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.
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, described further below.
The Universal Devices ISY series has an incoherent website, but seems to cost $126 for just the module portion of their ecosystem.
Rainforest Automation EMU-2
The EMU-2 transmits usage data over a USB serial port at a prescribed rate. The company has an abandoned Emu-Serial-API project on GitHub to parse the XML output with Python 2. Despite the shortcomings of that interface, emu2influx uses it to push metrics to InfluxDB. The most promising 3rd-party interface is Emu-Api (known as emu-power on PyPi), written in Python 3. The RAEdataset project also has a very simple EMU2_reader.py script, if full control isn’t necessary.
PG&E supports this device, despite not being listed as a HAN product.
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.
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.
Some meters emit pulses as energy is used. The Raspberry Pi-based emonPi monitor can sense these pulses to measure energy.
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).