"Irradiance data" refers to information about the amount of energy or light that is received or emitted by a surface. It helps us understand how much energy or light is present in a given area. Full definition
Electricity price estimates are sourced from the Energy Information Administration and solar production estimates are based on irradiance data from NASA. (tesla.com)
NREL, the National Renewable Energy Laboratory, publishes irradiance data in its report Solar Radiation Data Manual for Flat - Plate and Concentrating Collectors. (blog.aurorasolar.com)
The study posits that one of the reasons for less than perfect fit of sunspot and irradiance data with temperature is that the Sun actually works on a 21 year cycle when the sunspot cycle is combined with the cyclical wobble of the Suns motion through space. (climate-skeptic.com)