START A PETITION 25,136,189 members: the world's largest community for good
START A PETITION
x
2,615,889 people care about Environment & Wildlife

Is Your Home Ready For Solar Power?

Is Your Home Ready For Solar Power?

Written by Bill Ehrlich

Before anyone installs a solar system on their home or property, the question first crosses their mind, “Do I have a good site for solar?” Although designing a great solar system requires expertise, figuring out if you have a good solar site is really simple. Many solar installers will offer free site assessments but it doesn’t hurt to take a look for yourself. The three basic factors to look for when determining whether you have a good solar site are:

1. Orientation
2. Tilt
3. Shading

1. Orientation

“Orientation” simply means the direction your solar system is facing (i.e. north, south, east, west). Here in the northern hemisphere, the basic design rule is that you want to point your solar modules due south. In the southern hemisphere, it is opposite so there they point their modules to the north. If your house has a big south facing roof, that bodes well for your future solar installation. Even if your roof faces southeast or southwest you will only lose about 5-10 percent of the production you would achieve from due south. If your roof face is pointing east or west you will lose 15-20 percent of the production you would obtain with south facing modules so may want to consider a ground mounted system in that case.

sunpath.png

2. Tilt

The “tilt” of your solar array is the angle between your solar modules and the ground. Solar modules at a tilt of 0 degrees would lie flat on the ground (i.e. horizontal) while a module at 90 degrees would be straight up and down (i.e. vertical). Since the sun’s path changes throughout the year and your modules produce the most electricity when hit directly by the sun’s rays, it is best to have your modules tilted at an angle in-between 0 and 90 degrees. The optimal angle to tilt your modules is equal to your latitude in the northern hemisphere. Chicago, Ill., is at 42° N latitude while Dallas, Texas, is at 33° N latitude which means a solar module in Chicago should be tilted at 42° while a module in Dallas would perform better over the year tilted at 33° (see diagrams).

lat-long-us-map.jpgtilt_and_orientation_angle4.jpg

Solar-Array-Tilt-Angles-300x141.jpg

If the solar module is going to be fixed throughout the year and you want maximum overall production, set your solar module tilt angle to your latitude. If your solar module is movable for seasonal variation you can achieve higher production by raising the module more towards vertical in the winter and laying it more flat during the summer (see diagram).

array_orientation.gif

Normally you will install your solar system flush with your roof so you will not be choosing your tilt angle unless you are installing a ground or pole mounted system. If your roof is not tilted at the same number of degrees as your latitude in the northern hemisphere, don’t worry; the loss in production due to small tilt variation is minimal. Here is a chart that shows you what percentage of optimal production will be achieved based on different orientation and tilt angles for a site at 35° N latitude.

3. Shading

Is your potential solar site completely without shade from trees, chimneys, surrounding buildings, etc.? It is important to do a shade analysis of any potential solar site since it can be surprising what ends up being shaded at different times of the year. Although you can get a good idea by a cursory site examination, it is important to be forward thinking and plan ahead. What if those trees that are currently 20 feet tall are at 40 feet in 15 years?

There are two specially made tools which solar professionals use for shade analysis in site assessments. The Solmetric SunEye and Solar Pathfinder are both widely accepted as industry standard professional shade analysis tools. By using one of these devices, a solar professional will be able to position your system so that shade will not be an issue and there won’t be any surprise shadows at different parts of the year.

Solmetric SunEye

Solmetric_SunEye.gif

Solar Pathfinder

Solar_Pathfinder.jpg

Part of the reason it is so important to do shade analysis is that any shading of a solar module or array can disproportionately affect output. If you shade 25 percent of a solar array the output could go down as much as 75 percent. Although shading concerns can always be mitigated by the use of microinverters, when you make an investment in a solar system you want to make sure it produces as much energy as possible throughout the year.

A Few Other Factors

  • Roof Age and Material
  • Electrical Service and Utility
  • Current Electricity Price
  • Available Incentives

Ideally you have a large south facing roof, pitched at your latitude in the northern hemisphere, and it is shade-free year round. If you’re home or property has passed the orientation, tilt, and shade tests you can begin looking at a few other factors to help decide on the right solar system.

How old is your roof and what type of a roof is it? Will you need to replace your roof in the near future or did you recently get a new roof? Installing a solar system at the same time as you replace your roof is a great idea so that they can have similar warranty lives. If you are going to need a new roof in the near future, you may want to wait to do the solar install at the same time, but if you recently got a new roof within the past 5 years this will probably not be a concern for you.

The solar installation on your home will be connected to your electric service panel and will back-feed your current electrical service. It is important that there is room on your panel board to place a 2-pole breaker for the solar system. In addition to the physical space your electrical service also needs to have the electrical capacity to take on the power produced from the solar system. A solar professional will be able to determine all of this for you and should also be able to fill out any paperwork required by your utility for interconnection.

The financial analysis of your solar investment is a very helpful tool that can assist you in your decision making process. When looking at the numbers you will take into consideration the price you currently pay for electricity, the price of the solar system, the expected production of the solar system, and any available incentives for a solar installation in your area. All of these factors are important but as long as you work with an experienced solar installer an ROI analysis should be provided for you.

Bill Ehrlich is a Mosaic blog contributor who works in the electrical industry. After graduating from Notre Dame with a degree in Finance he worked on a cattle ranch in Wyoming and then taught English in China. Returning home to the States he worked at Inovateus Solar, a solar integrator in South Bend, Indiana. Originally from Minnesota, he is currently getting his hands dirty doing electrical construction in the city of Chicago. Outside of work Bill enjoys investing, solar power, and most of all, investing in solar power!

This post originally appeared on Mosaic

Read more: , , , , ,

Photo credit: Thinkstock

have you shared this story yet?

some of the best people we know are doing it

80 comments

+ add your own
6:25AM PDT on Mar 23, 2014

solar power rocks! I rent, but wish I lived in a place w/solar power. ever since California's _fake_ energy crisis where our gas/electric companies powered down some electricity plants to inflate gas/electric prices, I absolute HATE my gas/electric company!!!!!

9:18PM PDT on Mar 21, 2014

I would love to go solar, but even if I could afford it, I live in a condo.

10:09AM PDT on Mar 21, 2014

I really want to add some solar but I really do not want to deal with the city zoning codes saying something about my outdated electrical service.

7:02PM PDT on Mar 19, 2014

Not yet - I still have my heart set on a cave with a stove pipe...

11:56AM PDT on Mar 19, 2014

Too expensive or I would do it in a heartbeat.

9:59AM PDT on Mar 19, 2014

Solar and wind power are the future of energy production Electric utilities will do anything to crush home solar because it cuts into their business Solar leases are in some states and offer no money down solar systems on your home that have cheaper rates than the electric utilities charge. The solar lease company repairs problems with the system.

7:52AM PDT on Mar 19, 2014

Still too expensive for me, although I would love to live on solar power.

5:37AM PDT on Mar 19, 2014

I am a huge fan of solar - proud to say that we have it covering our roof! Here in the U.K I am noticing more and more homes with it - now all we need is a bit more sun!!

5:02AM PDT on Mar 19, 2014

Thank you

10:14PM PDT on Mar 18, 2014

More solar. Need to make it more affordable.

add your comment



Disclaimer: The views expressed above are solely those of the author and may not reflect those of
Care2, Inc., its employees or advertisers.

ads keep care2 free

Recent Comments from Causes

These are not people who are doing this kind of work in that monstrous manner !!! They are frustrated…

The bible claims to be God breathed and inspired by God. Jesus said He was truth and the only way to…

meet our writers

Beth Buczynski Beth is a freelance writer and editor living in the Rocky Mountain West. So far, Beth has lived in... more
Story idea? Want to blog? Contact the editors!
ads keep care2 free

more from causes




Select names from your address book   |   Help
   

We hate spam. We do not sell or share the email addresses you provide.