Here is another question that everyone wants to know.  How many panels can get up there on the roof?

Of course the answer is different for each home.  But, it is relatively easy to get a good idea by doing some simple math that anyone can do on their own.  The average solar which is either 175 watts, or 200 watt panels is about 5ft by 3ft.  So that is about 15 sq. feet per solar panel.  These actual numbers are a tiny bit larger than the most common sizes, but they work well for rough measurement purposes.

If you have a roof that faces the south(which is great for getting solar radiation in the northern hemisphere) and that roof has dimensions of 30ft x 20 feet, we can get an answer.  If the 30 ft is the width, and the 20 feet is the height side(meaning the 20 foot side rises to the top of your roof) then you could easily get 3 different rows of solar panels on that roof. Look at the diagram below which will represent the roof

<-30 feet this way for the roof->

X X X X X X X X

X X X X X X X X      } 20 feet up and down this side for the roof

X X X X X X X X

So if each X is a solar panel, there is more than enough room for 24 panels.   This would even leave 2 1/2 feet of space on the top and bottom, and 3 feet of space on the sides.  It is best to have some space around the outside of the panels to work with, also many local building codes require space around the solar panels for the fire department to have for walking space in the event that a fire does happen.  ***Most important, make sure to check if there are any non standard building codes in your area.  A local solar professional should be able to help you out with this type of question.  But, be wary if someone tells you that you should put panels all over the roof, and completely cover it, that is not a good idea.