The best advice anyone can give you over this public bulletin board is to seek out an electrical contractor with certification in photovoltaic systems.
With that out of the way, a lot would depend on just how much of a "do it yourselfer" you are. I have seen PV module array mounts made out of old aluminum storm doors, steel hinges, old bed frames, pressure treated lumber, and stainless steel bolts that are still in operation after several huricane seasons in the South East coastal region of America.
Wire size and type is a critical issue. UL listed ratings on fuses and disconects. There is a National Electrical Code(NEC)that will dictate this.
Keep in mind that, the lower the nominal voltage the higher the amperages and the bigger the wire. You will have to choose a nominal voltage for the PV array. There are so many varibles that will decide this. Some examples would be - how you plan to use the power. On grid or off grid? The type(s) of load placed on the batteries (if used).
Lets imagine an off grid cabin. The load is mostly for lighting at night and possibly a two way radio along with a radio/cd-player for entertainment. The yearly average, equivilent full rated charge, for a given region, from the PV array might be 4 hours on sunny days of course. The PV array is wired for 12 volts nominal. As you stated 80 watts total PV array.
80 watts / 12 volts = 6 amps,
6 amps x 4 hours = 24 amp hours a day.
(A little more in summer a little less in winter).
To size a battery for general purposes without knowing its full entended use, take the amp hours availible in a day and multiply by five. Thats 20% of full battery capacity.
24 x 5 = 120 amphour battery at least.
Being in a remote cabin used only for days or a week at a time, I would go way larger than 120 bacause they have a lot of time to re-charge when no one is there using them. A lot depends on how they will be used.
As for wire size, a lot depends also on how far away the PV array is from the battery. If within 50 feet or so use #10 awg (American wire gauge).
#10 awg is legaly good for 30 amps but with low voltages over long distances, voltage drop is an issue. Fuse with a 10 amp fuse rated for at least the PV modules open circuit voltage. Also #10 awg is as big a wire as one can use under a screw typr terminal, anything larger requires a mechanical lug.
Hopfully you are not in a big hurry and you will take the time to research these and other things concerning electricity, electrical wiring, and photovoltaic systems if you plan on doing it yourself.
http://www.homepower.com/index.cfm
http://www.houwire.com/catalog/technical/article310.asp
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/
http://www.dsireusa.org/index.cfm
I hope something I have written here helps.
Good luck to you!
