Ask Slashdot: Home Testing For Solar Roof Coverage?

DudeTheMath writes "Here in the Sunshine State (Florida), solar should be a no-brainer. However, large oaks that require permits to trim partially shade my roof. I'd like to (inexpensively) 'pre-qualify' my roof for effective panel area. Googling for 'home solar testing' gets me equipment for checking the efficiency of an existing PV installation. Do any makers know what I can do on my own in terms of placing a few individual cells and, over a year, measuring and recording their output, so I can get an idea whether solar would be cost-effective for me?"