I am monitoring house electricity consumption and PV generation in a 'type 1' system, and am interested in how much of the PV energy is used in the house, and how much is exported (not just the net import/export over a day).
I could not find an easy way to do this in emoncms; whilst it is easy to calculate the difference in power or energy between consumption and generation inputs, I could not see a way to consider just positive value of a generation-consumption (=export) calculation, for example.
The way I have worked around this is to put a simple if...else statement in the Emontx code (if PV power > consumption power, then export = PV power - consumption power, else export = 0) and assign the currently un-used emontx.power3 input (only 2 CT clamps in a 'type 1' system)) to send only positive values to node10_3 in emoncms (emontx on node 10). The resulting input can be processed in feeds as desired.
Martin
Re: Calculation of PV energy exported
That looks as good a way as any. You can send what data you like to emoncms as far as I know, but there's a limit of 66 bytes (33 integers) on the transmitted r.f. packet.