Terms defined in this section are relevant to PV module testing. Terms defined in PV-1 and PV-2 are incorporated by reference

1. Air Mass (AM): A dimensionless quantity equal to the ratio of (1) the actual path length of solar radiation through the atmosphere to (2)the vertical path length through the atmosphere at sea level. At sea level, for all but very large zenith angles z, AM = sec z (UL 1703).
   
   
2. AM 1.5 Standard Reference Spectrum: The solar spectral irradiance distribution (diffuse and direct) incident at sea level on a sun-facing 37 degree tilted surface from horizontal. The atmospheric conditions for AM 1.5 are: precipitable water vapor 14.2 mm, total ozone 3.4 mm, turbidity (base e, l=0.5 mm) 0.27 (ASTM E 892).
   
   
3. I-V Data: The relationship between current and voltage of a photovoltaic device in the power-producing quadrant, as a set of ordered pairs of current and voltage readings in a table, or as a curve plotted in a suitable coordinate system (i.e., Cartesian) (ASTM E 1036).
   
   
4. Maximum Power (Pmp): The point on the current-voltage (I-V) curve of a module under illumination, where the product of current and voltage is maximum. For the purpose of this document, "rated" power is defined as Pmp at STC (UL 1703).
   
   
5. PV Module (flat-plate): The smallest environmentally protected, essentially planar assembly of solar cells and ancillary parts, such as interconnections, terminals, (and protective devices such as bypass diodes) intended to generate dc