Open Circuit Voltage Test. The open circuit voltage test provides a simple method to determine that a string is properly connected and that all strings are producing the appropriate level of voltage. This test should be done under stable sky conditions.
a) Measure string Voc at the combiner box for all strings at the combiner box.
b) Measure average module temperature.
c) Measure plane of array irradiance.
d) Calculate the expected Voc for each measurement using the following formula: Where n is the number of modules in series, Voc, expected is the Expected Open Circuit Voltage, Voc,ref is the open circuit voltage of a single module as specified on the module data sheet, b is the module Voc temperature coefficient measured in [1/°C] as listed on the module data sheet, and Tmeasured is the measured module temperature during the time of Voc measurement.
e) Compare the expected Voc to the measured Voc for every string using the following equation (Voc measured – Voc expected) / Voc expected. This value shall be 95% to 105% for the string to pass. If the string does not pass, the string connectivity shall be inspected; all modules in the string shall be inspected for visible damage, and j-box tabs shall be re-soldered as required. Defective modules shall be replaced.
Open Circuit Voltage Test. The open circuit voltage test provides a simple method to determine that a string is properly connected and that all strings are producing the appropriate level of voltage. This test should be done under stable sky conditions.
a) Measure string Voc/Isc at the combiner box for all strings at the combiner box.
b) Measure average module temperature.
c) Measure plane of array irradiance.
d) Contractor shall test, record, and analyze all collected data. Data analysis shall include, at minimum, a calculation that shows the relative Voc, Imp & Pmax values for each string at STC.
e) Contractor shall submit the test data, analysis, and results within one (1) week after testing has been completed. All calculations shall be provided in Excel format with calculation formulas shown.
f) A written statement shall be provided with each data submission that states the tested string values (Voc, Isc, Vmp, Imp, Pmax) are within manufacturer tolerances at STC.
g) If any string is abnormal, or not performing as expected, a detailed investigation and root cause analysis shall take place. All analysis results and corrections made shall be documented in the data submission and report summary including all abnormalities and/or problematic strings.
Open Circuit Voltage Test. Purpose: Open Circuit Voltage Testing provides a simple method to determine that all strings are properly connected (module and string polarity) and that all PV modules are producing an appropriate voltage level. Scope: All strings Party: Contractor technical personnel Equipment/ Materials: rubber insulating gloves voltmeter with an accuracy of at least 1 percent of reading fuse puller infrared thermometer or thermocouple PV specification for Voc as a function of temperature jumper wire Conditions: This test should be conducted under full sun (>500 W-‐m-‐2) and stable sky conditions, generally between the hours of 10:00am and 2:00pm.
Open Circuit Voltage Test. Demonstrate that all strings are properly connected and that all PV modules are producing an appropriate voltage level.
Open Circuit Voltage Test. The string Isc should meet the criteria defined below: The measured current should be within 5% of the expected Isc calculated using equation below: I = n ⋅ I ⋅ G ⋅ 0.95 sc,expected sc, REF G REF (1) where n = number of modules in parallel in test segment Isc, expected = expected short-circuit current of the test segment, A Isc, REF = module short-circuit current at some specified reference conditions, A G = measured plane of array irradiance, X-x-2 GREF = irradiance at some specified reference conditions, X-x-2 0.95 = factor to account for soiling, misalignment, and other factors. All I-V curves should be similar in shape (other than differences due to changes in irradiance or temperature). This test will not be required if normal light conditions are not available during the Acceptance Test Period. Comments: If results show anomalies, including fill factor, voltages, or currents outside expected limits or humps on the curve, then investigate for bypass diode conduction, out-of-tolerance module performance, or other possible problems. Rectify any flaws and re-test.
