The European Commission is threatening to take the Government to court over its controversial decision to cut solar-power subsidies by half.  The commission became the latest party to question the move publicly yesterday, revealing that it had contacted the Government as it investigates the impact of the cut.  G?nther Oettinger, the EU Energy Commissioner, said: "Whenever member states revise their support for support schemes for renewable energy, they need to do so in a manner which does not destabilise the renewable-energy industry or risk undermining their plans to achieve their 2020 targets."  The Government is legally obliged to generate 15 per cent of its energy from renewable sources by 2020.  "Should the UK weaken policies in such a way that it would threaten progress towards their targets, the commission would take a