Arduino Uno WiFi REV2 temperature of pool and solar panel control system + weather station in Osek u Duchcova, Czech Republic. Uses thermocouple type K and MAX 6675 thermocouple module for temperature measurement and BME280 like wether station - air pressure, temperature and humidity. Direct control pool filter pump throw 230V AC relay. Two pots are for setpoint diference of temperature and for hysteresis setpoint settings. The measured data is sent to the Thingspeak cloud. The system also includes a simple web server. Clock synchronized from NTP.
The thermocouples are used only because they were freely available. They are quite inaccurate and the value oscillates very much. To make it more accurate I fit the last 10 values. Most of the code is a compilation from samples and public sources.
The system is in its third year of operation. TTGo is a portable datamonitor that reads back data from thingspeak and displays it on a colour display.