The Government has decided to appeal a High Court ruling which stated its plans to cut solar panel subsidies were "legally flawed".
The Department for Energy and Climate Change says it will lodge an appeal tomorrow, which is the deadline to do so.
However, it is not certain the appeal hearing will happen as the court still has to decide whether to allow it.
The Government wants to halve the feed-in tariff, which pays people to generate electricity, for anyone who installed and registered after 12 December, even though the consultation on the plans ended on 23 December, with the results not expected until later this year.
Pressure group Friends of the Earth and two solar companies, Solarcentury and HomeSun, went to court to test whether the short-notice proposals were lawful.
Mr Justice Mitting said just before Christmas that the Government was "proposing to make an unlawful decision".
Friends of the Earth head of campaigns Andrew Pendleton says: "The Government's illegal cuts to solar tariff rates have near-crippled an industry and threatened thousands of jobs.
"Trying to appeal the High Courtís ruling is an expensive waste of taxpayers' money Ė the court says the Government has no realistic chance of winning, and it will prolong uncertainty among solar companies just when they need reassurance."