This project introduced me to Arduino, when in early 2013 I was looking around for home electricity monitoring systems. I found quite a few off the shelf products available, but they all seemed limited in flexibility, and expensive too. That’s how I discovered the excellent OpenEneryMonitoring project, a lively open source platform for energy monitoring. This was exactly what I was looking for, although it went far beyond my hardware and software knowledge. It has introduced me to the wonderful world of Arduino.
Over the years I have expanded this system to included temperature and humidity monitoring, and solar powered sensors, as in the overview graph below.

This setup allows me to store my data on a cloud server accessible from anywhere, and keep an eye on e.g. indoor humidity levels. I will add more sensors, probably based on recently made available cheap wifi chips rather than the original RF system above.

This project is documented in detail on a separate blog: Lantau kilowatt counter.