Monitoring electricity usage at the meter

I’d like to know how much energy I’m using because I want to ensure that the baseline load for my activities is reasonable. It’s difficult to correlate the usage when there’s a significant delay in it showing up on PG&E’s website. I haven’t found a great solution, but I’ll probably end up using the Rainforest Automation EMU-2 connected to a Raspberry Pi to send realtime data to a dashboard system like Grafana.

Wireless

PG&E’s electricity meters can use Zigbee to stream data for its customers, but there are just a few certified “HAN” products that are compatible:

• The AzTech in-Home Display costs $150 and seems stuck in 2002.

• The Embertech Emberpulse needs to be installed by a licensed electrician.

• The Rainforest Automation EAGLE-200 costs $100 and appears to be the best option. There’s even a Home Assistant plugin for the EAGLE-200. But it seems to be based around a cloud service, which is unfortunate. The same company also sells a stripped down EMU-2 device with a primitive dot matrix screen. It transmits usage data over USB via serial and the company released the Emu-Serial-API project on GitHub to parse the output with Python. However, the EMU-2 is not listed as a HAN product.

• The Universal Devices ISY series has an incoherent website, but seems to cost $126 for just the module portion of their ecosystem.

DIY

A MAC address is required to activate the Zigbee radio in the meter, and it probably only communicates with that specific device. It makes sense as a security feature, if MACs cannot be spoofed. The ecosystem around the Smart Energy Protocol in Zigbee seems locked down tight, with “production” certificates required to communicate.

• It’s unlikely a board based on the Nordic nRF52840, despite it supporting Zigbee, would be able to communicate with the smart meter, since it lacks certification.

• Texas Instruments has a guide on using one of their modules to monitor Smart Energy packets.

Discontinued

• Digi, known for their XBee modules, obsoleted their Smart Energy products, like the ConnectPort X2 SE, in 2016. Before that, they wrote a guide on setting up their generic XBee modules for Smart Energy.

• Until 2015, Rainforest Automation sold a USB stick called the RAVEn that was similar to the EMU-2, but lacked a screen.

• Google PowerMeter and Microsoft Hohm were two short-lived projects from 2009 to monitor home energy usage using smart meters. Hohm would use non-smart meter data sources at first and then transition to using them as more were brought online.

Pulse counting

Some meters emit pulses as energy is used. The Raspberry Pi-based emonPi monitor can sense these pulses to measure energy.

OCR

There are a few projects that use OCR to read the visual indicators of meters. The AI-on-the-edge-device (via Hackaday) looks the most promising. There’s also a water meter-focused approach at Integrating my Neptune Water Meter with HomeAssistant (via Hackaday).