[hornychz]

This seems very interesting! I'm more inclined to a modification of the formula, than your previous suggestion, mostly because this way we keep the results with one decimal place.

It will be interesting, if we could have something like a table, to adjust the formula, considering the absorbing of the cover, in factors of, say 5 to 30%

You are right, it would be universal solution for everybody. My formula is useful only for the case we don´t use any cover. And if anybody wants to use it, he has to add switch negative number off. For example:

Code:

#if UV_Sensor == 1    
        // --- UVM-30A  on Unit1
        IndiceUV = (((ADC1 - 135.0) * 11.0) / 1024.0) ;
          if (IndiceUV <= 0) IndiceUV = 0;
      #else
        IndiceUV = 0;
      #endif

Exactly now, I'm testing a new simple and very low cost housing, for the the Solar / UV sensor. In this implementation, the UV sensor is covered with just a very thin film of clear epoxy resin (liquid epoxy, two components - long cure time). Later I'm planning to add a very thin crystal glass over the PV cell and the UV sensor (epoxy resin don't resist for a long time when directly exposed to hail)
I will gonna try your formula with it.

It's very important for me, once you have any conclusion, publish it, please. (The cover of my box I am very disappointed.)

How your readings are comparing with other nearby weather stations? (Supposing you are having a clear day without clouds in a large area)

New formula is only 2 hours old But I always compare my measurments with the meteo station in Hradec Kralove, it's very authoritarian station. And my UV Index measurements has to be correct. because I don't have any cover on my sensor and the measured voltage from it with the calculated UV Index I compared with datasheet.