HOW GRID INTERCONNECTED PV WORKS
Once your PV system is installed, you will enter into a “Net Metering” agreement with your utility company. Electricity produced by your PV system 
powers your home directly. Any excess electricty your system produces goes back into the grid through your meter, spinning it backward. At night, you draw electricity back in from the grid. At the end of the month you will only pay for the amount of electricity used that exceeds the amount produced by your PV system. There are two options for net-metering in Rhode Island. At the end of the monthly billing cycle, if you have produced more electricity than you have used, the excess can be credited to the following month, or you can be paid for it at the end of each month.
http://www.nationalgridus.com/narragansett/home/energyeff/4_net-mtr.asp.
ROOF, GROUND, POLE, OR WALL MOUNTED?
Solar panels may be mounted on your home or garage roof as long as there is enough unshaded space . If your roof is not the most ideal location, solar panels may be ground mounted on a rack which gives you the option of having a seasonal adjustable tilt to maximize electricity production. Solar panels may also be pole mounted which gives you the option of tilting or installing a tracker to keep your array directly facing the sun all day. This may increase overall production up to 30% here in New England. Wall mounting, also known as Building Integrated PV (BIPV) is another otption. Many other options exist such as pv roof shingles and bi-facial panels that absorb light on the front and back of the panel. Call for an appointment to see what options are possible at your site.