Solar Roof Systems: The Good, The Bad, and The Ugly

Course Description

Installing a solar roof system on your building should be a decision that rewards you with energy savings as well as piece of mind knowing you are doing your part to help the environment. What many building owners may not realize is that installing a solar roof system could damage their roof, void their roof warranty and end up costing them more in the long run.

  “Solar Roof Systems- The Good, The Bad and The Ugly” will identify the potential issues with a rooftop solar installation, what questions they should be asking and how to avoid serious, costly problems.

Please note that AIA and RCI credit can not be earned for watching the recording. Please provide your email to get updated on any upcoming building construction webinars.

 

Note: The slides may appear to not be moving at first due to a technical difficulty. However, they resume throughout the video.

Learning Objectives

-What are some common problems that may be encountered with solar roof installations

-What information should you know about your building/roof to determine if your facility is suitable for rooftop photovoltaics

-Important questions you need to ask the solar installer before you decide on a system

-Does my roof warranty cover a solar roof installation and if not, what can I do

-New developments in the industry that can eliminate most if not all of the concerns around a solar roof installation.

Sika Roofing, a Division of Sika Corporation, is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) cannot be earned for the above webinar as the live event has concluded. However, we are happy to schedule a Lunch and Learn for your team!  

About the industry expert:

Joe Schwetz Headshot

Stanley P. Graveline

Stan is the Senior Vice President, Technical Services, Sika Corporation – Roofing, Canton, MA. He has worked in the roofing industry for more than 35 years in various technical, sales and management capacities in Canada, Switzerland and the USA. He has participated in technical committees and standards writing bodies in North America and Europe. 

He has written numerous articles and papers and is a speaker at various national and international symposiums and other industry events on roofing and sustainability topics. He has a Bachelor of Applied Science (Chemical Engineering) degree from the University of Ottawa and a Masters of Business Administration from the International Institute for Management Development, Lausanne, Switzerland.

Questions and Answers

1. How do you determine if there is any moisture infiltration in the roofing system prior to installation of the solar systems?

An infra-red scan of the entire roof surface, supplemented with confirmatory cut tests will allow you to determine if there is moisture in the roof and if so, where.

2. What time frame do solar panels last?

PV panels are typically projected to last 20 years or more.

3. Is there a preferred cover board material and minimum thickness?

Both gypsum based and high compressive strength polyisocyanurate cover boards can be used. The gypsum based products have higher compressive strengths and enhance fire resistance, compared with the polyisocyanurate based products. The thicker the board, the greater the protection, but there is no minimum thickness requirement.

4. If you were integrating a PV system into a 45 degree pitched asphalt shingle roof system, what would be the best way to connect the PV racks? Would you possibly consider a standing seam roof beneath the PV system, and the remainder of the roof being asphalt?

We recommend you contact suppliers of such materials for their input.

5. What roofing companies use this combined warranty for the PV and the roof?

The membrane system supplier’s authorized applicators can install the referenced system for coverage under the combined warranty.

6. How does the securement of the field membrane affect the securement of the PV system with a roof and membrane integrated system? What if the membrane separated from its substrate?

The performance of the membrane integrated PV system is dependent on a properly designed and installed roof assembly. 

7. Does the roof system have to be fully adhered to use these integrated systems?

The system can be installed on membrane systems secured with any of the common techniques: adhered, mechanically attached and induction welded.

8. Are Factory Mutual approvals available for the membrane integrated systems?

Not at this time.

9. How about installing on clay, metal, galvanized, roofs?

The membrane integrated approach presented can only be installed on low slope thermoplastic vinyl membranes.

10. Does guarantee include a minimum power output?

Power output guarantees are provided by the photovoltaic panel supplier.

11. What PVC roofing manufacturers provide this warranty and how many solar companies take part in this type of warranty?

In accordance with AIA’s policies for CEU courses, we cannot discuss specific manufacturers as part of the program. Please contact us directly to discuss system specifics.

12. In the membrane-integrated system shown, is adhered or mechanical connection recommended for main roofing?

The system can be installed on membrane systems secured with any of the common techniques: adhered, mechanically attached and induction welded.

13. How much does the typical system weight (PV solar and support attachment to roof)?

The distributed load is typically less than 4 lbs / ft2 in the field of the roof.

14. Does SIKA have a hybrid system with membrane? If so, how does the designer-contractor-SIKA address the scope and design responsibilities?

In accordance with AIA’s policies for CEU courses, we cannot discuss Sika specific products and systems as part of the program. Please contact us directly to discuss options we have.

15. How do you determine if there is any moisture infiltration in the roofing system prior to installation of the solar systems?

An infra-red scan of the entire roof surface, supplemented with confirmatory cut tests will allow you to determine if there is moisture in the roof and if so, where.

16. On new construction, are there advantages in using metal roofing panels with integrated PV?

The ideal solution for a given project depends on the roof construction for the specific facility based on a number of variables such as roof slope, the roof system’s load capacity, design wind forces, etc.

17. Typically there is other equipment on the roof. Does the integrated mounting system address these elements?

The integrated system is extremely flexible with regards to lay-out and accommodating roof mounted equipment and penetrations.

18. What current standards and approval processes govern the proprietary attachment assemblies? How do you see the codes evolving to address this industry?

There are no specific standards that govern proprietary roof attachments used in solar. The most common process is to submit stamped structural analyses specific for every installation project based on generic codes and standards.

19. Are the integrated mounting systems provided by the roof membrane manufacturer? How many manufacturers are there for this product?

All the components of the integrated solution shown in the presentation including the roof system and the non-penetrating PV attachment assembly are provided by the same roofing manufacturer.

20. Is there a preferred cover board material and minimum thickness?

Both gypsum based and high compressive strength polyisocyanurate cover boards can be used.  The gypsum based products have higher compressive strengths and enhance fire resistance, compared with the polyisocyanurate based products. The thicker the board, the greater the protection, but there is no minimum thickness requirement.

21. Would you install solar panels on a standing seam copper roof approximately 30+ years?

We recommend you contact a supplier of such a system for their input.

22. On roof over the five years would you recommend stripping the field seam?

The seams of a properly installed thermoplastic roofing membrane will last as long as the sheet and should never require stripping. As noted in the presentation, we discourage installing solar PV on roofs older than 5 years.

23. How long have click attachments been used in the field?

The first installation was completed in 2012.

24. Does the roof system have to be fully adhered to use these integrated systems?

The system can be installed on membrane systems secured with any of the common techniques: adhered, mechanically attached and induction welded.

25. Is there a standard cost per KW?

Costs are dependent on a number of project specific parameters.

26. Is there any minimum roof area and clearance requirement for the roof top solar panel installation?

There is no minimum roof area required for the installation of rooftop solar. Jurisdictions can develop their own clearance requirements, but many follow California Fire Code, which requires the following: 

• 6 ft perimeter setbacks for large commercial buildings, 4 ft for small buildings

• 8 ft aisles every 150 ft

• 4 ft setbacks around most roof obstructions, with 4 ft wide access to roof hatches.

27. Is there a minimum size for a commercial roof to generate a respectable amount of electricity?

The economic benefit relative to solar PV array size varies widely by climate, local electricity costs, to name but two of the most important drivers.

28. How well does this work with a torch down roof?

The system is not intended for use on a torch down roof.

29. Are you aware of solar ready requirements in the 2015 IECC code by some states, including MA?

Yes, we are aware of the solar ready provisions that has been adopted (with some changes) by MA and other states. The big items are the requirement for an obstacle-free solar zone (50% of roof area) and a designated interconnection pathway.

30. Does Sika require walk pads to be installed between solar arrays in order to qualify for the membrane integrated warranty?

Walk pads are not required between arrays.

31. How does the integrated membrane system address potential damage to the underlying roof membrane caused by thermal movement of the array rails?

The system is designed to allow for thermal movement of the rails without imposing any stress on the membrane assembly.

32. Are membrane integrated systems installed post roof membrane installation?

Yes, the roof installation should be completed before beginning the installation of the solar PV system.

33. Do the solar panels raise the roof surface temperature?

A solar panel that is mounted directly against a roof surface, with the frame touching the roof and no possible air flow, can raise the temperature at the roof surface. But if there is a gap of at least 2 inches between the panel and the roof surface, which is common with a fixed tilt commercial low slope roof system, that effect is negligible. In fact, these systems will shade the underlying roof on sunny days, keeping the temperature lower than the surrounding roof.

34. How do we coordinate the installation of the panels - do we use your rails?

Typically, the entire assembly up to and including the rails is installed by the membrane system manufacturer’s authorized applicator.

35. How many/SF of the integrated systems has Sika been involved in?

The system has been installed on more than 10 million square feet of roofing.

36. Do the Sika tech inspectors inspect for the PV install in conjunction with Roof during construction?

The roofing membrane system manufacturer’s technical personnel inspect both the roofing assembly and the integrated assembly up to and including the rail.

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