EmonCMS input processing in branches?

Hello All
First I want to thank all the developpers for this wonderfull platform.
There is a few weeks that emoncms is running locally to supervise my PV system.
I was very impressed that emonhub works immediately to log my SMA inverter through Bluetooth.
I have a question about the processing of the inputs.
We only have the possibility to have a sequential computing of inputs to feeds ?
In my case I have two East/West roofs and I want to compute feeds with power for each, so multiplying current and voltage and log the result.
Now to have the total power I add the other feed and log to a new feed.
If I want to have the daily Kwh for both roofs, how do I proceed ? Because in the processing sequence the last computation is the total power, so I do not have anymore access to the power of the single roof.
Hope you understand what I mean !! Perhaps better with a graphics:

Thanks for your support
Regards
Christophe

Hi Christophe,

Could you not use the Power to kWh/d process step after #3 to log directly to a new feed? This won’t affect the value passed on to the next step.

(The Power to kWh process step is potentially the better choice though, as it allows you to plot the delta for days, weeks or months, depending on what you want to see at the end of the day.)

I’m guessing you have a separate process list that logs to DCPwr1? Adding Power to kWh/d or Power to kWh to that list should give you want you want.

Input DCCurrent1

  • log DCCurrent1
  • x inp DCVoltage1
  • log DCPwr1
  • kwhd DCDaily1 ← add this step

Input DCCurrent2

  • log DCCurrent2
  • x inp DCVoltage2
  • log DCPwr2
  • kwhd DCDaily2 ← add this step
  • + feed DCPwr1
  • log DCTotalPwr
  • kwh DCTotalEnergy ← optional: cumulative total kWh

Hope that helps.

I would add to Tim’s answer: At the end of a sequence of process steps, you can always add Reset to original, which brings you back to the condition you had just before the very first process step.
You don’t need to (and should not) repeat step 1 Log to feed, you then repeat steps 2 (& if necessary 3) and then add your ‘kWh/d’ step etc.

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Thanks for your help Tim & Robert !

Just an other question. What is the difference processing with +input or +feed ?
I mean when the feed is directly the input, does it change something or is there a delay in the processing due to the sampling of the feed ?

There is a time difference, more particularly between the present input you are working on and others. The general advice is to use the Feed, and put the processing that uses it in the processing of the last input that you’re using in the list. For example, if you have the powers for three phases on inputs CT1, CT2 & CT3, in the processing for CT3 you would add +Feed: CT1-Power. and +Feed: CT2-Power. If in CT1 you did +Input:CT2 and +Input:CT3 there’s a danger that the CT2 & CT3 powers would be 10 s old when they were added to CT1 power.

Here is the explanation:
https://openenergymonitor.github.io/forum-archive/node/11033.html

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