The most important thing is that the inverter is in a shaded spot. Direct sunlight will reduce its lifespan. A cool garage is best.
The installer should also try to place the inverter as close to the meter as possible - to reduce voltage drops (and efficiency losses).
However, if you have to choose between a shaded location and being close to the meter, being shaded is more important.
Your installer can make up for a larger distance to the meter by simply using thicker wire to reduce voltage drop. The loss in this cable should be less than 1%.