Home Electricity

Why I built it

The bill arrives once every two months and it is always a surprise. Nothing about that is a mystery — the data was already there, in the Home Assistant sensors I run at home. It just needed putting somewhere I would actually look at it.

The problem

Consumption you cannot see is consumption you cannot reason about. Is this month high because of the air conditioning, or because something is running when it should not be? The ΔΕΗ bill tells you the total two months late, with no way to attribute any of it.

What it does

Whole-house electricity consumption and cost, read continuously from the Home Assistant sensors, correlated against the ΔΕΗ bill so the two numbers can be looked at together. The point is that the bill stops being the only measurement and starts being the check.

Where it is now

Running daily. It has its own guard against the failure mode I caused myself: restarting Home Assistant makes every reading fail at once, and the first version raised an alarm every time I updated. It now stays quiet for a single failure and speaks up only when failures repeat — because a guard that cries wolf on every update is worse than no guard at all.

Who it might interest

Anyone with Home Assistant, a smart meter or whole-house monitoring, and a bill they would like to argue with using evidence. This one is deeply tied to my own setup, so it is more an approach worth copying than a product to install.