Why due East/West and not angled to the north?
During the year the location that the sun rises and sets change every day. It’s got to do with the tilt of the earth’s axis, which give the seasons. All those high school stuff. So what happens is that in middel of summer the sun actually rises in the south east in some places and sets in the south west. So this is not a fixed thing. It all depends on your location, how far you are from the equator and all that.
The best might be a picture, but a live picture is even better.
On the site http://suncalc.net/ you can go play with this. zoom into your location. Set the date to 24 Dec. and play with the timeline. Now set it to 24 June and play with the timeline again. Check where the sun rises (yellow line) and sets (red line).
Here I picked Struisbaai (the most southern point in SA)
Dec 24
vs Jun 24
So due East/West is a better avg. for the full year, trying to get the longest sun time that you can and leaving the batteries for when the .