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Hello and welcome. Taking those points that I can answer:

"I am planning to use a raspberry pi..." That's OK. You can use the PI either as the server running emonCMS (but ideally need to add a spinning hard disk for storage) or as a gateway to your LAN - Jerome has written the software to do that. I think several people has emonCMS running on various NAS systems. You'll need a static IP address of course.

[Two emonTx..] "That will cover all house electricity usage, right?" It would seem so. But when you say "group", is yours a single phase supply or polyphase? The emonTx is designed for single phase only, you ideally need one per phase if you have more than one phase.

"However, can I then use that setup to also monitor individual appliances" Unfortunately not. Trystan Lea did some work a while ago on "Appliance Inference" - the aim being to recognise the change when an individual appliance turned on or off so that you could identify which it was, and I've seen reports that others are also working on this problem. I'm not aware of a proven working system though. I think it's likely that the dashboards you've seen do indeed measure each one separately.

Thanks Robert,

All the groups in my house are 1 phase I believe (dutch electricity system). I found the github repo that Jerome has for offloading the emoncms from a raspberry pi to an external installation. 

Last question though: If I use two emontx's to monitor the 5 groups, will I be able to specify in emoncms (or elsewhere) that any additional emontx's (monitoring individual appliances on those groups) are monitoring parts of the inputs already received, to prevent emoncms from actually counting the group and the appliances within that group?

Maybe this makes it clearer:

EmonTx1 used to monitor groups 1, 2 and 3 at the meter.
EmonTx2 used to monitor groups 4 and 5 at the meter

EmonTx3 used to monitor fridge (on group 1), oven (on group2) and dishwasher (also on group 2)

The data EmonTx3 is monitoring, is part of the data EmonTx1 and 2 are already monitoring. What I don't want is that the values measures from all three EmonTx's are counted/added up, because that would give a wrong total energy usage.

Hope my question is clear... :-)

Thanks for reading!

AET

I wouldn't advise doing it that way, but you can certainly do it.  You can subtract one input from another inside emonCMS, with a little ingenuity. If you go to emoncms.org, under Using Emoncms -> Input processing, you'll find a list of operators. To subtract, you multiply by -1 and then + input. You can send the result part way though the calculation to a feed, continue and send the another intermediate result to a different feed, continue and send the final result to a feed.  (A feed is what gets stored for display, inputs are temporary and only exist between the time the data is received to when the calculations are done.)

(You really need to do this a few times to understand how the processing works.)

haha, thanks for your reply. I guess I am in for a little bit of experimentation after I get the hardware :-) I guess I will start with just the two emontx's to monitor the groups coming out of the meter...

If you register an account, you can experiment while you are waiting for the hardware. You can make up values and send them from a web browser! The Input API help tells you the data format and gives you simple examples.

Thanks, I read that somewhere already, so created an account and will get experimenting tomorrow! Awesome, can't wait! Thanks Robert!

Yay! Just placed an order for the hardware to monitor all 5 groups...

However, another question popped up: 

I played around with emoncms a bit, but did not find this (yet?): Is it possible to add a form on a dashboard to manually enter data into emoncms? I have (very) old utility meters in the house that do not emit any sort of pulses, so I am thinking about a way to enter the numbers on the meters manually on a regular basis. 

Is such a thing possible from within emoncms?

I think the answer to that is no. You could clearly do it by customising your local copy of emoncms, but I don't think it's likely to be available on emoncms.org any time soon - because the site is all about building the kit (that you've just ordered! ! !)  to send consumption data automatically!

(What you're really asking is how do I run a check automatically?)

I've never felt a need to do it, but I can't see a reason why you can't have a bit of software that does what the browser or the emonBase does and submits the data using the structure in the API help. It would appear as an Input and you'd log it to a Feed just the same as the rest of the data.

I guess I can whip up a page that offers a form to the user to enter meter readings and posts them to emoncms then :-) Shouldn't be too hard to do. 

Thanks again!