Click the link below to read the article at Solar Power World:
https://www.solarpowerworldonline.com/2019/12/mppt-how-energy-harvest-changes-as-solar-projects-age/
Solar Power World Article: How Does Maximum Power Point Tracking Work for Solar?
Article appearing in Solar Power World in December 2019 discussing how MPPT works and how yield can be improved in older PV plants