UL-61215:2012 pdf free download – STANDARD FOR SAFETY Crystalline Silicon Terrestrial Photovoltaic (PV) Modules – Design Qualification and Type Approval.
The second. called “the reference-plate method”, is faster but is applicable only to PV modules of the type which respond to changes of ambient temperature (within restricted ranges of wind speed and irradiance) in the same way as the reference plates used in the measurement. Crystalline silicon modules with a glass front and plastic back are in this category. The reference plates are calibrated using the same procedure as in the primary method.
10.5.3 Primary method
10.5.3.1 Principle
This method is based on gathering actual measured cell temperature data under a range of environmental conditions including the SRE. The data are presented in a way that allows accurate and repeatable interpolation of the NOCT.
The temperature of the solar cell junction (Ta) is primarily a function of the ambient temperature (Tamb). the average wind speed (V) and the total solar irradiance (G) incident on the active surface of the module. The temperature difference (T — Taflib) is largely independent of the ambient temperature and is essentially linearly proportional to the irradiance at levels above 400 Wm2. The procedure calls for plotting (T — Tamb) against G for a period when wind conditions are favorable. A preliminary NOCT value is then determined by adding 20 00 to the value of (T — Tamb) interpolated at the SRE irradiance of 800 Wm2. Finally, a correction factor, dependent on the average temperature and wind speed during the test period, is added to the preliminary NOCT to correct it to 20 00 and 1 ms1.
10.5.3.2 Apparatus
The following apparatus is required:
a) an open rack to support the test module(s) and pyranometer in the specitied manner see 1u.5.J). The rack shall be designed to minimize heat conduction from the modules and to interfere as little as possible with the free radiation of heat from their front and back surfaces:
NOTE In the case of modules not designed for open-rack mounting. the test module(s) should be mounted as recommended by the manufacturer.
b) a pyranometer, mounted in the plane of the module(s) and within 0,3 m of the test array:
c) instruments to measure wind speed down to 0,25 ms1 and wind direction, installed approximately 0.7 m above the top of the module(s) and 1 .2 m to the east or west:
d) an ambient temperature sensor, with a time constant equal to or less than that of the module(s), installed in a shaded enclosure with good ventilation near the wind sensors;
e) cell temperature sensors, attached by solder or thermally conductive adhesive to the backs of two solar cells near the middle of each test module, or other equipment necessary for lEG-approved measurement of cell temperature;
f) a data acquisition system with temperature measurement accuracy of ±1 O to record the following parameters within an interval of no more than 5 5:
— irradiance.
— ambient temperature,
— cell temperature.
— wind speed,
— wind direction.
10.5.3.3 Test module mounting
Tilt angle: the test module(s) shall be positioned so that it (they) is (are) tilted at 450 5° to the horizontal with the front side pointed toward the equator.
Height: the bottom edge of the test module(s) shall be 0,6 m or more above the local horizontal plane or ground level.
Configuration: to simulate the thermal boundary conditions of modules installed in an array, the test module(s) shall be mounted within a planar surface that extends at least 0,6 m beyond the module(s) in all directions. For modules designed for free-standing, open-back installations, black aluminum plates or other modules of the same design shall be used to fill out the remaining open area of the planar surface.