASTM E2527 “Standard Test Method for Electrical Performance of Concentrator Terrestrial Photovoltaic Modules and Systems Under Natural Sunlight” – ASTM WK22009 “Reporting Photovoltaic Non-Concentrator System Performance “

Sources of Uncertainty NREL’s Approach to Local and Remote System Monitoring Summary
NATIONAL RENEWABLE ENERGY LABORATORY

2IEC 60904-1 “Photovoltaic devices – Part 1: Measurement of Photovoltaic Current-Voltage Characteristics

• Voltage and Current measured with ±0.2 % Uncertainty in Voc and Isc • Test and Reference device coplanar within ±2° and normal to the sun within ±5°. • Reference cell and test device temperature measured with ±1 °C uncertainty. • Optionally test device temperature determined viaequivalent cell temperature method (IEC 60904-5) • Spectral mismatch error correction if matched reference cell not used (IEC 60904-7). • If reference cell >2 °C from calibration temperature corrections applied. • Use IEC 60891 to translate for temperature and irradiance
NATIONAL RENEWABLE ENERGY LABORATORY

3

ASTM E1036 “Standard Test Methods for Electrical for Electrical Performance ofNonconcentrating Photovoltaic Modules and Arrays Using Reference cells”

• Voltage and Current measured with ±0.1 % Uncertainty and 0.05% Resolution for Voc and Isc. • Test and Reference device coplanar within ±2° and normal to the sun within ±10° or report incidence angle. • Reference cell and test device temperature measured with ±1 °C uncertainty, 0.1 °C resolution. • Spectral mismatch errorcorrection applied (ASTM E973). • Temperature and irradiance corrections applied if temperature more than 2°C from reference temperature or irradiance > 5% from reference irradiance correct using bilinear method. Otherwise current corrected to constant irradiance. • Average Wind speed for 5 min prior to test.

NATIONAL RENEWABLE ENERGY LABORATORY

4

IEC 61724 “Photovoltaic System PerformanceMonitoring – Guidelines for measurement data exchange and analysis”

Meteorology

Photovoltaic array
– – – – –

– Total irradiance, in the plane of the array – Ambient air temperature – Wind speed Output voltage Output current Output power Module temperature Mounting / tracker characteristics

Energy storage
– Operating voltage – Current to/from storage – Power to/from storage

Utilitygrid
– Utility voltage – Each phase - Current to/from utility grid – Power to/from utility grid

Load

– Load voltage – Load current – Load power

Back-up sources
– Output voltage – Output current – Output power

NATIONAL RENEWABLE ENERGY LABORATORY

5

Meteorology
DC Disconnect

DC Monitoring
(V, I)

PV array

UtilityInteractive Inverter

AC Monitoring
(V, I, P, PF)Meteorology
AC Disconnect • Module Temp • Ambient Temp • Irradiance

Network

Utility Grid Load
NATIONAL RENEWABLE ENERGY LABORATORY

Data Acquisition System
6

IEC 61724 “Photovoltaic System Performance Monitoring – Guidelines for measurement data exchange and analysis”

Total Irradiance –
– – – –

Measured in plane of array Uncertainty including including Instrumentation < 5%...