Hello, I'm using nodered to interface with a single phase meter configured for solar pv.  How can I retrieve the kw generated only for today?

Hello,

The daily kWh is not calculated based on the power value but on the total kWh value. You should perform specific operations when a new day begins.

Store the first and last kWh values of each day and calculate the difference at the end of the day.

For a tutorial on how to implement daily kWh calculation in Home Assistant, you can refer to the following video:

Daily kWh Calculation Tutorial

I think the nodered may also have the same logic.