I recently bought and installed this really cool open-source “Dabbler” ESP32-based MEP interface module that transmits real-time multi-phase data from my Echelon power meter to Home Assistant every 5 seconds.

I bought it second-hand for $29, so it was still more expensive than using a photodiode and a basic ESP32 with Home Assistant glow, but I was drawn to the MEP interface because it provides more detailed information, is more discreet and receives power from the power meter itself (no external power source needed).

It can be integrated into Home Assistant via MQTT (most reliable) or you can simply install the HACS integration. (An ESPHome-based version would of course be even cooler but does not exist yet).

New Dabbler MEP modules can be bought here (not sponsored): https://ustepper.com/shop/home/26-esp32-c3-dabbler-mep-interface.html

The Dabbler project on GitHub: https://github.com/DabblerDK

HACS integration for Home Assistant: https://github.com/jnxxx/homeassistant-dabblerdk_powermeterreader

How to get MEP key from your local energy company (Different product but same procedure) (Danish): https://shop.watts.dk/netselskaber/

The Dabbler module should be compatible with all NES Echelon 83331-3I and 83331-32 power meters. If your power meter is not compatible, there are other similar projects for other power meters, including Kamstrup. (POW-K+ etc).

The cheapest and perhaps simplest solution is Home Assistant Glow, which is compatible with practically any power meter but does require an external power source: https://github.com/klaasnicolaas/home-assistant-glow

UPDATE: The competing product Watts live now offer local integration via MQTT as well (Danish): https://watts.zendesk.com/hc/da/articles/10271861655580-Brug-Watts-Live-sammen-med-Home-Assistant

I switched to Watts live which has been working completely reliably evet since setting it up. The Dabbler module unfortunately had to be restarted from time to time.