The law may push the proportion of renewable energy used in China up to 5 per cent of the total power supply by 2010 and 10 per cent by 2020, said Feng Zhijun, vice-chairman of the Environmental and Resources Conservation Committee of the National People's Congress (NPC) on Saturday. The NPC is the country's top legislature.

Feng said currently the proportion stands at 2 to 3 per cent.

Feng attended a ceremony over the weekend in Baoding, Hebei Province, to mark the expansion of the country's only production base of silicon wafers, solar cells and solar modules.

The Tianwei Yingli New Energy Resources Company opened the base last December. It can produce enough silicon wafers and solar cells in one year to produce 6 megawatts of power, and enough solar modules for 50 megawatts.

The company is now spending 400 million yuan (US$48 million) to expand the base. The expansion will allow it to produce enough silicon wafers to pump out 70 megawatts of power, solar sells for up to 50 megawatts and solar modules for 100 megawatts, said Ding Qiang, the company's chairman.

The expansion will put Tianwei Yingli among the top 10 photovoltaic producers in the world, he said.

He Zuoxiu of the Chinese Academy of Sciences said solar energy should be given top priority among renewable energy development.

"The expansion of the base is an important event in the development of solar energy," he said.

He said the potential of solar energy in China is huge.

Within a desert area of 100,000 square kilometres, 2.5 billion kilowatts of power can be generated if 15 per cent of the solar energy there can be transformed. he said.

That is the percentage of solar energy the company's products will be able to transform after the expansion. Deserts in China cover a total area of 854,000 square kilometres.

China's power generation capacity needs to hit 2.5 billion kilowatts by 2050 to meet increasing demand.

He said China's market for renewable energy, especially solar energy, will grow greatly after the law on renewable energy comes out.

Li Ye, an official from the National Development and Reform Commission, said at the ceremony that supplying a certain proportion of clean energy should be made compulsory for power companies.