Unusable values of P1 Devices Usage and Return

[pgielen]

When connecting P1 hardware to Domoticz, it creates (among others) a Usage Device and a Delivery Device. My guess is that they use the values for current delivery and current usage provided by the smart meter. However, there is something strange in the way these values are calculated, which makes the information of these devices useless.

I'll try to explain why. On the smart meter, the current power is shown as a positive value if more power is used than generated, and a negative value if more power is generated than used. This is also the case in the Domoticz Electricity Device. It doesn't show you exactly how much power is used or generated, but at least it's possible to calculate how much it will cost.

The Usage and Return Devices in Domoticz work differently. The Usage Device shows the current power used minus the power generated ONLY if more power is used than generated. In this case, the other Device (Delivery) is 0, as if the pv-panels are not delivering power.

If more power is generated than used, the value of the Delivery Device shows the generated amount minus the power used, but the Usage Device show 0, as if no power is consumed.

This is confusing. If, for example, the oven in my kitchen is on and uses 2kW and the pv-panels are delivering 2kW at the same time, the devices will show:

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Current consumption: 0 kW
Current return: 0 kW

If the oven is on and the pv-panels are delivering 1kW, the Devices will show:

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Current consumption: 1 kW
Current return: 0 kW

If the oven is on and the panels are delivering 3kW, the result will be:

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Current consumption: 0.000 kW
Current return: 1 kW

But if the oven is off and the panels are delivering 1kW, the Devices will also show:

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Current consumption: 0.000 kW
Current return: 1 kW

This of course makes the data in both devices of little use, because you can't tell how much is actually being used or generated. Could be that the smart meter is not even capable of sending these values, since it only measures the amount of energy flowing by and its direction. Wouldn't it be better to make a new Device that calculates real power usage by reading data from both the smart meter and the solar power inverter?

[FireWizard]

Hi,

I think the smart meter does exactly what it should do.
If you don't have solar panels, so nothing is delivered to the grid, you have only an indication of what you consume from the grid.
The delivered power remains 0.
Example: Your oven uses 2 kW, then you will see that you consume 2 kW.
But if you have solar panels and your solar panels produce 1 KW, you use the 1 kW for your oven but you need an additional 1 kW in order
to deliver 2 kW to your oven. So what you will see is that you deliver 0 kW to the grid and consume 1 kW from the grid.
If you produce 2 kW all the energy is used for your oven and you consume 0 kW from the grid and at the same time you deliver 0 kW to the grid.

So if your Usage Delivery shows 0 kW it indicates only that you currently deliver 0 kW to the grid, and that you probably consume more from the grid, but it does not give you an indication of what your solar-panels produce. That is another thing.

Remember: The smart meter indicate the current you use from the grid (then you pay) or the current you deliver to the grid (then you get money back), but it is technical impossible for the smart meter to do both. As long as current doesn't pass the smart meter, the smart meter will not see it.
If you want to see the production of you solar panels you should connect to your portal of the solar panel manufacturer/supplier.

Regards,