irekz:
With arduino + wifi shield. I have a real-time PV production and consumption data available on WiFi.
Would like to connect arduino instead of CT clamps to the battery storage system.
Just use a function to return the current current consumption, write one version that uses the WiFi data, and when the CTs come on line write a different version that uses the CT readings. You might also need a function to call regularly from loop() that drives the measurements/data collection regularly.
You could even wrap these functions in a library, then you'd substitute libraries when CT's are available, just have both libraries implement the same set of functions.