108 volts at the top of the well while running the 1/2hp pump.

softdown

Thinking I had 118 volts before connecting the pump. The 1/2hp pump consumes 1100-1300 watts while running. 

108 volts is a low measurement and the pump is another 100' down the well. However....I believe that I have read that well pumps are designed to run on lower voltages....such as this.  

Is there a problem?

I think that I can push up the voltage of my Outback inverter. Sometimes I consider doing that since many of the shops wire runs are quite lengthy. 

Estragon

I think grid voltage regulation is ~ +/-10%, so 108v is at the low end of that. Low voltage means more current in the pump, which while it may be okay, can't be a Good Thing.

Assuming doing so wouldn't overvoltage anything nearby, putting the voltage up a tick or two on the inverter might not be a bad idea IMHO.

jonr

Franklin allows  a 5% wire voltage drop running at maximum nameplate amps.   Plus, I assume,  5% voltage tolerance in the unloaded supply (or maybe 10%).  So 120 * .95 *.95 = 108V is OK.  But with the 100 extra feet and probably not at nameplate amps, you may be slightly out of spec.

You could throttle the pump a little to reduce amps.