This is a great link. The most interesting feature of the solar graph is the amplitude of the seasonal variations. It looks like we typically generating ~100% more solar power in July than December.

If "we need to store solar energy from summer to winter" is indeed a significant issue, maybe you could use the extra power in summertime to make natural gas [1] and then store the gas until you need it in the winter.

[1] https://www.terraformindustries.com/ is a startup working on turning solar power into natural gas