After ownership of property, the second important question is where to locate your solar system. Most property owners locate their solar system on the roof of their building. Some locate it on a field or on a yard close to their building. There are really two important criteria to satisfy when evaluating the location of solar system:
1) No shading: Is the roof (or the field) space where the solar system will be laid getting any shading or not? Ideally you want no shading on your roof (or whichever surface your panels are laid on). If there is partial shading for a small portion of the day that might be acceptable. In such cases, any solar installer should be able quantify the effect of shading using a site shading analysis tool.
2) The correct angle to the sun: Does your roof or property allow you to lay your panels with a slant such that they are tilted to be facing the sun for most of the day. This means you want a south facing tilt if you are in the northern hemisphere. And vice versa. A north facing tilt if you are in the southern hemisphere. Usually the correct tilt degree is equal to the latitude you are located on. In other words, a 90 degree tilt on the poles and no tilt on The Equator.
If you can satisfy the above 2 criteria, then the final criteria to satisy before going solar, would be the economics of your investment.