Processing Key I-V Points

The “Key I-V Points” input option provides an alternative to “basic datasheet” parameters as input for the module file generating algorithm. This is a pre-processing step to the core module file generator. This input format is modeled after the IEC-61853-1 test standard, defined by the International Electrotechnical Commission (IEC) as: “requirements for evaluating PV module performance in terms of power (watts) rating over a range of irradiances and temperatures…a second purpose is to provide a full set of characterization parameters for the module under various values of irradiance and temperature”. See the “Inputs” below for more information.

*Important Note: These inputs are intended to be provided for multiple temperature/irradiance conditions (, ).Each set of inputs is represented by a row in the Key I-V Points user interface. The minimum required input is data at STC.

 

Key IV Points Algorithm

  1. The only required row of inputs is for STC conditions. The provided values for maximum power, voltage at maximum power, current at maximum power, short-circuit current, and open-circuit voltage are assumed to be the final “Electrical Characteristics at STC” of the module.

 

  1. If data is provided at multiple temperatures, temperature coefficients will be calculated for Pmp, Voc, and Isc. This is done by performing a linear regression where the x-values are temperature, and the y-values are the respective electrical characteristic at each temperature (and G = 1000 W/m2). The resulting temperature coefficients are calculated in units [%] by dividing the slope of the linear fit by the respective electrical characteristic at STC.

 

  1. For each temperature, if data is provided at multiple irradiances, relative efficiency at each irradiance is calculated from each as in step 4 of the documentation for “Effective Irradiance Response (EIR) Calculation”.