For quite some time, some pioneers found a use for Renewables and improved efficiency. The ROI was (marginally) viable to them. Over time technology got cheaper

For quite some time, some pioneers found a use for Renewables and improved efficiency. The ROI was (marginally) viable to them. Over time technology got cheaper/more efficient (gradual improvements to ROI), and slowly more and more people started to adopt renewables, better insulation, heat pumps, etc. Recently, energy prices in Europe have (roughly) doubled [1]. And suddenly -by comparison- that same ROI starts to look very interesting to a lot more people. [1] (YMMV, check your local energy spot prices for actual numbers)