Add another battery?

WOW - you guys are great - this many replies in such a short time ... I can be pretty conservative with my lighting, and I almost always take an ice chest with me for ice and meats - but I'm a freelance photographer and take the trailer out in the boonies for photoshoots.. I have a mobile hotspot for Internet, and shoot photos in the day and using my computer, process them in the afternoon/evening and upload to Dropbox almost nightly. I don't 'surf' the net, but sometimes those uploads take a couple of hours .. so it appears my main concern is the heater fan and computer useage. "IF" I were to go the Solar route, what would be a good size? I'd like it to be portable, so I can park in the shade and run the panels out to the sun. Would I also need to upgrade to an additional battery, or should the solar unit keep the one I have charged for usage each day? Thanks again for the input - it appears a solar rig would cost less than a battery upgrade and/generator!