Commission Decision (EU) 2017/1797 of 23 May 2017 on the aid schemes SA.42393 (2016/C) (ex 2015/N) implemented by Germany for certain end-consumers (reduced CHP surcharge) and SA.47887 (2017/N) which Germany is planning to implement in order to extend the CHP support scheme as regards CHP installations used in closed networks (notified under document C(2017) 3400)