Currently working on a project that includes the Si1145 lightsensor.
The Si1145 measures visible light and infrared light and then calculates the UVI from that, without measuring actual UVA or UVB levels.
According to Adafruit it is very reliable.
When i used it however, it seemed the visible and infrared readings always hung around 625 or were 0, while the UVI was always 0.
Now ofcourse I could have a faulty sensor, but some browsing on the internet showed that this was a common occurrence.
When I put the (adafruit) library next to the datasheet, at first glance I couldn’t help but get the impression the library had some shortcomingins that might well explain the erratic behavior.
After some searching I found a latched library that worked better……but even then, in total darkness the ambient light and IR light hung around 600, but at least in daylight I would get different values and even a UVI reading.
The latter though proved totally inaccurate, easily going up to 7 in overcast weather.
I will do some further digging in the code but for now I would not recommend this sensor