As Goldman Sachs Group Inc. and billionaire Masayoshi Son lead a swarm of investors exploiting Japan's solar power subsidies, the world's biggest, Sumitomo Corp. is betting on wind.

The lessons of Europe show that those that get in early reap the most benefit before tariffs rates are cut. Of all the renewable energy types available in Japan today the quickest to set up on a utility scale is solar, said Dean Enjo, an analyst with CLSA Asia-Pacific Markets in Tokyo.