It's not necessarily true that if Ukraine generates and sells surplus electricity somewhere, that that electricity can be delivered to any part of Ukraine's grid. It could be that some of the surplus power would just get wasted if it can't be sold abroad or to Donbass or Russia, as it has been.
It isn't actually 'Ukraine' exporting electricity, although every report states it as such. It's DTEK who exports most of the electricity, it's probably DTEK who is controlling the mines in Donbas (they were before the invasion), it is almost certainly DTEK receiving the coal in Mariupol, and it is definitely DTEK responsible for the statements from various ministers. And when I say DTEK, I actually mean Ahkmetov and the people behind him, who we never hear about but who use him like the puppet he has always been.
Since 2004, (and probably before then) those folk been in control of the government, nothing has really changed since then.
Solar, wind, tidal, and any form of renewable energy is the way of the future, smart people need to get together and organise, the time for intelligence is now.