I was inspired by several DIY projects. The ESP8266 WiFi 802.11 b/g/n Module is a self contained SOC with integrated TCP/IP protocol stack that can give any microcontroller access to your WiFi network. The ESP8266[…]
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.