If there are obstructions at your planned solar system site, you will need to identify  at what point during the day the obstructions are most likely to occur.

 Anything that is due south is a major problem, as this will be the position of the sun when the intensity of the sunlight is at its highest. Core power generation occurs between 9 a.m. and 3 p.m. If you have shading before 9 a.m., or after 3 p.m., you will lose about 20 percent of your capability - or around 40 percent of your capability if you have shading both before 9 a.m. and after 3 p.m.

During the winter, the difference is not as great. If you have shading before 9 a.m. or after 3 p.m. during the winter, you' will probably only lose around 10 percent of your generating capabilities.

 If you have shading during your core power generation times, you will need to give serious thought as to whether you should continue with your solar installation at the proposed site, since the performance of your solar system will be substantially compromised. If you have no alternative sites to consider, it may be more to your advantage to investigate other energy options, such as wind power or fuel cells, either instead of using solar, or in combination with a smaller solar electric system.

 Alternatively, if obstructions occur for only part of the day - such as during the morning or during the afternoon, you may consider increasing the number of solar panels for your system and angling them away from the obstruction in order to maximize their collection of sunlight during the unobstructed parts of the day.

Keep in mind that even partial shading can knock out the entire string of panels unless you have a ssystem with micro-inverters. Losing an entire string will significantly affect performance of your system. 

The final option, if there are obstructions, is to use a solar tracker that will move with the sun’s movement in order to improve the efficiency of the solar panels throughout the day.