IEC Solar Simulation Requirements for PV Module Qualification Testing

For terrestrial applications, IEC has defined the standard for PV Current-Voltage characteristics testing (IEC 60904-1) and standards for design qualifications for two categories of PV modules; Crystalline Silicon and Thin Film. These two standards, IEC 61215 and IEC 61646 respectively, document the design qualification and type approval process for each of these PV categories. Although testing can be performed using natural sunlight, solar simulation systems are invaluable in their ability to expedite the development and testing of PV modules. In addition to accelerating the testing process, solar simulation systems also provide repeatable test parameters. The following two tables document the process steps incorporated within the IEC standards where solar simulation systems are recommended along with the basic solar simulation classification requirements. Please refer to the complete IEC international standards for full test procedures and requirements.   IEC 60904-1 Measurement of PV Current-Voltage (I-V) Characteristics Test Title Test Conditions Solar Class 4.2 PV Current-Voltage Test See IEC 60904-1; I-V measurement in simulated sunlight; requires Class BBB solar simulator in accordance with IEC 60904-9; test area shall be equal or greater than area under test; see IEC 60904-1 sec 6 and 7 Class BBB or better   IEC 61215 Crystalline Silicon PV Test Title Test Conditions Solar Class    Preconditioning Prior to testing, all modules must be exposed to sunlight (real or simulated) to an irradiation level of 5 kWh/m2 Unspecified; recommended Class CCC or better 10.2 Maximum power determination See IEC 60904-1; I-V measurement in simulated sunlight; requires Class BBB solar simulator in accordance with IEC 60904-9; test area shall be equal or greater than area under test; see IEC 60904-1 sec 6 and 7. Irradiance between 700 W/m2 – 1100 W/m2 ; Temp monitoring +/-1 C; I-V equipment accuracy +/- 0.2% Class BBB or better 10.6 Performance at STC  and NOCT Cell temperature 25C and NOCT Irradiance: STC=1000 and NOCT=800W/m2 with IEC 60904-3 reference solar spectral irradiance distribution Temp monitoring +/-1 C; I-V equipment accuracy +/- 0.2% Class B or better (recommended Class BBB) 10.7 Performance at low irradiance Cell temperature 25C and NOCT Irradiance: 200W/m2 with IEC 60904-3 reference solar spectral irradiance distribution Temp monitoring +/-1 C; I-V equipment accuracy +/- 0.2% Class B or better (recommended Class BBB) 10.9 Hot-spot endurance test Five-hour exposure to 1000W/m2 irradiance in worst case hot-spot condition Radiant source 1: Steady state simulator 700W/m2 Radiant source 2: Steady state simulator 1000W/m2  +/-10% Radiant source 1: Steady state simulator Class BAB or better 10.10 UV preconditioning 15 kWh/m2 total UV irradiation in the wavelength range from 280 nm to 385 nm with 5 kWh/m2 UV irradiation in the wavelength range from 280 nm to 320 nm UV light source uniformity +/-15%; see 10.10.3 for spectral requirements   IEC 61646 Thin Film PV Test Title Test Conditions Solar Class 10.2 Maximum power determination See IEC 60904-1; I-V measurement in simulated sunlight; requires Class BBA solar simulator in accordance with IEC 60904-9; test area shall be equal or greater than area under test; see IEC 60904-1 sec 6 and 7 Irradiance between 700 W/m2 – 1100 W/m2 ; Cell temp between 25-50 C Class BBA or better 10.6 Performance at STC  and NOCT Cell temperature 25C and NOCT Irradiance: STC=1000 and NOCT=800W/m2 with IEC 60904-3 reference solar spectral irradiance distribution Temp monitoring +/-1 C; I-V equipment accuracy +/- 0.2% Class BBB or better 10.7 Performance at low irradiance Cell temperature 25C and NOCT Irradiance: 200W/m2 with IEC 60904-3 reference solar spectral irradiance distribution Temp monitoring +/-1 C; I-V equipment accuracy +/- 0.2% Class BBB or better 10.9 Hot-spot endurance test One hour exposure to 1000W/m2 irradiance in worst case hot-spot condition Module irradiance 800 W/m2 – 1100 W/m2 Steady state simulator Class CCB or better  10.10 UV preconditioning 15 kWh/m2 total UV irradiation in the wavelength range from 280 nm to 400 nm (uniformity +/-15%) with 3-10% irradiation energy in the wavelength range from 280nm to 320nm Module temp 60C +/-5C; temp, measurement accuracy +/-2C Instrumentation to measure UV irradiation 280nm-320nm and 320nm-400nm with uncertainty of +/-15% UV light source no energy below 280nm; see 10.10.3 for spectral requirements 10.19 Light-soaking Light exposure of 800 W/m2 to 1000 W/m2 under resistive load until Pmax is stable within 2 % Class CCC or better