Emoncms.org apps My Electricity shows negative kwh and cost of electricity

Can someone please tell me what I’m doing wrong.
Thanks in advance.

Welcome, terry, to the OEM forum.

Please take a look at the FAQ page. There are some hints there under “Asking for help”.

Our problem is, none of us are clairvoyants and we have no idea what you have and what you’re expecting to see.

What is measuring the electricity - i.e. where is the data coming from before it gets to emoncms.org? Is that showing sensible values?

I have looked through FAQ pages. I’m not looking for a clairvoyant. Just some simple help from somebody smarter than me. Thanks for your reply.

I would have suggested you have a wrong sign somewhere, but if you don’t want to supply any more information, I doubt anyone can help you.

Which feeds did you choose on the configuration page?

  • use - current watts being used by house
  • use_kwh - cumulative kWh consumed by house (always increases)

If you’re seeing negative kWh, then that suggests you’ve not fed it the right feed.

If you only have 1 input from your electric meter, then you probably need set it up to log to two feeds:

  • Log to feed → use
  • Power to kWh → use_kwh


Then again, if he has private generation and he’s using the wrong app, today’s export could give a positive power and negative cumulative energy and cost - we just don’t know, so everything is guesswork until we have more information.

Also note he’s in the USA, so I suspect he has their weird split supply, so if the two legs aren’t added correctly, all sorts of fun will ensue.

To start with I had brain surgery and a stroke a few years back and I’m not hitting an all eight cylinders like I was before. I have an IotaWatt that I put both of the CT’s on with the arrows coming in on both 110 legs.

When sending data from the IotaWatt to emoncms.org I get negative reading on My Electricity and My Electricity 2 Apps. I’m in Texas USA, CDT time and I set the IotaWatt and emoncms.org to -5 without Daylight Savings Time. When adjusting the time zone the negative number goes up and down with the change of the time zones.

I also noticed that the negative numbers go positive to negative at different times of the day and randomly.

The IotaWatt Status Screen has the Power_In_Right circle-arrow with the pf at .76. All other CT’s are normal with the pf at 1.00. I have reversed the direction of the CT manually and with the IotaWatt software and there is no difference.

Please see attached pics and if there is any more information needed let me know. As stated above please keep it simple, as I may have a hard time understanding what all you smart people saying.

Any help would be deeply appreciated.

I think there’s a mistake in the process list for your two inputs, as it looks like it’s trying to write both the log and kwh to a single feed. You need to be writing these to two separate feeds, then setup up My Electric app to use the log one for use and the kwh one for use_kwh.

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Thank you for you reply. I still can’t figure it out. Is there a video or instructions to follow on how this is done.

What @Timbones is saying is, you are mixing your units and adding your power and energy to the same feed. Let’s look at the Left first - it’s simpler:

It’s here:

Step 1 writes the power to the Feed iotawatt2: Power in Left 1
Step 2 takes the unchanged power from step 1, multiplies it by the feed rate (i.e. time) to get the energy (in kWh) over that time step, and then you write it to the same Feed iotawatt2: Power in Left 1

That’s where there’s a mistake, you should be writing energy and power to different feeds. It makes no sense to add watts and kWh together. Step 2 should write to a Feed called something like iotawatt2: Energy in Left 1 or iotawatt2: kWh in Left 1

Now looking at the Right, Steps 1 & 2 are fine. Step 1 gets the Power in Right and adds the Power in Left to it. Step 2 receives the result and writes it to the Feed iotawatt2: Power in Right 2. But Step 3 is where you mix things up and write the energy to the power feed.

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You need to Edit the last process (via the pencil icon) or delete it (with the trash can) and create a new one. In that new step, you can then CREATE NEW feed, giving it a unique name like “Energy in Left 1”.


Then you should have something like this, as @Robert.Wall described above:


This will give you the two feeds you need to supply to the My Electric app:


Repeat for “Power in Right 2”, and you should be sorted.

Hope that helps.

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WOW! It’s working like a charm. I can’t thank you both enough. Y’all should write an Emoncms for dummies book because this dummy wouldn’t have ever figured this out without you.

Thank you for all your help and I hope the best for you and yours.


Glad to hear you got it working :+1:

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