Last few months we’ve been playing with the ESP8266 WiFi MCU by Espressif. Providing an unbeatable price of $2.5 per module it gives a lot of opportunities in the field of IoT. Moreover, it comes with a package for Arduino IDE, which makes it a perfect candidate for fast prototyping.

The first project we used ESP8266 in was for monitoring a home solar system for hot water including 3 solar collectors, 2 tanks, a mixing pump and a valve for alternative heating of one of the tanks from the home central heating system. The goal was to optimize the control of the whole system, but in order to do that we had to collect operational data so we installed 5 1-Wire temperature sensors connected to the ESP8266 board. We also wrote a sketch that reads the sensors every minute, applies smoothing of the data and stores the readings in a server via MQTT. Server-side we have a simple worker to store the data coming form the controller via MQTT in a time series database and we’ve setup Grafana to visualize that data and analyze it.


All hardware-related costs are less than $100: Server is on DigitalOcean on a $10 per month droplet. Software development – 30 hours total.

Literally we did this for two weekends enjoying getting our hands dirty 😉

This simple solution now works for more than a month and already gave us some ideas about how to optimize the process by modifying the sketch in a way that ensures hot water in the first tank by either mixing the two tanks (solar collectors are heating up tank 2) or turning on the valve when tank 2 does not have enough hot water.

In conclusion, I can say that this fast prototyping using a $2.5 WiFi module will help us to show our prospects the benefits of IoT-based solutions on a small scale, but fast enough, before moving on to a complete turn key solution.