Your A/C works by dumping heat outside, with help from the compressor/coil, collected inside via the refrigerant/coil(you can't make cold, only remove heat). So, the hotter it is outside, the less efficient it becomes. What color is the building? If it's a dark building, then you may benefit from moving it out of the sun side.
How much it will help is debatable. If you take a shaded temp reading on sunny side(close to unit, but not picking up heat being dumped or direct sunlight) and a reading on shady side, and it was say a 5 degree difference, then I would say it would be worth moving it. It will only be more efficient in the shade, but whether you will notice it in your utility bill is another question.
Easiest way to keep it efficient is to make sure the filter is clean and both coils are clean. If you have pets like cats/dogs, the filter and/or coil will get a soggy mat of hair
on it if not cleaned. Eventually if not cleaned, it will freeze up.