I use an EmonTX and EmonCMS to monitor my energy.

Its extremely configurable, with a vast feature set, but doesnt generally have the "polish" of some of the commercial products.

 

Also, many of these devices, including Loop, seem to only measure current. The voltage is assumed (and will be wrong) and they cant measure power factor, so they're not actually measuring real power.

EmonTX properly measures voltage and current, and properly calculates power factor.

 

EmonTX properly measures voltage and current, and properly calculates power factor.

I've been looking at this just recently. I was aware that EmonTX did proper voltage and current measurement, but I can't see anywhere on the website how it gets the voltage measurement. They sell the CT clamps but I can't see any voltage sensors. It looks like it's powered by either a brick PSU or a battery, so it can't be getting the voltage from that, there must be some other sensor?

The website says:

• 4 x single-phase current sense (CT) channels
• 1 x AC VRMS Channel

But they don't appear to sell a voltage sensor.

Also, is there any way of monitoring gas usage? It's a shame the gas meter doesn't have a pulse output.

 

Thank you @Aragorn, that's a really interesting option. Don't have time to sit and read it properly just now, but I like that there's loads of tutorials about how it works on the website.

From a very cursory glance it looks like I could keep it simple by just using a CT clamp on the main electricity meter. But I could also potentially stick one around the cable to the car chargepoint? I think I could stick a pulse counter on the gas meter. And in future it could be used with solar and batteries?

Lots of customisation, lots of data and lots of stuff to learn about along the way. What's not to like?

 

I have an Home - Brand - sold by the same OpenEnergy folks who produce the emon mentioned above.

Sensor Nodes - IotaWatt - Shop | OpenEnergyMonitor

 

This is why I love this place. Plenty of people with similar interests to me, but with lots more experience and knowledge they're willing to share. Thank you both.

 

I had an Owl Intuition for a couple of years. The analysis functionality of the website was pretty basic and the data download function didn't work properly so I couldn't do my own data analysis either. They started charging a subscription so I haven't looked at them since.

The main problem I had was inaccuracy at low power values; getting a smart meter really made this obvious that the CT clip seemed to read too high at low values, such as reading 110W when the actual value was 50W. This ended up overestimating overall consumption by almost a third. This rendered it pretty pointless.

Whether this was a faulty sensor, a poor design or just an inherent problem with using CT clips on domestic supplies I don't know. We don't have a smart meter now, so I have been looking at monitors that sense the flash of the LED on the meter instead.

 

The main problem I had was inaccuracy at low power values; getting a smart meter really made this obvious that the CT clip seemed to read too high at low values, such as reading 110W when the actual value was 50W. This ended up overestimating overall consumption by almost a third. This rendered it pretty pointless.

I suspect that it wasn't low values per se, but a problem with devices that draw power with high harmonic content and hence low power factor. These tend to be low power devices (PCs, TVs, LED lamps etc) because regulations force higher-power devices to be designed for low harmonics.

So in your case you maybe had 50W worth of those ill-mannered electronic loads that were misrepresented as 110W; if you turned on a 2kW heater you'd maybe read 2110W - which isn't that the accuracy has really improved from 100% error to 5% error, rather that you've still got the same chunk with 100% error and a new chunk with 0% error.

 

As @Peter Galbavy says I think it's pretty impossible for now.

Apparently although it's SMETS1 it's one of the meters that can be remotely enrolled into the DCC and Bulb plan on doing it next year at which point it will be officially SMETS2. They are also working on an API, which would save having to try to acquire the information locally.

That's fine for the gas meter since it only sends at 30 minutes cadence anyway, but still doesn't let you log the 10 second cadence data from the electric meter. It's a shame to have to buy extra monitoring stuff when everything is there already and transmitting, if only the signal could be logged.

 

Not just voltage but it also samples the waveform to get the correct phase N times a second, but only when the wall wart is used. Accuracy for voltage is within about +/-2% but can be calibrated (which I never did).

 

Does anyone have any experience with getting your energy supplier to pair a CAD with your smart meter?

This claims to be compatible with my Elster smart meters, and provides a nice SDK to pull the data over ethernet. But it has to be paired by the supplier to be allowed on the HAN.

Glow Zigbee CAD for Smart meters

 

Does anyone have any experience with getting your energy supplier to pair a CAD with your smart meter?

This claims to be compatible with my Elster smart meters, and provides a nice SDK to pull the data over ethernet. But it has to be paired by the supplier to be allowed on the HAN.

Glow Zigbee CAD for Smart meters

That does look interesting! I'm after something similar.

My smart meter is in dumb mode because I switched supplier. If I managed to get it paired I'm wondering if it would work still.

 

Quick updated after further communication with Hildebrand:

It turns out the Glow CAD cannot work offline. The API that Hildebrand make available is purely for getting the data back out after they have stored it. This means that it can't work without an internet connection, and most importantly it will become a brick if/when they cease to support the services. That's a deal breaker. I just want an Ethernet-Zigbee bridge device that lets me access the realtime data.

What are the chances of Hildebrand dropping the services? Well they currently run energyhive. They are no longer promoting or selling energyhive-compatible hardware, or making improvements to the existing services. They are shifting from energyhive to their new ecosystem called Glow. How long will it be before they decide Glow needs to be deprecated for another new ecosystem?

Not only that, but the web dashboard that is mentioned on the CAD page of the Glow shop, linked above, is still under development. Odd they don't mention that in the sales blurb before you purchase isn't it? The new app is called "Bright" and can apparently be found on the Play store, but they couldn't be bothered to give me a direct link. I wonder if any of them have ever tried searching for "Glow" or "Bright" on the Play store? Go on. Give it a try. I'll wait. Did you find it? Because it beats me.

How disappointing.