My new project consists of HW with cost under 20€. It is able to accurately measure electric power consumption and sends data via WiFi. Great source of knowledge is openenergymonitor.org which includes also Arduino library.
ESP8266 WiFiManager EEPROM My next addition to previous projects battery-wifi-iot-temp-hum-soil-moisture-sensors and battery-powered-esp8266-iot-logger is to make wifi configuration smooth and fast.
You can find several breadboard adapters for ESP8266 WiFi module or nRF24L01+ RF transceiver and also several DIY manuals how to create your own, but I decided to use my new WiFi WSP8266 and NRD24L01 as soon[…]