The burgeoning strength of the US solar energy market has been again underlined after SunEdison confirmed that it has secured $161m in funding, Suntech continued its international expansion drive and Evergreen Solar announced $1bn of new orders for its solar panels.

Solar energy services specialist SunEdison announced last week that it had closed $131m private equity funding round and secured $30m of debt financing with new and existing investors over the last six months. The company – which is working on two of the largest solar farms in North America in the form of a planned 16MW facility in North Carolina and a 19MW farm in Ontario – said that the cash had been designated to support operational activities as it continues its rapid expansion.

The move comes as global solar giant Suntech Power announced that it has shelled out $98.9m to acquire a minority stake in Chinese photovoltaic cell manufacturer Shunda Holdings. Under the terms of the deal, the two companies have also signed a 13-year supply deal that will see Shunda supply Suntech with seven gigawatts of silicon wafers between 2008 and 2020.

Suntech Chairman and CEO, Dr. Zhengrong Shi, said the deal would provide the company with secure supplies of silicon wafer, enhancing its long term cost competitiveness. "The relatively small quantities of silicon wafers to be supplied in 2008 from Shunda will replace some of our higher-priced spot market silicon, and will make an important contribution towards the completion of our 2008 production target of 530MW," he added. "With this long-term agreement, we are able to increase our silicon secured for 2009 by 50MW to 800MW of silicon with an average cost more than 20 per cent below our average cost of silicon in 2007."

The deal follows a similar move by Suntech earlier this month, which saw it agree to pay up to $100m for a minority stake in Russian polysilicon producer Nitol.

Meanwhile, US-based solar panel manufacturer Evergreen Solar further highlighted booming demand for the technology, announcing that it has secured two deals with up to $1bn. The company said that it had signed a $750m supply agreement with German-based solar farm operator Ralos Vertriebs, a deal it said followed hot-on-the-heels of a $250m agreement with a US installer.

The company said that in addition to these two new orders it already has a further six customer contracts in place, giving it a current order backlog of over $1.8bn.

Richard M. Feldt, Evergreen Solar's president and chief executive officer, said that the company's growth was being driven in large part by the cost competitiveness of its thin film solar cell technology. "We offer our customers a long-term value proposition because our string ribbon technology consumes less than half of the polysilicon as compared to the industry average, which enables us to provide a unique combination of cost and cell conversion efficiency," he said.