A reader asked for more detail about the reference spectrum, which was published by the American Society for Testing and Materials (ASTM). It's called ASTMG G-173-03, and is derived from the SMARTS v. 2.9 radiative transfer model. It represents a typical mean solar spectrum at noon for the contiguous USA. It’s calculated for 1.5 air masses, but the plane is tilted by 37 degrees so that it’s parallel to one at the equator at noon. The the power available from this spectrum (e.g., for solar photovoltaic systems) from this spectrum is 1 kWm-2. For more details, see https://www.nrel.gov/grid/solar-resource/spectra-am1.5.html.
A reader asked for more detail about the reference spectrum, which was published by the American Society for Testing and Materials (ASTM). It's called ASTMG G-173-03, and is derived from the SMARTS v. 2.9 radiative transfer model. It represents a typical mean solar spectrum at noon for the contiguous USA. It’s calculated for 1.5 air masses, but the plane is tilted by 37 degrees so that it’s parallel to one at the equator at noon. The the power available from this spectrum (e.g., for solar photovoltaic systems) from this spectrum is 1 kWm-2. For more details, see https://www.nrel.gov/grid/solar-resource/spectra-am1.5.html.