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Comment by bloopernova | Hacker News Reader

Wouldn't it be cool if every wall and ceiling socket could report its electrical usage? I wonder if that's possible via powerline networks, or if it would work over something like Zigbee?

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ZigBee could definitely do it but as someone with a lot of smart wall plugs (I have a total of ~40 ZigBee devices in my house) that data is just not really useful because it's just a drop in the bucket compared to cooling/heating/hot water.

One thing that would be more useful and that I really want to get is one of those amp meter for the distribution panel to see my power consumption in realtime: https://www.aliexpress.com/item/1005007038134809.html but I didn't get around to it yet.

This is what I've done; I use a Z-Wave power meter on my electricity meter for whole-home, then some individual ones for my desk/3dp/rack, the ~50 ZigBee devices I have are mostly bulbs or sensors (I also have another ~40-50 Z-Wave devices) and the majority are things that use very little power; the usage stats from those things is a rounding error.

For bulbs and sensors, the power usage isn't useful for automation either, you can use other data they provide (turn off lights when no one is around, do stuff when doors open/close).

For whole-home though, it can be useful to see if the power is higher than you'd expect; if it's not dinner time and we're using 2kW+ for more than a few minutes, send a notification in case someone left an electric heater or an iron or something on.

I'd appreciate smart plugs with bidirectional communication, as real-time power use report + ability to switch the plug = poor man's way to turn most devices into IoT devices for local control. It would help in particular with ones operated by IR remotes, which deliver commands but don't get feedback on their state; you could observe device's power consumption to infer the current mode of operation, providing a bidirectional control abstraction in e.g. Home Assistant.

Not sure if I am understanding correctly but getting power consumption and being able to turn the switch on and off is definitely available in even cheap ZigBee switches: https://www.amazon.ca/THIRDREALITY-Real-time-Monitoring-Comp... (~12$ each).

I have two of these(1) Emporia Vue2 units in my home, one in each load center. I have them flashed with espHome and integrated into HomeAssistant.

I really love that they give whole home power usage, as well as up to 16 individual circuit usage details. And with espHome into HA, all local control with no cloud dependency.

(1) https://shop.emporiaenergy.com/collections/in-panel-energy-m...

I used to work closely to this on whole home energy disaggregation. There are products for doing this, but the value is very limited.

Excluding EVs, heating and cooling is the largest factor for energy consumption followed by other large appliances. Small appliances and electronics don’t use much electricity or aren’t on long enough to matter.

If you’re interested in some product recommendations, the Sense Energy Monitor used to be a popular choice. Basically it is a set of clamps that you can attach at your breakers to monitor specific circuits. It’s good for monitoring large appliances with their own dedicated circuit. For individual appliances, a Kilowatt Meter works fine. If you want something for continuous monitoring long term, I’d look at the Eve Smart Outlet.

I have a Sense Energy Monitor. It works pretty well, but I wish they made their own smart outlets to integrate with the panel monitoring.

Anyways, some pretty clear trends emerge when tracking your energy usage. Climate control (heating, cooling, fans, dehumidifier) dominates my energy usage, then EV charging, the kitchen stuff (refrigerator, cooking, dishwasher), then electronics (and I have a ridiculous amount of them), clothes dryer and lighting. I would like more insights into my electronics for personal curiosity (which Sense can't seem to do), but in the scheme of things it probably doesn't matter. No individual electronic device is going to make much of a difference.

Not quite every socket, but iotawatt can monitor each circuit at the breaker panel, and from there, it's generally not too hard to figure out what's going on, and it's really nice to be able to get a concrete sense of where your electricity is going (for most people with a heat pump, it's mostly the heat pump, it swamps even our EV). It's local-only, no cloudiness, and it's been rock-solid for us.

This sounds pretty cool. I just went through the docs but I can’t tell physically how you install the CTs. Our mains come into the house underground and into the electrical panel and of course the wiring is all in the walls. Are you supposed to open up the walls and attach the CTs to the wiring in the walls? How would this even work for Romex that runs along framing?

The CTs go inside your panelboard around each hot conductor. The CT leads go back to a separate meter enclosure.

Here’s a commercial grade submeter cutsheet with a diagram to illustrate: https://leviton.com/content/dam/leviton/lighting-controls/co...

You just turn off your main breaker, open up the panel, and snap the CTs/current transformers around one of the wires on each circuit (you can open them back up if you mess up). You only want to put one wire through, rather than a full romex bundle, because it measures the flux through the loop, and the return path would cancel out the reading.

It does take a bit of reading to figure out eg what to do with 240v circuits (you can usually double it if you don’t care about absolute precision, usually one leg has the control electronics on it and is a bit higher). Also, it doesn’t have quite as many channels as most panels’ max # of circuits, so you might have to choose, or try to run multiple wires through one CT.

If you’re uncomfortable with going into the panel (reasonable), you can probably find an electrician that’s willing to put it in/make it pretty.

I think I saw some YouTube videos of people installing them diy before I tried, that might help get you more comfortable with the process.

You can definitely do this with ZigBee, I have smart light-switches that report usage; though I'd argue the lights are the least useful thing to have usage reporting for, since I already know the power consumption of the bulbs, and since I'm using LED everywhere, it's negligible compared to the rest of my usage.

The problem with ZigBee is network scale and interference, but also you're wasting energy by having electronics in every socket, always on, always reporting. You're also then driving your server harder and storing more data, costing more.

I've aimed to strike a balance of only making smart the things I actually care about power usage for; my server rack, my 3D printers, my desk, and then whole-home as a single unit.

I don't need to know how much my washing machine or oven uses, if I need to use them, I need to use them; there's little room for optimising.

When it comes to optimising which settings I use, if I care enough, I can use a temporary ZigBee power meter that plugs in like a normal device; record data for days/weeks/months and adjust based on the result of that.

Exhaustive data has nerd appeal, but in practice, you'd add power, circuitry, and RF noise overhead to mostly see signals that maintain very stable patterns for as long as the same thing is plugged into it and used in mostly the same way (i.e. for months or years).

All you really need is snapshot understanding of what a device really consumes, and only then if it's non-negligible and some alternative might make sense.

For outlets and receptacles, you can achieve that by just inserting a meter where you want. Per-circuit metering in the distribution/circuit breaker panel would be nice though.

You can get KNX switch actuators with per-channel True RMS / active power metering. They're like 40 bucks per channel.

There is a company that does this but senses direct from your circuit breaker panel. The uses FFT plus algos to determine individual devices on each circuit from their unique electrical signature. Called Sense I believe. I’ve never used it.

On a geek level it would be cool. On a practical level? My electric bill is $100 in January and $400 in July. I know what's going on.

if only! i know this is not what you’re asking for, but inexpensive Sonoff outlets flashed with firmware and reporting to Home Assistant are how i monitor (and switch on and off!) the largest consumers of electricity in my home. it’s a good two-weekend project

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