The European Commission has opened an in-depth investigation to assess whether an arbitral award ordering Bulgaria to compensate ACF Renewable Energy Limited for changes to Bulgaria’s renewable electricity support scheme complies with European Union State aid rules. The Commission’s preliminary view is that the award and its implementation would constitute State aid under Article 107(1) of the Treaty on the Functioning of the European Union (TFEU) that is incompatible with the internal market. Bulgaria introduced a renewables support scheme in 2011 and modified it in 2013, 2014 and 2015, with the scheme as in place in March 2016 notified to and approved by the Commission in August 2016. ACF, a Malta-established company that acquired a Bulgarian solar photovoltaic plant in 2012, brought arbitration proceedings seeking compensation for support it claimed it would have received absent the changes; an award dated 5 January 2024 found Bulgaria in breach of the Energy Charter Treaty and ordered compensation of EUR 61.04 million plus interest, which Bulgaria has notified to the Commission but has not paid. The Commission will examine the measure’s compatibility with the internal market, including whether the intra-EU award and its implementation breach EU Treaties provisions on the Court of Justice of the European Union’s jurisdiction, notably Article 19(1) of the Treaty on European Union and Articles 267 and 344 TFEU. Opening the in-depth investigation allows Bulgaria and interested third parties to submit comments and does not prejudge the outcome; a non-confidential version of the decision is to be published in the State aid register under case SA.114457 once confidentiality issues are resolved.