The quintessential question is how long will it take to break even on the investment in a PV solar system.  This is one of the primary financial questions anyone interested in a PV system should be asking and evaluating.  There is no set answer as many variables play into the equation, but in Colorado the range is between 3-7 years for a system on a commercial property (added tax benefits like deprecation of assets help) and 7-11 years for a residential system.  Some of the variables affecting price and payback are: Installing a larger system usually will cost less per PV kilowatt due to economy of scale; multi-directional roofs add complexity and potentially some cost; specialty systems that deal with some shadowing issues could add cost or extend payback time; A ground mount, while typically more efficient will cost more than a roof mounted system due to the need to build a structure to mount to; Older homes or commercial properties with electrical systems that do not meet current safety standards may add cost to the installation of a solar system.  The best way to determine what the ROI (return on investment) would be is to have a solar PV installer provide an accurate bid to build an appropriately sized system for your desired address.