The uncertainty over the fate of the feed-in tariff looks set to continue, after three court of appeal judges failed to reach a conclusion last Friday as to whether or not the government's proposed changes were, as claimed by Friends of the Earth, illegal. Campaigners and Industry bodies hoped that the judges would rule on whether to hear a government appeal against a previous High Court ruling which had branded proposed cuts to the feed-in tariff as illegal, on the grounds that they would come into effect before the end of a the government's official consultation period on the proposed changes.

But the judges failed to reach a verdict. They stated that they hope to make a decision as soon as possible in order to provide the industry with more certainty, whilst declaring that it was "rather optimistic" to think a decision could be reached before the end of this week.

Solar P.V. firms are increasingly desperate for the court and the government to provide clarity on when anticipated cuts to feed-in tariffs will come into effect.

"The stakes have increased massively today," said John Faulks, general counsel of Solarcentury. "The Secretary of State's defence is seriously worrying. He thinks he has the power to do whatever he likes to FITs whenever he likes. And that means no FITs are safe for any technology installed or not at any time.

"We will be awaiting a judgment for at least a week, and hope for the sake of all stakeholders in our renewable energy future – investors, consumers and the general public – that we win this case to secure the robust, secure feed-in tariff we need to drive our low carbon future. DECC have it within their power to remove the uncertainty immediately."

It is still unclear what level of support new installations can expect, or even whether there will be long term assurances regarding tariffs at all – a damaging scenario that has resulted in a month-long hiatus in new installations.

Friends of the Earth, who brought the initial case against the government's consultation alongside a number of solar firms and green consultancies, reiterated its calls for the government to ditch its appeal and lay legislation before parliament that would allow it to cut feed-in tariff incentives in a legal manner from the end of February.

Writing on Twitter in response to the news of delay, head of campaigns at the NGO, Craig Bennett, said: "Chris Huhne could end uncertainty by tabling regs in Parliament to bring FIT down at end Feb in lawful rather than unlawful way."

Gaynor Hartnell, chief executive of the Renewable Energy Association, criticised the "cavalier" manner in which she said DECC has managed the feed-in tariff.

"No one liked the way the government handled this consultation," she said. "Whatever the outcome of the appeal, the court case should ensure that the government thinks twice about acting in such a cavalier manner again."

She also called for lower feed-in tariff rates to be set as quickly as possible to help stabilise the industry. "Having said that, the majority of our members want to draw a line under this affair, look forwards, and get on with installing systems at the new tariff rates," she said.