Backstory: Recently at an event, I left for lunch and took a coffee to go. I finished the coffee rather quickly and couldn't find an empty recycling can to deposit my cup. I ended up carrying it around for 10 minutes. The local sanitation department was not prepared for the event, every trashcan and recycling can were overflowing.
The Idea: A solar powered trash and recycling can that also has a compactor.
Deep Dive: You could build a row of trash and recycling (plastic, paper and cans) together that are all solar powered. These units would have a built in compactor to compress the trash. Given the units have solar power they could hook up to a central website, alerting the sanitation department when the cans need to be emptied.
Validation: Just walk around at the next convention you attend and see the multiple overflowing trashcans. Have you ever noticed this?
Monetization: You would be saving the community time and money, sanitation workers would spend less time visiting trashcans and they would only visit those that need to be emptied. You would have to figure out the cost/time savings and the raw cost of goods to determine the viability of the product. Another option, since there is power, is to have the side of the wall of cans be a LCD screen with scrolling advertisements.