We’re continually unimpressed by battery performance in general, but particularly during winter. Compressed air storage is an interesting concept (Bill Mollison was also obsessed with it):
Compressing air makes a lot of heat. Lifting liquid seems to be a much more efficient option.
If the trees sway in the wind a lot up there when it’s not sunny, a car alternator with a big flywheel on it could be spun by a rope hooked to a tree top. It would just need a one way clutch on the input and a return spring to retract the cable when the tree sways back. This will make a constant 14v 40A when the wind is blowing. I want to use an array of water jugs as the flywheel when I build one.
I like the idea that the heat and cold from the process can be harvested. This definitely increases the efficiency. The same would apply to a hydraulic system though, which is much more energy efficient both in its manufacturing process and in use. High pressure stuff is hard to make but something as simple as the flushing of a toilet would probably run the lights in a bathroom for the amount of time that they’re necessary.