Smart Energy Monitor

[daedalusminos]

OH has a small pottery business with 9kW kiln for which she has a need to keep tabs on electricity usage for business purposes. Up until recently that was fairly straight forward since it was on a single rate meter and the kiln reported usage in kWh and therefore cost of each firing could be determined. With the recent shake up in electricity providers the kiln is now on economy 7 (which TBH is probably a good thing) however that now makes calculating the cost more difficult since the 12hr firing spans both rates.

The property is Smartthings equipped and the ideal solution would be for a smart energy monitor to report the accumulated electricity cost in the Smartthings app with the accumulated cost being re settable. I would need accuracy of approx 1%

Ideally something off the shelf since I don't have too much time to tinker but nothing appears to tick all the boxes - the Shelly 3EM comes close, and although designed to run in a propriety environment, looks as though it can be linked to Smartthings However, it looks as if any dual rate calculations would have to be done in software.

Shelly 3EM

shelly.cloud

Anyone got any better ideas - I know @Dev @JMS1972 and @bigegg have been working on energy monitors.

 

[James1979]

Dunno if it helps but my workshop is in the yard at home.

Electrician put a second meter in for me so I can offset the right amount against income and more importantly prove it.

I bought what I was told but it’s a solar panel meter (?) I think he said from eBay. He just put it in the feed to workshop.

 

[gaz1]

also use a second meter is the best option as anything business related is on that meter with its own junction box

we used them with flats and fitting out units with electric power

its easier to calculate whats business use and what is home use

 

[bigegg]

OH has a small pottery business with 9kW kiln for which she has a need to keep tabs on electricity usage for business purposes. Up until recently that was fairly straight forward since it was on a single rate meter and the kiln reported usage in kWh and therefore cost of each firing could be determined. With the recent shake up in electricity providers the kiln is now on economy 7 (which TBH is probably a good thing) however that now makes calculating the cost more difficult since the 12hr firing spans both rates.

The property is Smartthings equipped and the ideal solution would be for a smart energy monitor to report the accumulated electricity cost in the Smartthings app with the accumulated cost being re settable. I would need accuracy of approx 1%

Ideally something off the shelf since I don't have too much time to tinker but nothing appears to tick all the boxes - the Shelly 3EM comes close, and although designed to run in a propriety environment, looks as though it can be linked to Smartthings However, it looks as if any dual rate calculations would have to be done in software.

Shelly 3EM

shelly.cloud

Anyone got any better ideas - I know @Dev @JMS1972 and @bigegg have been working on energy monitors.

My method:
(This will seem *much* more complicated than it is. Each step will only take a couple of seconds to a minute, at most)

Install home assistant on a rasp pi, or old PC. (I use a Dell z90 thin client for sub £20)
Buy a CT sensor.(£5?)
Buy a mottramlabs single sensor interface. (£10?)
Buy a weimos D1 mini (£5?)
Buy a 1A usb power supply.


Install ESPhome on HomeAssistant, then "add device" and install firmware to D1 via USB cable.
Plug mottramlabs interface onto D1,
plug in CT scanner,
fasten CT clamp to live cable on kiln.
Power up D1

Edit "EspHome" device firmware to add the CT sensor details and upload to D1.

This will now give you a working kWh reading in home assistant.

Create a "helper" variable (entity): "unit price"
Go to "energy" dashboard in HomeAssistant, the auto setup will give you an option for "price from entity" - use the "unit price" entity.

Now the clever bit.

Install the "scheduler" integration into HomeAssistant.

Set up a schedule that changes the "unit price" at the correct time.

You now have real time updated usage - including hourly, daily, weekly, and monthly costs.

Most of the "work" is done automagically.

The only soldering is to the D1 if you get one without pins already installed.
The D1 and the interface fit easily into a single backbox (unlike, say, an Arduino).

Apart from the actual home assistant install, that takes around an hour, the rest of the job could be done in less than 10minutes. 30minutes as a beginner - maybe an hour if your Google-foo isn't strong.

(Hint: google "EspHome CT sensor" brings up a wiki page with just about everything you need to know).

 

[Kayos]

I have just sold a small(ish) meter on here

I will see if I have another one hiding in the shed

 

[Dev]

The monitoring is the easy bit - sounds like even a single channel shelly em would do.
Recording and doing the maths for the 2 rates is trickier. I don’t know enough about smart things to know if you can do custom reporting like that.
Home assistant and grafana could do it but it’s as far from off the shelf as you can get.

 

[bigegg]

The monitoring is the easy bit - sounds like even a single channel shelly em would do.
Recording and doing the maths for the 2 rates is trickier. I don’t know enough about smart things to know if you can do custom reporting like that.
Home assistant and grafana could do it but it’s as far from off the shelf as you can get.

grafana is not needed: homeassistant has a built-in energy monitoring system

 

[JMS1972]

Have you looked at the Emporia energy monitor? That has 50A max current clamps.

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Not too expensive for an off the shelf system. It's all proprietary though so maybe not what you want...

 

[carbon]

Have you looked at the Emporia energy monitor? That has 50A max current clamps.

I’m using that with home assistant. Easy to monitor different circuits

 

[Dev]

grafana is not needed: homeassistant has a built-in energy monitoring system

How do you do the filtering so consumption between 0900-1800 is one price and 1800-0900 is another price using the inbuilt monitor? performing the filtering and maths if the bit i’d use grafana for

 

[JMS1972]

I’m using that with home assistant. Easy to monitor different circuits

Can Home assistant access it directly or is it via their server? Also can it detect negative current flows? E.g solar...

 

[bigegg]

How do you do the filtering so consumption between 0900-1800 is one price and 1800-0900 is another price using the inbuilt monitor? performing the filtering and maths if the bit i’d use grafana for

Create a helper variable to hold the unit price, then change the value using the "scheduler" integration.
Much less overhead compared to grafana - which I found pushed a rasp3b to its limits.

 

[carbon]

Can Home assistant access it directly or is it via their server? Also can it detect negative current flows? E.g solar...

At the moment I'm using a hacs add on that accesses the emporia server for data, but it is possible to flash esphome to one and access it locally. I believe solar is possible but havent checked the manual

 

[8ob]

Sounds like a job for two meters set at the different tariffs and two timers , everything else sounds like vodoo to me

Bob

 

[daedalusminos]

Thanks for all the replies.

If I had more time to invest then I'd probably go down the MottramLabs interface and Weimos D1 mini, but I'm also not that keen to start a learning curve into HA and would rather stick with just the SmartThings.

I did look at the Emporia energy monitor but was quickly put off by the fact that it appears to be only proprietary cloud based and there were suggestions that they could start charging for access on a subscription basis - probably just rumours but it wouldn't be the first time.

With that in mind I've turned my attention to the Shelly (3)EM, it looks as though the EM can monitor two currents and one voltage and at £65 inc two CT's is quite affordable. The 3EM can monitor 3 currents and 3 voltages so true 3 phase but at twice the price. Both have built in real-time clocks and log to internal memory on 5 minute interval which could be handy. Moreover they can be connected to Shelly cloud or run in standalone mode - they even provide a programming header should one wish to flash 3rd party firmware.

I know I can link a Shelly cloud account to SmartThings so should be able to access the readings - will just need some Smart app/Webcore to manipulate to give cost.