What are BOL and EOL?
Beginning-of-Life (BOL) means the product’s performance is calculated before exposure to the space environment. BOL values are measured at 28°C, under the AM0 spectrum (solar irradiance spectrum in space), and assuming solar flux of 135mW/cm2. End-of-Life (EOL) is the design point for the end of the mission. For example, if the spacecraft is required to provide power for 15 years in geosynchronous orbit, then the power needed at BOL – to eventually meet the EOL requirement – would be calculated based on the radiation degradation anticipated over the course of the 15 years having been subjected to the radiation fluence for that orbit (solar cell radiation degradation properties can found on the product data sheets) and at the anticipated operating temperature.
