I see this thread is marked as "resolved" but there is no concluded response.
Is there any possibility to calibrate shellyEM from the software interface? It would not be too difficult to add something like that in the firmware.
(like a correction factor percent in format +/- 0.0% for each input voltage, current1 and current2)
For example i get different readings for the current when switch the transformer current.
This error multiplied with the voltage reading error, adds a lot of error to power/energy log.
I have a PZEM004T and this has a very good precision measured with calibrated DM.