set up an alternate energy source or backup generator - no matter how many PV panels you have, they will not operate without sunlight! There are also choices to make regarding panel type and mounting. Roof-mounting can generally accommodate more panels, with their size and weight supported by the building.

Sun-tracking mounts hold between 16 and 20 panels for every tracker. Remember, there is no "ideal" number of panels: if you can afford it, install the maximum number for winter's darkest days. Otherwise, start with a small installation and expand it as your electrical needs grow or when you have more budget. However, it is important to include possible expansion routes when planning your system installation to reduce future costs (and headaches).