Sell a storage system that allows the batteries to be safely and individually stored and integrated. It could estimate the capacity of each battery and house 20 or so. Such a system could probably pay for itself after using it for less than a year. There are certainly going to be guaranteed minimum capacities that such a system could promise, it doesn't need to be perfect. If enough people invest in such power storage systems, you don't need to have a single system work 100% of the time, just like you don't need every wind turbine to work 100% of the time.
There is some scope for winged humans, and hypothetically some capacity to exercise it. Nature did not explore this route. The opportunity cost of exploratory settling into a non-preferred niche usually outweighs the benefits of that exploration simply due to the scarcity of available resources to buffer against the opportunity cost.
I don't understand the recent push to ascribe consciousness to trees. An anesthetized human being has many more allostatic and homeostasic mechanisms than a tree, and yet we don't ascribe consciousness to anesthetized humans...