Composition is spot on,thirds all the way,power station just off center.
Exposure--depends what your after.This works fine and its a good "as is" shot. A longer exposure would give you more light ppossibly bringing out the yellows in the field.This would also "stretch the clouds" which a lot of people like.
To keep the clouds as is a NG filter might be used to bring down the light from the sky allowing to balance the flowers--or my prefered methord, take your meter reading from the sky,then from the field then meet half way .
Focus about a 1/3 into image and set to area focus.(always use manual focus on camera and lens)
My way isn`t neccesarilly correct,just the way i do it,works for me