LiFePo4 are now about 50$/kwh, still going down. Plenty of sun in the winter too, just needs to install a little more pv. In fact the worst heat wave is not ideal for photovoltaics, they work better / are more efficient when they are aren’t scorching hot (e.g. often in the summer mornings they produce more than at midday)

In the EU wind is stronger in winter. So you really want both.

Though the graph they show is more promising, with wind having a complementary pattern to solar. If reliable, it would be great.

You can still see a spike in gas around Feb 2025, when wind was weaker and there was still little irradiation.

This is just Germany, but here it holds true: https://www.energy-charts.info/charts/energy/chart.htm?l=en&c=DE&year=-1&stacking=stacked_percent&interval=month&legendItems=0x7vru&month=-1

Spain and Italy have lots of Solar too, idk about the more northern countries, but it seems plausible to me. It doesnt say “majority” and achieving “biggest” isnt all that hard because the total is just split up between so many types of sources.