A: There are a few basic factors that landlords and home owners can initially evaluate to determine whether or not the installation of a Photovoltaic System on a roof top is feasible. These factors are listed below:

a. The ability of the construction of the roof to withstand the Photovoltaic system load (Photovoltaic modules, including the mounting system (the system that will support the PV modules). Roughly speaking, the weight of a system can be calculated if you multiply the number of modules x 20Kg. This will give you an estimate of the total system weight, including the support system, +/- 15%.
b. The orientation and inclination of the roof. Flat roofs will normally not be an issue, as you can tilt and turn the support system to the optimum angle and azimuth. For inclined roofs, you usually have no other option but to follow the existing inclination and azimuth. Have in mind that depending on your location the optimum angle and azimuth may differ. For Cyprus, the optimum angle according to Cyprus’s University research in this field is 27o,whereas the optimum azimuth is 180o degrees South.
c. The available area. Someone must take into account that an area of approximately 2m2 per Photovoltaic module is required to accommodate a photovoltaic system on an inclined roof, whereas 3m2 are required on a flat roof.
d. The existence of obstacles and shading. It is well known that Photovoltaic modules will be highly affected by shading and that their performance will dramatically decrease in their presence. This is what makes the selection of the location and layout of the pv system a hassle to installers as they will need to minimize this effect. As a rule of thumb, pv systems must be shade free starting at 09.00 am to 15.00pm, during which time approximately 80% of the total day yield will be produced. In addition, an obstacle is said to have no effect on a pv module if it is located 2 times its height away.