A $175 million solar-powered mega-greenhouse facility growing tomatoes which is backed by private equity firm KKR is bringing the most certainty of a string of projects aiming to harness the 300 days of sunshine each year in the hard-hit Port Augusta region in northern South Australia.

The sunshine has also attracted two rival $1 billion-plus proposals to build solar energy power plants near Port Augusta, one of the three regional towns which make up the Iron Triangle which also include Port Pirie, and Whyalla, which faces a possible closure of its steelworks after the collapse of Arrium.

The Sundrop Farms project backed by private equity firm KKR growing 16,000 tonnes of tomatoes for Coles each year is the surest bet among the raft of solar projects near Port Augusta. Credit:iStock

The latest proposal is a $1.2 billion solar-thermal power station being proposed by Solastor, a renewable energy firm chaired by former Liberal Party leader John Hewson. A separate project backed by United States company SolarReserve outlined plans last year to build a $1 billion solar plant using slightly different molten salt technology in its plant, which also harnesses the power of the sun.

The Sundrop Farms tomatoes project is in the final stages of construction after a major expansion which increased the size of the greenhouse facility by 100 times after supermarket giant Coles agreed to a 10-year contract to take 16,000 tonnes of tomatoes annually, with KKR ploughing $100 million into the project. A Coles spokeswoman said on Tuesday that Sundrop Farms was dispatching its first deliveries of tomatoes to Coles this week, and they will be supplied to Coles outlets in Victoria, NSW and South Australia.