Getting the real time DATA


I have a Secure Liberty 100 electricity smart meter.
I need a DATA terminal to give me the consumption in real time, so I can control various electric consumers.

Basically, I have a 4kWh solar panels, and when the smart meter tells me I have sufficient electricity generated by my solar panels, I want to turn ON some consumers, and when the solar generation drops, I want to turn them OFF.

To turn the consumers ON and OFF is my problem, that I can solve if I know when (meaning I need to know the consumption in a real time basis).

Can anybody give me a suggestion?



There are various diverters on the market (the Eddi is one I think) that will divert excess Solar rather than export it. These are ‘real time’ as they adjust the output multiple times a second and are most useful for charging batteries. I’m thinking you do not actually want ‘real time’ as turning devices on/off regularly is usually not a good idea :slight_smile:

The only way to get close to ‘real time’ load is using CTs and something like an emonTX. However, this is still not ‘real time’ as it only reports every 5s.

Depending on your supplier, there are different ways to get ‘close to real time’ load information (Octopus Mini for instance). You can also get a Glow IHD (Our Products – Hildebrand) which will give you a 10s MQTT feed.

For decisions on turning on/off, I’d say use HomeAssistant.


Hi borpin
and thanks for your reply.

emonTX with a 5s report seems OK for my needs

Are there any experts on this emonTX to explain to me how it actually works?
For example, I’ll get one with 2 CT sensors only
One to monitor the mains 240VAC income
And one to monitor my solar generation.

How does it differentiate between the two?
Or better said, when my solar would generate and export the surplus, wouldn’t the mains 240VAC income CT sensor think that my generated (and exported) energy is in fact all imported energy?

Can this emonTX detect the direction of the energy?
How, if it’s AC?

And second explanation I’d like is: how is the emonTX reporting what is monitoring?
etc . . ?

Thank you.

Have you read through the docs? I suggest you start there looking at either an emonPi (all in one solution V2 available shortly I think) or the EmonTX with the emoncms software hosted separately.

thanks again borpin

have you got a quick link to these docs?
I can’t seem to find them.


I’d go standalone; totally ignoring your Secure Liberty 100, as its data is likely to be slowed down for the off-site utility company, and try for a solution which uses a CT probe on your meter tails (with the emon low Voltage AC-AC transformer based Voltage probe to find the time of rising zero crossing in every 20ms mains cycle) and decide your switching locally and promptly from household net power. That way, while the kettle or oven thermostat draw much of your solar power, your interruptibles on your new 3 pin socket for <13 Amp interruptible loads will stop until power is available according to your new project gadget. Did you know that a competant bodger can epoxy a mains rated relay inside the housing meant for a 3-pin socket or two? That way, the small hole drilled into the side of it only carries low Voltage 5V 100mA wires to activate the relay or other device; all mains connections including nasty hand soldered mains wires on relay pins stay inside a mains rated housing and well away from clumsy fingers.

There’s a link at the top of every page in the forum. For basic principles, look for ‘Learn’, then ‘Electricity Monitoring’. For technical details of OEM kit, look under the name, e.g. ‘emonTx4’.

Yes, by comparing the phase of the two waves, voltage & current - guess where to find the details: the Docs :wink:

You put one c.t. on the P.V. infeed, and one on the main incomer. They have separate inputs and report the values of power & energy separately. House consumption is the (algebraic) sum of the two. Our convention is power into the house is positive, so +3 kW of P.V. and - 3 kW on the grid means zero used in the house.

An obvious no to this, because it knows the direction of power flow. (Unlike quite a few systems you can buy.)

Either ISM Band UHF radio to the emonBase or an add-on Wi-Fi module to either the emonBase or even our ‘cloud’ emonCMS service via your router (chargeable, but with a substantial discount when buying our own products), or serial USB. Note that only accepts data every 10 s. 5 s reporting is not the default, but it be changed very easily.