Manoj Kumar Upadhyay has been experimenting in green energy for decades, but it’s his early bet on solar power that’s driven the founder into the ranks of the world’s richest.

The 54-year chairman and managing director of ACME Group listed his renewable energy firm, Acme Solar Holdings Ltd. on Wednesday in Mumbai, propelling his and his family’s fortune to about $1.1 billion, according to the Bloomberg Billionaires Index. Most of that comes from the 83.4% stake that he and his wife, Mamta, hold in the firm, which builds and runs solar power plants.

Manoj Upadhyay

Source: Acme Solar Holdings Ltd.

He is one of …