Hi Bryan,
Thank you for your reply, The PV system is grid tied (connected to the grid) it is a MCS approved installation so the entire PV system must stay as it is and not be modified it has to be connected to the grid to work. However the AC output from the inverter is a 2.5 T&E cable it is possible to separate the live conductor and fit a coil around it to monitor the current. The AC output from the inverter feeds via a 2.5 T&E through a meter ( this measures the power generated by the PV system) then it connects to a spare way on the consumer unit. PV system max output is 3.6 KW, I'm not sure what mppt is?
If you need any more info please let me know.