Emoncms - differences in kWD for self hosted compared to emoncms.org


#1

Hi All

I moved my IotaWatt to emoncms.org reporting, when I did this I found the kW/Day reporting to be pretty much the same as the reports direct from the Iotawatt graphs +/- 0.2kwh for the day - all good.

Recently I have decided to move a range of other sensors to emoncms and given costs decided to self-host emoncms. I am running this on Ubuntu/MYSQL/PHP7.2. The IotaWatt feeds are configured identically to the emoncms.org version. I loaded the hsitoric data from my Iotawatt and now find that all kWd values are around 13% higher than what was being reported by emoncms.org and directly on the iotawatt.

Has anyone seen anything similar or can provide any insights

Thanks, Dean


#2

Without a specific case, you are inviting wild speculation. I’m sure this has an explanation. The starting point would be to look at the EmonCMS configuration on the IoTaWatt and the inputs on Emoncms, you should be sending watts to EmonCMS, and then logging those watts to a feed then to a kWh feed.


#3

@Deancs had thought initially that I had a similar problem but it turned out to be configuration/timing. Hopefully this info helps get you going.

Please note EmonCMS daily totals only line up if your emoncms host and emoncms instance are configured correctly (to be in the same timezone as the iotawatt).

This means the reporting will line up for daily totals etc. In my case, thats +10 (Sydney) and I get new totals at 10:00am each morning. Its 10:00am as it totals at GMT/Zulu 0:100: Also keep in mind that emoncms daily lags by 1 reporting period vs IotaWatt Graphs as they show current.

That further compounded as the “current usage” is calculated from midnight local emoncms time. So be aware of what values you are looking at / comparing.

Here is a link to my emoncms page (screenshot below). The top stuff is realtime/current (calculated from 00:00).
You want to look at mains total vs solar which is the 4th graph. If you hover over the totals you will see that align to my iotawatt values.

(This is the graph you are looking for)

Here is a screenshot from iotawatt…
I left the CSV in there so you could see the totals.
(Daily totals line up to about 4 decimal places and I stopped looking after that and rounded everything back to 2 places.)

How did I get this.

  • Hosted config of emoncms (its on a Ubunutu instance in azure of all places…long story). Date/timezones configured to be same as local.

  • Iotawatt - the graph you see (Energy/Weekly view/Daily Delta)

  • IotaWatt - webserver being send the mains total in watts. I can send you my screenshot but its a bit more complex as its three phase and doing some totalling first.

  • emonCMS - logging as follows:

  • emonCMS - graph as follows:

Double check everything and give it a day or so…


#4

@bluetardis, may thanks for such a comprehensive reply. I think you may have nailed it, my ubuntu TZ was UTC and not +10 (North East Vic). I have updated and will see what tomorrow brings.

I like how your dashboard shows total daily kWh and then % of that total for each of the circuits - very neat.

I’ll check back once tomorrows results are in !


#5

Unfortunately its not super easy to share the dashboard but… to get those working…

This to me was more useful for education of other home occupants - eg knowing that 50% of our usage is hot water is better than its 14kwh - you can still see the totals.
Also you can see as much detail as needed daily or trend by playing around with the other graphs.


#6

Nice…understood and will be creating some of those.

Also happy to report that daily kWh reporting of self hosted matches emonms now that TZ are aligned. I just have to reimport historic data from IotaWatt

Thanks again for your help