By Lena Babaeva Coradini

As evidenced in blog entries like this, there is a lot going on in politics to sway the United States from buying Chinese solar power products.

High government support in China, however, does entice American companies. For example, Evergreen Solar, a solar panel maker, is moving production to China.  Evergreen Solar emerged in the last three years as third-largest maker of solar panels in the U.S., partially due to the millions of dollars of assistance from the government of Massachusetts:

But now the company is closing its main American factory, laying off the 800 workers by the end of March and shifting production to a joint venture with a Chinese company in central China. Evergreen cited the much higher government support available in China.

The factory closing in Devens, Mass., which Evergreen announced earlier this week, has set off political recriminations and finger-pointing in Massachusetts. And it comes just as President Hu Jintao of China is scheduled for a state visit next week to Washington, where the agenda is likely to include tensions between the United States and China over trade and energy policy.

The Obama administration has been investigating whether China has violated the free trade rules of the World Trade Organization with its extensive subsidies to the manufacturers of solar panels and other clean energy products.

While a few types of government subsidies are permitted under international trade agreements, they are not supposed to give special advantages to exports — something that China’s critics accuse it of doing. The Chinese government has strongly denied that any of its clean energy policies have violated W.T.O. rules.

Although solar energy still accounts for only a tiny fraction of American power production, declining prices and concerns about global warming give solar power a prominent place in United States plans for a clean energy future — even if critics say the federal government is still not doing enough to foster its adoption.

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Evergreen, in announcing its move to China, was unusually candid about its motives. Michael El-Hillow, the chief executive, said in a statement that his company had decided to close the Massachusetts factory in response to plunging prices for solar panels. World prices have fallen as much as two-thirds in the last three years — including a drop of 10 percent during last year’s fourth quarter alone.

Chinese manufacturers, Mr. El-Hillow said in the statement, have been able to push prices down sharply because they receive considerable help from the Chinese government and state-owned banks, and because manufacturing costs are generally lower in China.

“While the United States and other Western industrial economies are beneficiaries of rapidly declining installation costs of solar energy, we expect the United States will continue to be at a disadvantage from a manufacturing standpoint,” he said.

Even though Evergreen opened its Devens plant, with all new equipment, only in 2008, it began talks with Chinese companies in early 2009. In September 2010, the company opened its factory in Wuhan, China, and will now rely on that operation.

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Chinese solar panel manufacturers accounted for slightly over half the world’s production last year. Their share of the American market has grown nearly sixfold in the last two years, to 23 percent in 2010 and is still rising fast, according to GTM Research, a renewable energy market analysis firm in Cambridge, Mass.

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Evergreen did not try to go through the long, costly process of obtaining a federal loan because of what it described last summer as signals from the department that its technology was too far along and not in need of research and development assistance. The Energy Department has a policy of not commenting on companies that do not apply.

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In a telephone interview in August, Mr. El-Hillow said that he was desperate to avoid layoffs at the Devens factory. But he said Chinese state-owned banks and municipal governments were offering unbeatable assistance to Chinese solar panel companies.

Factory labor is cheap in China, where monthly wages average less than $300. That compares to a statewide average of more than $5,400 a month for Massachusetts factory workers. But labor is a tiny share of the cost of running a high-tech solar panel factory, Mr. El-Hillow said. China’s real advantage lies in the ability of solar panel companies to form partnerships with local governments and then obtain loans at very low interest rates from state-owned banks.

Evergreen is not the only solar panel manufacturer to struggle in the United States. Solyndra, which has received federal loan guarantee and was visited by the President, announced in November that it was shutting one of its two American plants.