Companies led by SoftBank Group Corp. and Taiwan's Foxconn Technology Co. Ltd. are bringing India some of the cheapest solar power in the world, helping Prime Minister Narendra Modi reach his ambitious clean-energy goals.

In two auctions this week for renewable energy power-purchase contracts, bids from companies to supply clean electricity slid to as little as 3.8 cents a kilowatt-hour. The record is sharply below the previous bids of around 5 cents and within striking distance of the lowest recorded bids in the United Arab Emirates and Chile, according to Bloomberg New Energy Finance.

India is already among the most competitive generators of solar power after establishing auctions for capacity that drew capital both from Western utilities and from development banks anxious to help Modi clean up his country's notorious smog. Each new auction over the past two years has helped India's renewable energy generators close the gap with the lowest cost fuels such as natural gas and coal, said Shantanu Jaiswal, an analyst for BNEF in New Delhi.