In the mid-1990s, Zhengrong Shi had been a graduate student at Sydney's University of New South Wales and worked on a "solar cell" technology called Crystalline Silicon on Glass (CSG) with a Professor Martin Green and colleagues.

Australia was unable to find the capital to commercially develop this promising technology and apart from a small royalty for the Uni, the local interest in CSG technology was sold to a German company in 2004.

Shi started visiting China regularly from Australia and his friends lobbied him to return to China. Shi acceded and created a company called Suntech Power. Soon afterward, the government of Wuxi, a city on Shanghai's western outskirts with ambitions to become a high-tech center, put up $6 million to finance Suntech, which started with 20 employees, and helped to land $5 million in research grants.

Suntech Power makes photovoltaic solar cells (PV cells) and solar electric systems. Its products are used in residential, commercial, industrial, and utilities, for both on-grid electricity generation and off-grid use, such as lighting for street lamps, telecommunications, and mobile phone networks.

In 2005, Shi's confidence paid off when his Suntech Power Holdings went public on the New York Stock Exchange and investors snapped up shares, turning him into a billionaire. Last year, Shi ranked No.7 on the Forbes magazine list of China's richest tycoons, with a $1.4 billion fortune.

Suntech's 3,500-strong work force at four sites in China produces photovoltaic cells, the delicate, hand-sized black silicon panels that can transform sunlight into electricity.
   
Suntech's key markets are Germany, Japan and Spain, which subsidize renewable energy by requiring utilities to buy solar-generated power and to pay more for it than they would for electricity from oil or gas. China accounted for just 10 percent of Suntech's 2006 sales of $599 million. The equipment is expensive enough that its use in the company's home market is limited to lighthouses, remote military posts and other sites far from power plants.

Suntech Power is now the world's 10th-largest solar cell manufacturer and the leader in China. Major international customers include Aleo Solar, Bihler, Conergy, IBC Solar and SolarWorld AG. Photon International, the trade magazine, ranked Suntech fifth place in capacity and sixth place in production in its annual solar league table.

Shi is part of a generation that left China by the tens of thousands in the drab 1980s to study or work. They are now trickling back, lured by the booming Chinese economy's new opportunities.
   
Shi is the leader of an emerging group of Chinese entrepreneurs who are striking it rich by meeting fast-growing demand in China and abroad for cleaner power. He is also part of a growing group of returnees who are benefiting from government support for technology and new protections for private business. A few, like Shi, have become very wealthy by selling shares in their ventures on foreign stock exchanges.

Shi works 10- to 12-hour days and spends eight months a year on the road in Europe, the United States or China. Shi said he has little time to enjoy his wealth.  "I'm a scientist," Shi said. "My hobby is solving technical problems." But he said that he wants to devote more time to charity work, including an environmental education program that he launched with his wife.