Stima: pay-as-you-go electricity
Pay on M-Pesa and the lights come on. No 20-digit token.
- Status
- PrototypeWorking prototype with demo video; v2 deployed on shared hosting
- Period
- Dec 2025 → 2026
- Role
- Hardware, firmware and backend
- Brand
- Tuchopini
An M-Pesa STK Push payment hits a server callback, is logged to a local database, and an Arduino/ESP8266 relay switches power on for the paid duration at KES 1 per 10 seconds. Version 2 re-architected the device to poll the server every three seconds so it works from any Wi-Fi with no port forwarding, and deployed the backend to shared hosting so it demos anywhere.
The problem
Prepaid electricity in Kenya makes you pay, wait for a 20-digit token by SMS, walk to the meter and type it in. People mistype it or lose the SMS.
What we built
Payment applies credit automatically. The token step disappears.
What it does
- M-Pesa Daraja STK Push and callback
- Reverse-polling ESP8266 firmware
- Relay control timed to the amount paid
- Deployable on shared hosting
Every part of the chain is standard technology. The engineering is designing for the weakest link: the GSM or Wi-Fi at the meter's wall, not the data centre.
Watch
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