The video has 7 examples of electric producing PV Grid connected solar panel systems.  Also, there are estimates as to how much money each system produces each month.  There are examples for a solar system in California with 5.5 sunlight hours and about $.22 per kwh for the cost factor.  Also, there are numbers used for several other states like New York, Texas, and Nevada and Arizona.  One thing that everyone should realize is that even though you may live in a state where there is tons of sunlight, that does not always mean that you will save more money compared to someone living in a less sunny state.  The reason is it also has to do with the average cost of electricity.

Also, the hope is that with the visuals from the video’s solar system examples, you will be able to see what it might look like to have solar panels on your roof.

In order to calculate the maximum number of solar panels that will fit on your roof, you need to come up with the square feet you have available.  To make this equation simple, lets assume that you have 1000 sq. feet of space that you would like to place solar panels often referred to as solar cells.

Next, you need to do some calculations to determine the size of the solar panels you will be using.  One of the most common solar panels is 15 sq. feet per panel.  They are roughly 5 ft by 3 ft.  So, for this example, we will use this size solar panel, which if you are wondering is usually about a 175 watt solar panel.

If the Dimensions of the roof are totally square, lets say 33ft by 33ft, which would equal 1000 sq. feet, we can figure this out.

First, take one side of the roof which is 33ft long.  And, lets subtract 3 feet from this side, because we need to have some roof for workers to walk on the roof.  So really, if we did this to all sides, the area we have to work with is now 26 ft by 26 feet.  That would mean that all edges of the original surface area are now taken in by 3 ft for safety.  Here is a diagram of a 33x33ft roof taken in 3 feet on each edge:

And, when the area is re-adjusted for the 26’x26′ usable solar panels space, it is going to look like the diagram below.  And if you want to maximize the space, you can end up fitting 40 panels on the roof like in the picture diagram below:

Please note that if you end up using solar panels for your roof which are lets say 200 watt panels, the dimensions could be considerably different, and would skew the diagram and ideas presented above dramatically, so of course it is best to consult with a solar company to get the exact numbers.

solar panels covering a parking garage

One popular place for solar panels is starting to be the parking garage, or at least the roofs of parking garages. In fact, it is estimated that parking garages will become the most popular place for solar systems within the next 20 years for several different reasons.

One of the reasons that a parking garage makes such a good location for PV solar panels is due to the easiness of accessing the area for the actual installation. Many parking garages have open top levels for parking which also usually have unobstructed views towards the sun. Since shade is one of the worst things for a PV solar system, having no shade at all makes the solar electric systems much more efficient.  It will never change that maximum sunlight hours is key to the output of a solar system.

Another reason that businesses and universities are installing PV solar systems on top of parking garages is because it gives off a great show of interest in enviornmental awareness or “Going Greenness” to all of the people who use the parking garage. Having a PV solar system on top of a parking garage is a great way to prove you are going green.

A solar system mounted on a parking garage on a rack system

A third reason why the parking garage is becoming such a popular location for PV solar systems to be located is for cost reasons. When working on top of roofs, there is often the need to re-roof prior to installing the PV solar system. This is obviously very costly. But parking garages are usually built for the long haul, and often a Rack mounted solar system is installed, so the actual PV system will sit on a custom fabricated set of stands, which will last a lifetime when done properly.

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.