To minimize voltage drops in the solar system as a whole you should make the distance from the inverter to the meter as short as possible to minimize transmission losses, even if this means the distance from the panels to the inverter is a lot longer.
In most grid connect systems you have a higher voltage coming out of the panels than out of the inverter.
The voltage out of the inverter is 240AC and the voltage from the panels is usually 300 to 600V DC.
If you want to be sure that your solar system will operate reliably, then the voltage drop between the inverter and your grid connection needs to be less than 1%.
Why? To ensure that the inverter has enough excess voltage to be able to push its energy onto the grid. If you have a long run of cable your solar expert should calculate the size of the cable to compensate any voltage drop from the grid.
Of course the best way to minimise voltage drops in your solar system – which will maximise your power output and maximise the return on investment – is to use cables that are as thick as practicably possible. The thicker the cable, the lower the voltage drop across the cable.
Typical wire thickness (measured in cross sectional area – millimetres squared) for the DC cables that run from the panels to the inverter is 1.5mm², 2.5mm², 4mm², and 6mm². If you want to minimise losses you should use at least 4mm².
Believe me some of the large and super cheap solar installation companies want to save every last cent on every install and will try to get away with the 1.5mm² wire!
As for the AC cable, i.e. from the inverter to the meter, don’t go smaller than 6mm² and if you have to place your inverter more than a few metres from the meter then go thick enough to keep the losses in that wire less than 1%.