Hold on to your hats boys this is going to be a wild ride.
I found a graoh in a Scientific American article showing panel output in % of panel rating vs. time of day. [ Specified attachment is not available ] [ Specified attachment is not available ]
This is for a 12 hr. day where the sun strikes the panel at 0 deg. at sunrise, perpendicular at solar noon and again 0 deg. at sunset. Because the sun will strike your panels at an angle greater than 0 deg. during any other length of day.
I have used this graph to show the panel output for your location with 10:30 sunrise and 2:30 sunset. The black area represents the power your panels will gather during this period.
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This picture represents the power your panel would gather on top of the mountain, assuming 8 hours of sun. (I have no idea how many hours you actually get as you haven't provided this or your location)
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Again the shaded area represents power gathered, in this case 8am to 4pm.
The maximum power gathered in all cases is about 70% of the panel rating, this take into consideration many variables
but is close to real world values.
Picture 1 shows an average of 68% of panel rating for 4 hrs. this times your panel rating of 3600 watts
gives you 9792 whrs of production in the valley.
Picture 2 shows an average of about 55% of panel rating for 8 hrs. giving you 44%hrs. this times 3600 watts
gives you 15840 whrs. of production on the mountain top.
Now taking into consideration voltage drop in the 2 cases using 100 ft of 2ga. aluminum in the valley and 1300ft on the mountain top and because voltage drop is linear with both amperage and conductor length I used an average of 68% of 32 amps for the valley and an average of 55% of 32 amps on the mountain top
the calculator shows a .89% drop for the valley so 99.11% of 9792 watt hrs would give you 9705 watthrs.
The calculator shows a 9.4% drop on the mountain top so 90.6 % of 15840 whrs would give you 14350 watthrs.
This shows about 50% increase in output by moving the panels to the mountain top.
Moving the panels would cost $1000 more for wire.
Adding 1800 watts of panels in the valley to get the equivalent output would cost 1800w X $.85/w =$1530 plus an extra or larger charge controller.
There are hundreds of variables which would change these numbers but this gives you a rough idea of what you can expect.