[WaxProlix]

It might not be a solution on its own, but you can get a little ways with compressed air energy storage (CAES). There's a bit of discussion on how it can scale up and down to various sizes of installation around the internet[1] but I don't know how much actual storage you get in terms of kilowatt hours.

But used as a part of a more robust system, I think there's promise here. The other type of low-chemical physical potential energy storage that gets some attention nowadays is pumping water to a higher location, only to let it out via a hydro generator later. Not sure how that scales into winter though. (actually air tanks might lose a certain amount of pressure to cold as well; perhaps buried tanks would work better, so that the ambient temp is cooler?)

It's fun to apply this pattern to other types of gravity-based energy. Maybe take excess in the summer and use it to ratchet your water tower up higher, or roll a large boulder up a hill? Or force two magnets really close together :p

1 https://www.resilience.org/stories/2018-05-18/ditch-the-batt...

[hashtag-til]

Regarding water pump solution, it is used in the UK as mitigation for the "TV Pickup phenomenon"

See https://en.wikipedia.org/wiki/TV_pickup