Meanwhile, the world's richest countries pledged to contribute to a fund that would help developing countries deal with climate disasters.
Since construction began in 2015, Bhadla Solar Park has slowly grown to cover an enormous 5,700-hectare desert site with solar panels.
Sustainable financeThe park was built in four phases, with each field of solar panels larger than the last.
"Transmission lines take about ten times as long to build as it takes to put up solar panels," Mukherjee said.
"When you see technology costs dropping, sometimes precipitously like they have with solar panels, then the opportunity to do more just grows and grows."