Negative measurements to distinguish consumption and production

    Hi all!

    I want to buy a Shelly Pro 1PM to measure the net power consumption of my apartment. Almost my whole apartment runs on the same circuit (apart from bathroom and stove), so the measurements produced by that sensor will capture the consumption quite accurately.

    I also have a solar panel on my balcony, which is on the same circuit, so the sensor will actually give me my net balance, i.e. consumption minus production.

    What if I go negative though, i.e. if there is higher production than consumption? Can the sensor produce negative power draw measurements? Is that even physically possible? The Plug S for example only produces unsigned values. Is there a way to know whether I'm consuming or producing 100 Watts at the moment, if producers and consumers are on the same circuit / same fuse and it's infeasible to observe every single wall socket separately?

    Hello muety,

    the Pro1PM is able to recognize whether it is currently being consumed or feed in. In the case of feed in, the sign is negative.

    However, it doesn't seem to measure very accurately. Mine has a deviation of about 9%.

    Because of the relay in the Pro1PM and the higher accuracy, I would recommend you to use an EM or 3EM.


    greeting

    SeRef

    Zitat

    Thanks a lot, very helpful! In the meanwhile, I am actually considering to use a fully-fledged three-phase power meter (like this one) instead of one or multiple Shellies 🤔.

    I have four Iammeter 3080T three phase meters installed for 8 months now. All working well and seem to be accurate. Cloud app is nice and can be used with Home Assistant.