Monitoring electricity usage at the meter
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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:
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The AzTech in-Home Display costs $150 and seems stuck in 2002.
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The Embertech Emberpulse needs to be installed by a licensed electrician.
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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.
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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.
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.
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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.
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Texas Instruments has a guide on using one of their modules to monitor Smart Energy packets.
Discontinued
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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.
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Until 2015, Rainforest Automation sold a USB stick called the RAVEn that was similar to the EMU-2, but lacked a screen.
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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).