Perhaps in an effort to keep your shadow from moving... you don't get to your right side in the backswing? I hate hitting from a shadow too, but I don't notice too much difference really.
My Shadow - Page 2
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I just came from the range to see if I find a solution here. However my problem is totally opposite. Hit the ball 100% better when I can see my shadow; I don't have to even look at the ball. I just look @ my shadow because I can see my swing specially when I'm backswinging. I can see my club well set at the top. Then in the downswing, by looking at it in my shadow it helps me make a nice round dropdown that prevent me coming over the top. When I have no shadow it gets very difficult for me to hit long irons all the way down to my driver. I also swing very well when I can see myself on the mirror. So what I do is practice @ the range @ night so I can select a slip that the light comes from the front ( to overcome my problem). When my swing goes south I jump to a slip that the light comes from behind. I take like five swings repeatedly looking at my shadow then I close my eyes and take a couple more to imprint the feeling of a good swing. Perhaps you should do the opposite.
I hit the ball better when I can see my shadow and it is straight behind me (behind the ball) or straight ahead of me (toward the target). I can see my swing in my peripheral vision and I usually hit some really good shots. I usually take practice swings so I can see my shadow this way before I address my ball and hit a shot.
But I hate when my shadow is over the ball and it moves off the ball in my backswing and then back onto the ball in my downswing. I guess I just have to make it a point to concentrate on the ball and not the shadow.
If it is that big of an issue, then just always hit your ball into shadows so you don't have to worry about it.