To know if my roof is convenient to install a PV array or a solar panel and then determine how these will make, in almost all cases (unless I’m in the open plains with nothing around) you need to know and draw a card sun.
Also have to know how much sun a particular site, you need a paper calendar.
The solar paper, better said solar diagram, is a graph in which is the path to the sun during the year and on which is superimposed on the profile of the horizon, composed of all the elements placed at a certain minimum distance from the point at conisderazione.
Well, to draw a diagram of the solar technology now comes in handy:
some simple applications for iPhone helps you find the position of the sun (or any other planet, star or satellite) at any time of the year simply by viewing the image captured by the camera.
I point the camera displays the image on the screen and this is represented on the path of the sun.
Applications and also there are many free; personally among many SkyView advice.
The correct and meaningful data interpretation should be left to a competent professional, who will draw the appropriate conclusions and guide you towards the most appropriate.