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.

Shade hitting solar panels is just plain ugly.  For the record, solar panels are happy when there is unobstructed sunlight hitting them.  When there is shade on solar panels, they simply do not operate at optimum efficiency. The hours of sunlight on solar panels is super important.

So, with shading in mind, do everything you can to make sure there is no or as little shade as possible on your solar panels.  Some people who are planning on buying a solar panel system build there future home with shading in mind.  This is a GREAT idea.  If you too are planning on building a home in the future, why not take some time and contact a solar installer and ask them what their opinions are on the best places for solar panels with regards to shade.

One common mistake that homeowners make with regards to solar systems and shadding is they assume they know exactly how the shade effects their property.  This is great that everyone feels they know how sunlight hits their “land” or “house”, but in reality, most of us don’t usually sit outside all day long throughout the year and observe how the sunlight falls down every minute of the day and take notes on it.  There are scientific shadding devices that solar people use that can callculate this instantly, and they are VERY ACCURATE on predicting shadding on a specific part of your house.  All types of lasers and things like that are involved.  So ask your solar installer about conducting a shading analysis prior to installing any type of solar system.

At the end of the day, if you can eliminate just 10% more shade that would otherwise be hitting the PV solar cells, then you will be increasing your energy production by another 10% at the same time.  This will payoff in many thousands of dollars over the lifetime of the solar system.

Solar panels come in a whole bunch of sizes or you might say they come in different wattages or watts.  One really common size/wattage is a 200 watt solar panel.  The physical size for one of these panels is roughly 5  feet long by 3 feet wide, and usually about 3 inches thick.  So, think of one of these panels being about 15 square feet.

What does a 1kw (1000 watt) system take up in square feet?  Well, that’s roughly 5 solar panels that are 200 watts each.  So, the math would be 5 x 15 square feet or about 75 square feet total for a 1kw solar system.

The Energy Production of one 200 watt solar panel:

This again will depend on the sunlight hours of the location that you are going to place the solar panels.  If for example you have 5 sunlight hours per day per year in your location, you could expect each panel to produce about 1 kilo watt hour per day in direct current.  And of course if you had 5 panels, that would equal about 5kwh/day in direct current.  There is going to be a slight energy loss when the energy is converted into alternating current(AC) so after that factor, you would have about 85% of what you started with give or take a little either way.

Here are some pictures of what these solar panels might look like.  They are examples of 200 watt panels:

GE 200 Watt

Sanyo 200 watt

How many hours of sunlight where you live?

Here is some data on US Cities Sunlight Hours.  This data is the average number of sunlight radiation hours per year:

• Birmingham, AL  has average sunlight hours of  5.2  per day
• Phoenix, AZ          has average sunlight hours of 6.6  per day
• Tucson, AZ            has average sunlight hour of  6.7 per day
• Little Rock, AR    has average sunlight hours of 5.0 per day
• Los Angeles, CA  has average sunlight hours of 5.5 per day
• San Francisco, CA has average sunlight hours of 5.3 per day
• Sacramento, CA  has average sunlight hours of 5.5 per day
• Bakersfield, CA has average sunlight hours of 5.7 per day
• Denver, CO has average sunlight hours of 5.5 per day

• Grand Junction, CO has average sunlight hours of 5.7 per day
• Colorado Springs, CO has average sunlight hours of 5.5 per day
• Hartford, CT has average sunlight hours of 4.4 per day
• Bridgeport, CT has average sunlight hours of 4.4 per day
• Wilmington, DE has average sunlight hours of 4.5 per day
• Jacksonville, FL has average sunlight hours of 4.9 per day
• Miami, FL has average sunlight hours of 5.1 per day
• Tampla, FL has average sunlight hours of 5.2 per day
• Atlanta, GA has average sunlight hours of 5.0 per day
• Savannah, GA has average sunlight hours of 5.0 per day
• Augusta, GA has average sunlight hours of 5.0 per day
• Honolulu, HI has average sunlight hour of 5.5 per day
• Boise, ID has average sunlight hours of 5.0 per day
• Chicago, IL has average sunlight hours of 4.4 per day
• Rockford, IL has average sunlight hours of 4.5 per day
• Indianapolis, IN has average sunlight hours of 4.6 per day
• South Bend, IN has average sunlight hours of 4.4 per day
• Des Moines, IA has average sunlight hours of 4.8 per day
• Waterloo, IA has average sunlight hours of 4.6 per day
• Topeka, KS has average sunlight hours of 4.9 per day
• Wichita, KS has average sunlight hours of 5.2 per day
• Lexington, KY has average sunlight hours of 4.8 per day
• New Orleans, LA has average sunlight hours of 4.9 per day
• Baton Rouge, LA has average sunlight hours of 4.8 per day
• Portland, ME has average sunlight hours of 4.6 per day
• Baltimore, MD has average sunlight hours of 4.6 per day
• Boston, MA has average sunlight hours of 4.5 per day
• Worcester, MA has average sunlight hours of 4.5 per day
• Detroit, MI has average sunlight hours of 4.3 per day
• Grand Rapids, MI has average sunlight hours of 4.2 per day
• Minneapolis, MN has average sunlight hours of 4.6 per day
• Deluth, MN has average sunlight hours of 4.5 per day
• Rochester, MN has average sunlight hours of 4.5 per day
• Jackson, MS has average sunlight hours of 5.0 per day
• St. Louis, MO has average sunlight hours of 4.8 per day
• Kansas City, MO has average sunlight hours of 4.9 per day
• Billings, MT has average sunlight hours of 5.0 per day
• Missoula, MT has average sunlight hours of 4.4 per day
• Helena, MT has average sunlight hours of 4.7 per day
• Omaha, NE has average sunlight hours of 4.9 per day
• Las Vegas, NV has average sunlight hours of 6.4 per day
• Reno, NV has average sunlight hours of 5.8 per day
• Concord, NH has average sunlight hours per day of 4.6
• Newark, NJ has average sunlight hours per day of 4.4
• Atlantic City, NJ has average sunlight hours per day of 4.6
• Albaquerque, NM has average sunlight hours per day of 6.3
• New York, NY has average sunlight hours per day of 4.5
• Syracuse, NY has average sunlight hours per day of 4.2
• Albany, NY has average sunlight hours per day of 4.3
• Buffalo, NY has average sunlight hours per day of 4.1
• Charlotte, NC has average sunlight hours per day of 4.9
• Fargo, ND has average sunlight hours per day of 4.6
• Oklahoma City, OK has average sunlight hours per day of 5.3
• Portland, OR has average sunlight hours per day of 4.0
• Harrisburg, PA has average sunlight hours per day of 4.6
• Pittsburgh, PA has average sunlight hours per day of 4.2
• Bradford, PA has average sunlight hours per day of 4.2
• Philadelphia, PA has average sunlight hours per day of 4.3
• Providence, RI has average sunlight hours per day of 4.5
• Charleston, SC has average sunlight hours per day of 5.0
• Rapid City, SD has average sunlight hours per day of 5.1
• Memphis, TN has average sunlight hours per day of 5.1
• Chattanooga, TN has average sunlight hours per day of 4.7
• El Paso, TX has average sunlight hours per day of 6.3
• Austin, TX has average sunlight hours per day of 5.2
• Houston, TX has average sunlight hours per day of 4.7
• San Antonio, TX has average sunlight hours per day of 5.3
• Waco, TX has average sunlight hours per day of 5.3
• Dallas, TX has average sunlight hours per day of 5.3
• Salt Lake City, UT has average sunlight hours per day of 5.2
• Burlington, VT has average sunlight hours per day of 4.3
• Richmond, VA has average sunlight hours per day of 4.7
• Lynchburg, VA has average sunlight hours per day of 4.9
• Seattle, WA has average sunlight hours per day of 3.8
• Charleston, WV has average sunlight hours per day of 4.3
• Madison, WI has average sunlight hours of 4.6 per day
• Cheyenne, WY has average sunlight hours of 5.3 per day

Sunlight and solar panels go hand in hand.

It’s not a big mystery.  You could probably ask any homeowner who has a solar system what the one thing is they would wish to have more of, and everyone would say more hours of sunlight.  The reason is simple: Solar panels work when the sun is shining on them, period.  This is why solar sunlight hours are key to the overall success of a PV installation.

Since sunlight is such an important part to increasing the energy output of solar panels, use this knowledge to your advantage.  Don’t make the biggest mistake others have made when you are determining where to put your solar system, make sure to put the panels in a spot either on the roof or on the ground which gets the most sunlight hours.

For many people, there might be several good positions for a solar system on the property or roof that is being considered.  And for all of these people, there is going to be one spot that is going to allow the solar system to produce the most energy, which should be the goal.

There are a few different ways that you can calculate the sunlight hours for different spots on your property, one way would be to sit outside and keep track by viewing the sun over the course of several days, and preferably over the course of different months of the year.  Sunlight hours will always vary depending on what time of year(more sun in summer, less in winter, etc…)

But I don’t know about you, this is method is just not efficient and usually ends up being less than accurate.  So here is another more scientific approach.  Use a device that is called a Solar Pathfinder, or a Sun Eye device.  This is a small remote control looking thing that will allow the person using it to take an accurate reading of a certain point on your property to determine exactly how many sunlight hours exist for each month of the year.  There are lasers and other metrics involved that are a bit complicated to explain, but the device can read the surroundings(like trees and shadows) and give you the numbers you want.

Now of course, most people don’t have one of these devices since they can cost a couple hundred dollars, but for sure a local solar professional will have one, and for a small fee, should let you use it for a few minutes.  The cost of getting this reading will pay off 1000 times, so just do it.

Some other great advice would be to make sure that future sunlight will not be obstructed from things like new buildings, new garages, growing trees, or other objects which might get in the way of the sunlight hitting the solar panels.  It is very sad to know that right this minute people are losing hundreds of dollars across the country in energy they could be producing simply because a tree has grown and is now blocking the sunlight that could be hitting the solar panels they installed a few years ago.(but its very true) Don’t fall into that trap, and make sure to clear all trees that may block the solar rays.

If you would like to get the sunlight hours for different cities in the United States, you can see the solar radiation sunlight hour data here.

What is the best option?

Here is another decision that is usually answered rather quickly and early on in the solar decision making tree.  First of all, there is a major distinction that needs to be clear about PV solar systems.  One option is to install a “Grid Tied” system.  That means, the solar system will be connected to your utility company’s network(the electric panel).  The other option is to be “Off the Grid” which would mean the system does not connect to your electric panel(imagine you live where there is no electric company, i.e you don’t have an electric bill)  There are quite a few variations, but that is the general idea.

Why would you want a Grid Tied System?

People chose grid tied systems for many reasons.  Here are a few: cost, net-metering, incentives, less maintenance, more installers know how to install them.

Cost

Grid Tied systems have the following costs:  panels, inverters, disconnects switches, wiring, mounting hardware, labor to install, permits if necessary(usually a nominal fee, nothing too big)

Net-Metering

The net metering option allows a “grid tied” system to connect to the grid and put excess unused electricity back into the grid, otherwise it would be wasted.  This is a benefit because the owner of the system can effectively “sell back” their electricity if they don’t use it.  This doesn’t mean the electric company will be writing you a check everyday, but they very well may give you a credit on your electric bill if you have given them more electricity than you have used for a particular month.

Incentives

In some states and areas, solar incentives are only eligible for “grid tied” systems.  That is something you will want to check with your local solar professional.

Maintenance

Grid tied systems are by and large, much easier to maintain.  When installed correctly, they can run on their own for an indefinite amount of time.  If you are having to tweak and mess with a grid tied system after it has been installed, than the installation was not done correctly.  These are no hassle systems after they have been implemented which is one of the major reasons grid tied systems are so popular worldwide.

Why Would you want an Off Grid System

People tend to chose off grid systems because they are not near utility power, the utility company is not reliable(3rd world countries), want a sense of energy independence, want a backup supply of electricity if the power goes down, and many more.

Utility Power is Far Away

If the local utility lines are so far away that it is too expensive to pay for new lines, an off grid system might be a good match for you.

Not Reliable Utility Company

Some people on the planet have such horrible times actually receiving electricity from their local or government utility company that it simply is not an option to rely on that, this makes off grid solar a good option.

Energy Independence

If you really put a value on supplying your own energy all of the time, and want to tell the utility company to disconnect your lines, off grid solar could be perfect for you.  That is what it allows you to do.

Backup Power

There is an “off grid” but still “on grid” hybrid way to this too.  If you wan to be connected to the utility company, like the “on grid model” but still want to have a guaranteed source of power if the utility power ever goes out like from a hurricane.  You can create a hybrid solar system.  This would actually connect to the grid, but would have batteries which would store power too.  This way, if the power went off, you would still have electricity in your batteries to use., and the sun to generate more power over the coming days.

You can Also Build Your Own Solar Power

Here is some information on how to do that

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.