Friends of the Earth, one of the parties that brought the original High Court case, understand a final decision may be more than a week away.
The judges presiding over the case advised the parties that while their intention is to conclude the matter as soon as possible, they have reserved their judgement and that it is unlikely that a decision will be handed down by next week.
Reacting to the courts decision to hear the case, the Renewable Energy Associations Gaynor Hartnell said that no one has liked how the government has carried out the FIT review process.
"Whatever the outcome of the appeal, the court case should ensure that the Government thinks twice about acting in such a cavalier manner again. 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."
Recent figures have shown installed photovoltaic capacity in the UK going through the roof in the last two months of 2011, as installers rush to finish jobs before the FIT cuts come into effect.
The Department of Energy and Climate Change, which is bringing the appeal before the court, issued a statement saying that once the court arrives at a decision that they will formulate a policy regarding the FITs. "Once the outcome is known we will consider our options and make an announcement on the way forward to provide clarity to consumers and industry," the statement reads.