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Another take on SolarEdge inverter reporting accuracy

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  • Another take on SolarEdge inverter reporting accuracy

    Hi! Great forum, first post here. I have an SE5000 inverter in Europe, and I've been using an OpenEnergyMonitor setup since almost the beginning. It's fairly usable, a bit meh reporting web interface (EmonCMS), and I'm looking for alternatives. It's sampling generation and consumption using a small wall transformer as voltage sensor and clamp current transformers for current. I started looking around, and discovered that via a firmware upgrade, I can enable the Modbus over TCP protocol on my inverter and can poll for SunSpec data on it any time. It's great, provides a lot of info, including total generation and also instantaneous DC, AC values, heatsink temp, etc. Now, on to the weirdness. Obviously I'd like to see some consistent, accurate information on our consumption and generation. I checked a full day, and have collected the following generation data:

    1. SolarEdge portal: 19.3 kWh
    2. Inverter, night to night kWh difference: 19.3 kWh
    3. Inverter, sum(Watts queried each minute once) / 60 / 1000: 18.863 kWh
    4. OpenEnergyMonitor emonTx 3.4: 18.5 kWh

    So the cumulative energy values are the same for the portal and my inverter. The energy calculated from the instantaneous values is less by about 2.3%, and what my OEM shows is less by about 4.3%. Now, as the saying goes, if you have one clock, you can tell the time. If you have a few, you never know... Exactly like that. Which is the most accurate? Did anyone arrive at a conclusion? The OEM is sampling instantaneous values over 20 AC cycles or so (calculating true RMS), each 10 seconds. It should be pretty accurate, if the sensors are accurate. But I just don't know...
    Last edited by kobuki; 05-05-2019, 09:50 AM.
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