HONG KONG — The bankruptcies of three American solar power companies in the last month, including Solyndra of California on Wednesday, have left China’s industry with a dominant sales position — almost three-fifths of the world’s production capacity — and rapidly declining costs.

Some American, Japanese and European solar companies still have a technological edge over Chinese rivals, but seldom a cost advantage, according to industry analysts.

Loans at very low rates from state-owned banks in Beijing, cheap or free land from local and provincial governments across China, huge economies of scale and other cost advantages have transformed China from a minor player in the solar power industry just a few years ago into the main producer of an increasingly competitive source of electricity.

“The top-tier Chinese firms are kind of the benchmark now,” said Shayle Kann, a managing director of solar power studies at GTM Research, a renewable energy market analysis firm based in Boston. Pricing of solar equipment is determined by the Chinese industry, he said, “and everyone else prices at a premium or discount to them.”