"It's a realistic, acievable goal, based on the current state of the industry and opportunities in the market, but it requires clear political support from governments around the world," Sven Teske, energy expert with environmental group Greenpeace's German branch, said in a statement.

"In particular, the European Commission must ensure that innovative national incentive schemes for solar electricity are not invalidated on competition grounds," he added.

Germany is global number three after Japan and the U.S. in terms of installed capacity of photovolatic technology, which is designed to convert sunlight into electricity.

Its solar sector, which provides less than one percent of the nation's power, depends on government support schemes for renewable energies currently being reviewed by the EC.

The Solar Generation report is published as part of the global Choose Positive Energy campaign.

That campaign asks governments to provide renewable energy - from solar, wind and hydro energy - to two billion of the world's poorest people in the next decade.

The report projects an average photovolatic market growth rate of 30 percent up to 2020 and 15 percent between 2020-2040. The International Energy Agency forecasts that global energy demand will rise to 27,000 TWh in 2020, and 35,000 TWh in 2040.

"If by 2020 global solar output reached 276 TWh, it would replace 75 new coal-fired power stations, saving 664 million tonnes of carbon dioxide emissions," the report said.

By then, the global solar infrastructure would have an investment value of $75 billion a year, it added.