Not sure what you want to do.
If you want to lower to a certain fixed position in case the sun hits the sensor and up again if not, create 2 scenes (one for up and one for the lowered position) and trigger them based on the sensor reading.
Let me know if that is what you want and if you need help setting that up.
If you want the shade to position to be dependent on the light intensity, so the more light, the lower it goes, it is a bit more complicated.
One way to do this now id to create many scenes (one for each shade position) and trigger them based on the measuremed light intensity via logic boolean variabled. Just like johan suggests. Another option is to use some homeyscript.
But the best way to get it now is to use HTTP cards (there is a homey app for that) and use the PowerView Hub API. Don’t know how technical you are. I could make a guide for it If more people are interested. If you can’t wait to try, send me a PM so I can guide you via Skype.
I am thinking about extending the existing Homey Luxaflex PowerView app so you can set the position with a variable.
I am also thinking about adding controls for up / down, stop and tilt up/down (or in case of top/down shades the upper bar position). Just like the PowerView pebble remote.
This might need 2 homey devices per shade, because homey only supports up / down stop as controls.
In also this opens the possibility to use any homey connected switch to operate the shades directly.
Maybe this is s good place to ask how many people would be interested in such an extension of the app…