With AU electricity prices where they are, the fastest ROI in the smart home is knowing where the kilowatts go.
Level 1: plug-level ($35)
An Energy-monitoring plug on any suspect appliance. We measured a lounge heater at 2.26 kw — about 68c/hour, $2–3.50/day in winter. One measurement changed how that house heats.
Level 2: switchboard ($90 + electrician)
A Shelly em with a clamp on the mains reads the whole house live. Home Assistant's energy dashboard turns it into daily curves, and the "what is idling at 400w at 3am" investigation pays for the hardware.
Level 3: per-circuit
Multiple clamps split lighting, aircon and the garage. This is gold-package territory — see Installs.
The local-first part
Every reading stays in your house. No energy startup gets your consumption profile, no subscription gates your own data, and the history survives any company's funding round. Energy watch kit →
Skip the shopping list: the Energy Watch Kit bundles the tested gear from this guide — cheaper than buying the parts separately.