As discussed in the below post I am working on a project to measure excess, available PV power and use that power to automatically control a load.
I now have a working prototype using a PLC, with a Ladder program, that performs this function. The key is installing an Irradiance/Temperature Sensor at the PV array. The one I used is an Si-I-420TC-T made by Mencke & Tegtmeyer GmbH. Link to the sensor is below:
I am still working on the Project's documentation, so I am including a wiring diagram and an Excel spreadsheet which demonstrates the calculation to compute available excess power.
Look forward to the conversation,