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Roofing reality check. Top 3 considerations for solar.

06/11/15

  06:41:00 pm, by Laurel Hamilton   , 754 words  
Categories: All About Solar Power, Commercial Solar, Residential Solar

Roofing reality check. Top 3 considerations for solar

So, you are considering a solar power system for your home or business… and why not, given the myriad of social, environmental and economic benefits! But how do you know if your roof is a good candidate? This is one of the top questions to consider carefully before investing in solar. 

Many faces can make layout challenging.1. Do I have enough space?

The size of your solar system is dependent on your usage needs and the amount you want to offset. However, it is not uncommon to find homes and businesses which are “footprint-constrained” - meaning their system size is limited by the space available.

A few things to keep in mind as you look at your roof and ponder how big is big enough… First, while there are many different solar panels they are typically the same size. Run on Sun uses LG panels which are about 65 x 40 inches and can be placed in either a portrait or landscape layout. Panel energy ratings vary, 285-315 watt panels are currently available from LG. For an average home (5 kW) that means you would need around 16-18 panels to offset the bulk of your electricity.

Another limitation is that fire code requires three feet of clear space from all ridges. If you have an irregular shaped roof with many valleys and peaks it may make the layout very challenging. Given that the panels are rectangular and racking is mounted parallel to the roof, rectangular spaces are ideal. However, the 3-foot rule does not apply to uninhabited spaces such as garages and carports making them good options if your home lacks the perfect solar roof. 

Trees can shade your roof and degrade your solar panel output.


2. What if my roof is shaded?

Shading from trees, tall buildings, chimneys, or even parapets on flat roofs can significantly degrade the energy output from solar panels. Sometimes all that needs to be done is a generous trimming of that tree that’s gotten a little out of control over the years. Other times it means you really won’t get your money’s worth out of a solar system. But, if the shade elements are few and only during a short time each day, your roof may still be a viable candidate.

If this is the case be sure to talk to your solar contractor about inverters. We have written a great deal about the advantages of “microinverters” in handling shaded roofs, particularly those made by Enphase Energy.  “String inverters” on the other hand would be a bad choice as the entire system would degrade when any single panel is shaded. 

 

3. Should I re-roof my house before adding a solar system?

This may be the most important and frequently overlooked question to consider when researching if solar is right for you. Part of what makes solar a great investment is the 25+ year lifetime of the system. But if you have to re-roof during that time there are added costs to remove and re-install the system. If you are planning to re-roof during the lifetime of your solar array be sure you select components, such as the racking system, from companies that…A. will still be around 15-25 years later, and B. will be able to provide compatible replacement parts when pieces are lost during removal and re-installation. Avoid newer companies testing out “state-of-the-art” racking systems and cheap companies banking on the solar boom alone.

For this reason we always ask owners the age of their roof. In southern California, a roof over ten years old should get a makeover before installing solar. If you are unsure of the condition, it is a good idea to have a professional roofer take a look and give you an expert opinion. Sometimes solar contractors can offer this as part of their free assessment. (Run on Sun works with a very reliable roofer who is happy to take a look at any roof in question!) If the roof still has some life left in it but not enough to outlast the solar system you could re-roof only the area where the solar array will cover and plan to do the rest later. An added benefit is that the solar panels will actually protect your roof from the elements, helping it to last longer.

 

Unfortunately, you will likely be able to find someone willing to put solar on your roof even if it isn’t a good candidate. But if they aren’t discussing the above issues with you, then red flags should be flying! To ensure you get the best investment possible, do your research, take a good long look at your roof, and discuss all of your concerns with your solar contractor. 

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2 comments

Comment from: jeff spies  
jeff spies
Bravo Jim! I hope more solar installers start following this ethic of advocating re-roofing before solar is installed. The long term cost benefit of starting with a new roof under the array are almost always a great ROI.
06/14/15 @ 11:46
Comment from: Jim Jenal - Founder & CEO
Thanks, Jeff - but credit for this piece goes to our awesome Projects Coordinator, Laurel Hamilton. You’ll get to meet her at InterSolar next month! (And we will both be needing Battle of the Bands tickets - hint, hint!)
06/14/15 @ 12:50


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Jim Jenal is the Founder & CEO of Run on Sun, Pasadena's premier installer and integrator of top-of-the-line solar power installations.
Run on Sun also offers solar consulting services, working with consumers, utilities, and municipalities to help them make solar power affordable and reliable.

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