Is it possible to set up any cumulative summations on the IoTa? In particular, I have my integrator of energy usage ( int(power) ), can I set a variable Q_tot = Σ( int(power)_i) to track my total energy consumption (or production)?
You don’t need to integrate power to get energy. IoTaWatt stores energy in the datalog in Wh units. You can simply access that with Query or implicitely with Graph+.