If the country with the subsidies fails to remove them, other countries can retaliate by imposing steep tariffs on imports from that country. But multinational companies and trade associations in the clean energy business, as in many other industries, have been wary of filing trade cases, fearing Chinese officials’ reputation for retaliating against joint ventures in their country and potentially denying market access to any company that takes sides against China.

W.T.O. rules allow countries to subsidize goods and services in their home markets, as long as those subsidies do not discriminate against imports. But the rules prohibit export subsidies, to prevent governments from trying to help their companies gain in world markets.

The W.T.O. also requires countries to declare all national, state and local subsidies every two years, so that if one country’s exports surge suspiciously, other countries’ trade officials can easily check to see if that product is being subsidized.

But China has virtually ignored the requirement since joining the W.T.O. Contending that it is still a developing country struggling to understand its commitments, China has filed just one list of subsidies, which were in place between 2001 and 2004. And that one list covered only central government policies while omitting local or provincial subsidies.

The Chinese mission to the W.T.O., which is part of China’s commerce ministry, would not comment for this article. After reading questions The New York Times submitted by fax last week, mission officials declined to respond, saying that any comments might affect China’s standing in other trade disputes.

Sunzone and other Chinese clean energy companies also benefit from the fact that the government spends $1 billion a day intervening in the currency markets so that Chinese exports become more affordable in foreign markets. Systematic intervention in currency markets to obtain an advantage in trade violates the rules of the International Monetary Fund, of which China is a member, although the I.M.F. has little power to punish violators.

Chinese wind and solar power manufacturers further benefit from the government’s imposition of sharp reductions this summer in exports of raw materials, known as rare earths, that are crucial for solar panels and wind turbines. China mines almost all of the world’s rare earths. W.T.O. rules ban most export restrictions.