Good post. I like the concept and its cosmetic design!
It could be also placed at schools for outdoor sports club, school events. Also, many music festivals and rave which often appeals ecology. However, key of success is how to make users profitable with more simple way. "Saving money for future" is sometimes too far to think over for general people.
I would be facing following concerns as a potential user.
Reliability Since I can recoup only 5% of initial investment, I would be curious about life time and warranty. I would pay if I know I could recoup investments within 10 years by repairing it occasionally (but this could be recoupable too).
Cost This makes me hesitate to pay the most. As far as Japan concerned, majority of them are interested in protecting earth, but does not feel it win-win to deteriorate their life. All the more, once cost issue is overcome, demand will decrease drastically!!
Degradation Since the unit is installed in out side for long time, it can not be miserable after used for long time.