I run an Oregon Scientific WMR 200 and have had 3 UV sensors that also record sunshine hours, they are probably the worst sensors I have had the misfortune to own.
They usually cease to work after 12 - 18 months at a £40 a throw I'm not going to replace it again.
I may well try the temperature sensor in a jar, as described by Brian Hamilton author of weather display.
He recommends painting the base of the jar black, so it becomes a black body and gives full instruction as to how to set it up within weather display.