I've used all the tags, but when you look at the "HI" it follows the Rad. curve but is just a bit higher, when the curve starts back down so does it, so it's not a "ratchet" which sticks at the day high, I'm not sure it's of any value. For instance, yesterday the Solar Rad (peak) was 1031, the "HI" was 1035 and the last reading of the day was 3 while the HI was 7 - I may just pitch that column.
We live in the perfect place for solar, way south, lots of sun all year, even during the rainy season and the biggest incentive of all, our electricity is "dirty", erratic and nearly $.42 per KWH, so getting away from it and actually feeding back to the CFE makes sense. I don't know anything about solar so have been pulling out everything I can to see what the local solar folks can use as I learn.http://chapalaweather.net/Solar.htm