Characteristics of PV module at standard test condition (STC)

1. The STC means the modules are tested at solar irradiance 1000 W/m^2, cell effective temperature 25 degree celcius and air mass 1.5.
2. Definition of cell, module, string and array:

• Combinations of cells form a module.
• Module connected in series form a string.
• Series and parallel modules form an array.

                                         

• Every PV module has datasheet that describe its electrical properties.
• Example

             

1. The maximum output or peak or rated power of the module (Pmax) = 170 W.
2. The manufacturer tolerance of the output power is +/-3%. So for STP 170S-24/Ab-1. PV module the output power could be between 1.03 x 170 W to 0.97 x 170 W. However, in practice most of the PV modules are having negative percentage of power tolerance. So, during design stage we use negative percentage for worst case scenario.
3. During peak power condition, the voltage and current of the module are Vmp and Imp respectively.
4. During no load condition or open circuit, the voltage of the module is Voc.
5. Short circuit current of the module is Isc.