But Sven Teske, a contributing author to the Intergovernmental Panel on Climate Change (IPCC)'s recent report on renewable energies, also warned that progress could be endangered by market uncertainty over the future of feed-in tariffs.
These tariffs are subsidies allowing fledgling renewable industries to compete with fossil fuels that receive up to 10 times more state aid.
In an exclusive interview, Teske, who is also renewables director at Greenpeace International, told EurActiv that on current trends, he expected Spain, Italy, France and Germany to reach grid parity by 2015.
Attaining parity across the EU as a whole would take "five, maybe six years," he said, "and therefore we urge governments not to change their policy. We are almost there and what we need is a stable feed-in tariff policy".
In 2007, the EU's PV Technology Platform estimated that grid parity would only "apply to most of Europe by 2020". The European Photovoltaic Industry Association made the same prediction.
"Reaching grid parity will depend on the geographical situation, irradiation and the price of electricity," said Eleni Despotou, secretary-general of the European Photovoltaic Industry Association (EPIA).
"We have recently done a study that shows that in Italy we can reach grid parity in two years' time, in Germany in all market segments by 2017, Spain 2016," she told EurActiv.
Stop-and-go policies undermining solar PV sector
But while the solar PV industry's rapid growth has surprised many observers, cuts to national subsidies have also startled the markets, leading some companies to look eastwards for opportunities in emerging markets.
The EU's climate action commissioner, Connie Hedegaard, told EurActiv that EU nations should remember the Commission's 2020 targets for renewables when taking such decisions.
"Take care that you, the member states, are not doing anything retroactively that will just make people fear to invest in this area," she said. "It's in nobody's interests."
"That does not mean that if you've had the feed-in tariff once it can never, ever be changed. But you have to be very cautious and you have to give very, very long warnings."
Stop-and-go policies are exactly the sort that spook investors, said EPIA's Eleni Despotou, citing feed-in tariff cuts in France and Spain as examples.
"Governments may introduce a law [with] something wrong in [it] from the beginning. You may have very generous incentives in order to kick off the market and once the incentive is too generous, that of course creates some speculative bubbles."
"We used to have a leader in 2008 which was Spain and today it is just far behind – it is not a Gigawatt market," said Despotou, criticising Spanish cuts which had a retroactive effect.
Even with long warnings, market uncertainties caused by tariff cuts have apparently led companies such as First Solar to announce major new deals in China and Total to invest in the US.
Teske expected Europe's global market share to drop as a result.
He stressed that solar PV companies should also be allowed to provide as well as produce electricity because at present, utilities could double their overnight backup prices – when the sun is not shining – and so nullify the benefits of any feed-in tariff.
"The main focus should be on allowing all electricity to be fed into the grid at a certain minimum price," he said, "even if it's lower than the market price. You just need something reliable".