I’m going about a slightly different route for cloud detection.
I am estimating the expected solar radiation for a non-cloudy day for a given lat/long and elevation.
Top two are two different estimates of solar radiation.
3rd is Solar Zenith, the lowest number is when sun is highest in the sky (solar noon)
The last is the measure solar radiation on the Tempest.
This is a work in progress. I have not had a non-cloudy day in weeks so it is very difficult to check my assumptions, but I think my 1st assumption is more accurate if not a little high. Once I get a full sunny day I can adjust.
I am currently performing the calculations in Node-Red and then sending to MQTT for data capture. Once this is more perfected it will be incorporated into WeatherFlow2MQTT for Home Assistant.