Solar is REALLY CHEAP. And provided you keep existing central European gas heating infrastructure around for a while, you can basically just wait out the really good energy storage by using existing caverns you pre-fill with methane to keep your people from freezing. If you're not curtailing a substantial fraction of PV yield (yearly) in central Europe that's a sign there way not enough capacity yet.

Built facades and roofs out of glass-glass PV laminate. We have the technology from glass roofs/facades; you just add glass-catching-mesh/insulation below because you can't use the insulated multi-pane window glass construction with safety lamination and solar cells all three together.