Logging my solar house with IoT, Arduinos, ESP8266's and lots of sensors. We are off-grid and use solar panels to charge batteries. When we have sufficient sun and the batteries are charged we switch on the pool filter and hot tub using MQTT.
Weather Station in Germany, used to control garden lamps and watering system with all the data. No water if there is too much light or too much wind, and so on...
Very useable statistics :)
Schöne Wetterstation im Esten von DE!
more features will