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Calculating electricity bill versus solar.

  • 20-05-2024 1:01pm
    #1
    red bellied
    Registered Users, Registered Users 2 Posts: 358 ✭✭


    I can see my bill is at least technically wrong. Looks like the readings for March works out what I got in April. Obviously I got more solar generation for April but the bigger bill is for that month and March is smaller issued by Flogas. How can I accurately check overall? How reliable are the stats generated by the clamp that runs from inverter to fuse board? I roughly checked and it looks like about 15kwh in difference.



Comments

  • #2
    ELM327
    Registered Users, Registered Users 2 Posts: 22,639 ✭✭✭✭ELM327


    https://www.boards.ie/discussion/2058352440/calculating-electricity-bill-versus-solar

    15kWh over a month? That's c500wh per day and probably well within margin of error



  • #3
    red bellied
    Registered Users, Registered Users 2 Posts: 358 ✭✭red bellied


    Would be 15kwh roughly over the two months. Need to check it properly later but originally it was seeing March was the smaller bill against April which rang the alarm bells.



  • #4
    DC999
    Registered Users, Registered Users 2 Posts: 1,542 ✭✭✭DC999


    https://www.boards.ie/discussion/comment/122160988#Comment_122160988

    15kWh over a 60 day billing period is only 0.25kWh a day variance. Every meter I had reads somewhat differently. But only the ESB meter matters. Plus every electrical system has losses.



  • #5
    red bellied
    Registered Users, Registered Users 2 Posts: 358 ✭✭red bellied


    Ya that's all interesting going forward just I can see that I have still been billed wrong so just wary.



  • #6
    graememk
    Moderators, Home & Garden Moderators Posts: 6,634 Mod ✭✭✭✭graememk


    CT possibly would have a variance of a few %

    Also the logging on a lot of inverters are 5 minute intervals which can miss spikey export, and also can miss spikey imports too.



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  • #7
    red bellied
    Registered Users, Registered Users 2 Posts: 358 ✭✭red bellied


    I use home assistant updates maybe every 60 to 90 seconds but it's the exact same data as the solarman app when I compare both. But I get your point.



  • #8
    graememk
    Moderators, Home & Garden Moderators Posts: 6,634 Mod ✭✭✭✭graememk


    Also is it 15kwh out on 150 or 1500?

    Id put it down to variance in the CT. It only .25 kWh a day of error



  • #9
    red bellied
    Registered Users, Registered Users 2 Posts: 358 ✭✭red bellied


    The bill was over two months for around 393kwh in total. I double checked earlier and calculated 376kwh from my stats.



  • #10
    bullit_dodger
    Registered Users, Registered Users 2 Posts: 2,596 ✭✭✭bullit_dodger


    https://www.boards.ie/discussion/comment/122162840#Comment_122162840

    Course variances generally work both ways. A some time in the future, you might be undercharged. They do tend to balance out over time unless you have a defective meter (yes, that has been reported here once on this forum before, so it does happen. No no idea of how frequent that happens though but I wouldn't think it's widespread)

    I'd tend to believe the esb meter over a CT clamp generally though.



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