Newbie looking for advice


I have a 3 KW PV system that has been in for just short of 12 months, its made a huge difference to they way do things and greatly reduced our pull from the Grid, but there is room to squeeze more from the system and i think that has to start with decent monitoring, something we are currently lacking.

I have been looking at the PV monitor kit bundle

reasonably confident of putting the kit together if i take my time with it,

I have a Raspberry PI that can be used as base station,

I want the emonGLCD sat in the living room, but i also want a web based access to live / historical data - this is where Emoncms steps in,

To use Emoncms do i need to belong to with my data uploading or can i host / run everyting i need from home?


Where is the best place to start ? ordering the kit and putting it together, get the emonGLCD running, or download and set up Emoncms / any other software i need and get the hang of it ?


Once i have monitoring in place i then want to move onto diverting our excess towards our immersion rather than back into the Grid, so im then looking at the Mk2,

Bit more cautious with this as it involves connecting into the mains, would be looking for the help of an electrician whan that time comes,

Would i need to change our immersion from the current 3kw one fitted to a lower power one as needed with some systems or will it run the 3kw immersion with what ever excess is available?


I have also been looking for some sort of device that will allow me to turn mains sockets on / off via the web, i found the Belkin WeMo Insight switch but have been told by Belkin that this is not coming to the UK, watch this space for something else, how ever rather than watching for something i have no idea when it will be arriving i will ask if any one nows of or is using anything that will do this job for me ?


Thanks for any pointers / suggestions any one can give me


Robert Wall's picture

Re: Newbie looking for advice

Hello Keith, welcome.

Dealing with the easy one first - I don't know about remote control sockets, but no doubt somebody here does.

As for the sequence to do things, I'd order the kit and build it. The emonTx and GLCD will work together without a base. If you use a GLCD sketch that shows the date and time, the display won't have that because it come from the server and will complain, but that's all.

If you go for MartinR's PLL design (posted a while ago but the write-up published only last night), you can have immersion control and monitoring in one emonTx.  As you rightly say you need to break into the immersion feed by your consumer unit, but alternatively you could link the triac switch to the emonTx with a telephone pair or one pair in a CAT 3 cable (or similar).

Robin's Mk2 variants I think include one that does load control by radio, so that might appeal, but none of Robin's do monitoring as well.

You don't need to change the immersion heater unless you have problems with flicker. The heater is controlled continuously to balance exactly the spare power available.


Keith Drayton's picture

Re: Newbie looking for advice

Hello Robert, Thank you for the welcome.


Im sure kit purchase is not far away, just need to confirm the funds,


I have been doing a lot of reading since my original post, 

Could you point me in the direction of the 'write-up published only last night' ? not sure if i have read that or not.

using MartinR's PLL design sounds good,


Can i buy any of this extra required hardware for the immersion control as a kit or pre built ?


Looking at what the PV system has export since installation i think there is a good benifit to diverting this to the imerssion.


I need to purchase my self a decent soldering station before starting any soldering projects, luckily the wife wants a soldering station for her jewelry making so no issues with spending on that.

As soon as i have the kit built and working i want to get web based monitoring running.


Then to look again and web controlled sockets / devices

pb66's picture

Re: Newbie looking for advice

Hi Keith,

Could you point me in the direction of the 'write-up published only last night' ? 

You can find Roberts write up at  this new documentation gives a great insight into Martins PLL design (Thanks Robert),


Can i buy any of this extra required hardware for the immersion control as a kit or pre built ?

Section 9 of that documentation explains the hardware similarities to Robins Mk2 design and has a link to source a kit from. Robin also had some custom heatsinks available here


Looking at what the PV system has export since installation i think there is a good benifit to diverting this to the imerssion

Definitely, By monitoring you can manage usage and make the most of what's available and by diverting the surplus very little if anything slips through the net During the summer it's easy to make use of the PV when you are fairly sure of the weather and PV output, but at this time of year it gets harder as PV output is much lower and spurious, using a diverter makes sure nothing escapes. ;-)


Keith Drayton's picture

Re: Newbie looking for advice

Thanks pb66 that was the was one of the articals i had read so looking at the right things, that's a good start :)


So i buy this kit

build it and fit it,

i then look at this article section 9 Hardware

and need to add the Triac switch to what i have above, so do i want all of ths

if i am looking at the PLL design or just a part of it, and then how / where do i connect that back to the emonTX


Or have  i completey misunderstood, i can follow instructions, build, install, not so great on the design side of things 

pb66's picture

Re: Newbie looking for advice

The picture is of a complete Mk2 diverter and arduino uno ie Robins design, if you are going to build an EmonTX kit for Martins design you only need to add the output board which is the small board on the right, attached to the heatsink. This output or triac board is quite simple to make from stripboard (as per notes in section 9) or I believe you can purchase the output PCB as a kit here, (the post is dated Feb 13 so you will have to PM richmc to confirm price and availability). Either way you will also need a heatsink and a 3.5mm jack plug to connect your output/triac board to the pulse socket of the EmonTX.

Also note you need the usb programmer to install software to the EmonTX and the kit doesn't include a 5v DC power supply to power EmonTX.


Keith Drayton's picture

Re: Newbie looking for advice

Thanks Paul very helpful, I will PM richmc and go from there.

Robert Wall's picture

Re: Newbie looking for advice

A note of caution: some while ago we heard that Rich was poorly and going into hospital. We've heard no more so a PM would be well advised. He did publish the pcb layout so it could be made elsewhere, otherwise stripboard (if done carefully) should be fine.

If you are sharing, consider a temperature-controlled soldering station and make sure you can change the bits easily.

Here's what I think you need in the way of hardware (no web monitoring):

1 x emonTx bundle
1 x FTDI programmer
2 x Mini-USB power cables                           )
2 x USB 5 V power supply plug-in adapters )  one for the emonTx, one for the GLCD
1 x 3.5 mm stereo jack plug
1 x stripboard or Rich's PCB
1 x opto-trigger i.c.
1 x triac and mounting kit
1 x heatsink
resistors, capacitor (X-rated) on the trigger board
terminal blocks 15 A
1 x box

As I mentioned, if you are able to run a light duty ('telephone') cable, you can separate the emonTx and the triac switch and fit the latter close to the immersion heater (in a cool but accessible place - not covered in lagging and insulation!).

Here is an emonTx (without the RFM12B) with 3 outputs and a 4 channel triac unit (3 working, one spare) with the thick-walled die cast box being used as the heat sink. The two units are some tens of metres apart and are linked by a 3-pair telephone cable. (3 immersion heaters & 3 tanks is a long story, and the green LEDs in the terminals are just for testing!)

Keith Drayton's picture

Re: Newbie looking for advice

Thanks Robert, that is just about the same shopping list i had put together,

I have read messages saying Rich was poorly, Hope he is doing OK, i have not PM him yet.

i may or may not look at splitting the location of the emonTX and triac, the tank / immersion are on the 2nd floor in the airing cupboard, not to cool in there, but they are directly above the understairs cupboard that contains the consumer unit and PV meter etc.


I want a emonGLCD, but i also definitely want web monitoring, i think i have read a base station fitted with a RFM12B can receive from multiple emonTX but can a single emonTX transmit data / run the required program to run a emonGLCD and to a PI base station?

Keith Drayton's picture

Re: Newbie looking for advice

Think i have just answered my own question by reading this (sure i have read it beofre but oh well)


so i have the emonTX output to the base station PI then feed teh emonGLCD from the PI

Robert Wall's picture

Re: Newbie looking for advice

Nope. It's not clear from the diagrams, but what happens is:

The emonTx broadcasts energy readings. The same message is picked up by both the emonGLCD and the base. The base forwards the data to the server that runs emonCMS.

Every minute, the base asks for the time from the server. It then broadcasts this, which the GLCD receives and uses to keep its internal clock synchronised.

The GLCD can also broadcast the inside temperature, which the base receives and forwards to the server and emonCMS.


The emonTx could, but isn't programmed to, listen to and act upon any broadcasts.
The GLCD complains gently if it doesn't get the time (in the demo sketch).
The base sends RF Fail messages to the server if it doesn't hear from the emonTx regularly.

Keith Drayton's picture

Re: Newbie looking for advice

And i can run a emonCMS installation on a ubuntu VM on my server, the PI will talk to that over my network, rather than using, just want to keep it all on site.


Thanks for all the replies, along with reading and re-reading articles / pages / forum threads im really starting to understand what im looking to do and how to do it.


Now to come to an agreement with the better half on which soldering station to buy, then onto purchasing the kit.

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