US-based solar panel producer First Solar has this week announced a four-fold increase in third quarter earnings - the latest in a line of alternative energy firms to post bumper results.

The company, which makes non-silicon 'thin film' panels to capture energy from the sun, said revenues shot to $159m for the three months to the end of September - up from $40.8m in the same period last year and $77.2m in the June quarter.

It said it had benefited from growing demand for its products from companies - particularly in Europe - looking for cost-effective and eco-friendly alternatives to electricity.

"We successfully completed the ramp of our German production facility well ahead of schedule, which afforded us with highly leveraged growth during the quarter and provided our customers with additional production volumes in a continued robust demand environment," said chief executive Mike Ahearn.

The company is expected to build on the strong result in the fourth quarter, having recently signed five contracts with European utility firms for its solar modules and a supply agreement with Babcock & Brown worth $1bn by 2012.

Popularity is being buoyed by European Union incentives for companies that invest in alternative resources as part of its strategy for ensuring 20 per cent of all energy used comes from renewable sources by 2020.

The results come just days after Denmark-based wind turbine manufacturer Vestas posted a 27 per cent rise in its own third quarter revenue to €1.15bn, with full-year 2008 revenue expected to jump 25 per cent to €5.7bn. The company also confirmed it has recently signed deals with the US and France for more wind turbines and predicted that despite continuing issues with the supply of parts it expects revenue for 2008 to grow 25 per cent to €5.7bn.

The latest results underline the strong financial performance currently be ing recorded by the world's leading green energy companies as demand for renewable technologies continues to soar.

Norway's Renewable Energy Corporation - one of the largest solar companies in the world - last month reported a 30 per cent rise in revenues to 1480 Norwegian Krones (£133m) for the same quarter. Meanwhile, China-based Trina Solar's string of new supply deals has pushed its share price up more than 60 per cent in the past few months, and JA Solar Holdings shares have shot up more than 125 per cent.

Experts are predicting solar energy will be the fastest growing alternative energy market in the world over the next 25 years, driven by high oil prices, industrialisation in China and India and financial incentives from world governments.