We are implementing the openenergymonitor transmitter, and were wondering whether there is a convention. Cutting through all the Active Power, Reactive Power, Apparent Power, we should get a figure of plus or minus watts. If the user turns the CT clamp round, this will be reversed.
Is there a convention that Import is positive, and export negative, or the other way round?
We can of course write software to cope with either - and then be consistent - but I was wondering if there is a convention?
I guess that if import meters have been “positive” for more than a century, then “export” would be a negative value?