Pay as you go solar. Payment done through mobile SMS banking networks like mPesa. Each unit has a SIM card to receive commands.
Considering solar panel costs are < $500 kW and Chinese lithium iron phosphate batteries are < $400/kWh, a financially sustainable business model is entirely possible.
Mobile operators are the ideal vendors but lack imagination. That's where you come in.
We're doing that with the Shared Solar project (http://sharedsolar.org/). Some parts of the project were spun off into a for-profit business by former lab members. Interestingly, although SMS payments were built into the system, no one used them as it was easier to just walk down the street and buy credits with cash.
Considering solar panel costs are < $500 kW and Chinese lithium iron phosphate batteries are < $400/kWh, a financially sustainable business model is entirely possible.
Mobile operators are the ideal vendors but lack imagination. That's where you come in.