Issues With PV Cables on Residential Rooftops

Cable management is difficult with rooftop PV installations because the array is coplanar to the roof and it is difficult to see and access the cables once each module is in installed. There are two major issues that occur with these types of installations.

  1. Unprotected PV cables can be damaged by squirrels or other animals that will nest under the array and claw or chew the cables and connectors.
  2. Obstructions under or around the edge of the PV array can hinder drainage and cause leaks into the roof.

To address issue #1, good wire management is one of the best available defenses against squirrels and other nesting creatures. The NEC states that USE-2 (PV wire/cable) must be secured within 24” of a junction box and then every 24” of length. While this is adequate for other installations, roof mounted arrays need better support and protection for the cables. Every 12” to 18” is minimal to prevent drupes in the cable.

The picture below is of a ground mounted array where wire management is easy to achieve. It is exceedingly difficult to achieve this with a coplanar roof mounted PV array. Even with this level of wire management, a squirrel can still chew on the cables; they are still unprotected.

Underneath view

Wire management methods vary depending on the racking manufacturer but none of them fully protect the PV cables from squirrel chewing damage. Here are a few methods.

SnapNRack
SnapNrack uses their open rail system for wire management. The plastic clips secure the cables into the rail trough.

 

Generic cable clips that attach to the module frame.

Generic 1Generic 2

 

Cable ties (zip ties) These are convenient to use but they must be rated for the lifetime of the array.

Cable tiesCable ties

The problem with zip ties is with their strength and usage rating. The typical black zip tie may not have a sufficient rating for the lifetime of the PV module.

Extreme UV

Another code requirement is the minimum bending radius of USE-2 and listed PV wire. USE-2 has a minimum radius of 5x the diameter of the cable; that is about the curve of a large cup. PV wire usually requires a minimum radius of 8x the diameter of the wire; that is about the curve radius of a good hamburger.

Another method of protecting the PV array cables from damage is to screen the exterior of the array to prevent entry. There are several products on the market but I have heard stories where squirrels still found a way inside the PV array.

Array screen 1Array screen 2

To address issue #2, obstructions under or around the PV array can cause water to enter the roof. The screening could cause a problem if leaf debris reaches the top of the PV array. If leaf debris is not an issue, the screen may be a good solution.

Any time there is a possibility of leaf debris reaching the upper portion of the PV array, it is imperative that there are no obstructing debris from being washed asway. If leaf debris is present, it may be best to keep the array high above the roof and use the best wire management techniques without screens.

nest under PV array
Nest under a PV module
IMG_7291
Wires chewed by a squirrel

 

 

 

 

 

 

 

 

If there is not a possibility of leaf debris reaching the PV array, screening is the best method to prevent nesting creatures from getting inside the array and damaging the cables and connectors.

Kelly Provence
IREC Certified Master PV Trainer
Solairgen School of Solar Technology
800-262-7560
www.solairgen.com

Styrofoam packing

Shouldn’t Packaging of Renewable Components be Renewable Too?

As far as pure energy goes, it doesn’t get better than solar energy. Photovoltaic (PV) energy technologies are improving and growing at an impressive rate. This industry hopes to be a major source of electrical energy on Earth in the not-too-distant future. At the rate it is growing, that will probably happen within 10 to 20 years. That sounds great but there is a dark side to the PV industry’s growth and it is in the way materials are facilitated to the complete installation of a PV system.

Before I talk about this environmental dark side of the solar PV industry it is worth noting its bright clean side. If all the energy required to manufacture and facilitate the installation of the PV system was derived from fossil fuels, it would take only two years of operation to offset that non-renewable fossil-fuel energy. As renewable energies become more dominant that figure will become shorter. Ultimately the process of offsetting the non-renewable, fossil-fuel energy required to manufacture and implement a PV system could be close to zero. Unfortunately, there is still an environmental dark side that has not been offset. This has to do with the negative effects of the front end and back end of product manufacturing, mining and packaging.

On the front end, mining is necessary to get the raw materials to manufacture PV cells, PV modules, inverters, batteries, support structures and electrical conductors. It is possible to reduce the effects of mining by using materials that are more plentiful in the Earth’s crust but there will always be a requirement for mining. It is also possible to recycle materials that are currently reaching the end of their useful life. The obstacle here is usually financial since it is often lower cost to mine for new raw materials than to recycle them from previously manufactured products containing these same raw materials. Interestingly, even if it takes less energy to recycle a material, it may be more difficult and more expensive to completely facilitate the recycling process. When recycling is disadvantaged by these economics, tax incentives or subsidies should be put in place to make recycling more lucrative. The back end of manufacturing is packaging.

Almost every manufactured product is packaged before being sent into the marketplace.

PV modules are packaged on wooded pallets with plastic separators. They are often wrapped in stretch plastic or they are packaged in pairs with cardboard. Plastic is a forever-material that is almost completely non-recyclable. Wood and cardboard-based packaging is much more recyclable. Its recycling should be encouraged though tax incentives or subsidies.

  • Inverters are packaged in cardboard and protected internally with either Styrofoam, polystyrene or corrugated fiberboard. Styrofoam and polystyrene are forever-materials that are non-recyclable and should not be used. Paper based products like cardboard should be used instead.
  • Batteries are typically packaged the same way as inverters but primarily with cardboard.
  • Small balance-of-system components (BOS) are shipped in cardboard, plastic and they use bubble wrap and foam peanuts to secure the items during shipment.

Inverter packaging

Packaging PV products with forever-products that are non-renewable and non-biodegradable is completely unacceptable. The purchaser of these products has a lot of influence over how these products a packaged; the best action is an email or phone call to the sales associate for the manufacturer as well as to the distributor of the products. Solar PV is a renewable product industry, we need to remove non-renewable, non-biodegradable products from the packaging process.

Kelly Provence
Solairgen, Inc.
IREC and NABCEP Certified PV Trainer
www.solairgen.com
706-867-0678
800-262-7560

ManInstalling6A

Choosing a Solar Installer 101

The U.S. is growing in residential and commercial solar PV installations – and fast. If you’re a home or business owner, owning and paying for a solar PV system is easier than ever, but there are guidelines for potential solar PV owners to make the process successful – starting with who you choose to install your PV system. When you enter solar installer search criteria into your search engine you’ll get a long list to choose from. So how can a home or business owner tell who is, or isn’t, a competent professional installation company?

First, at least one person with the contracting company must be a licensed general contractor or licensed electrical contractor to legally write a contract for the PV installation. Also, it’s a good bet that if an installation company has been in business for a few years, they’ll have at least one NABCEP Certified Installation Professional on their team. A NABCEP Certified Installation Professional has been through many hours of advanced solar training, has experience installing and designing PV systems, and has passed a demanding nationally recognized exam. Ask questions. Reputable solar installation companies won’t mind answering them.

The solar training an installer gets can mean the difference between a qualified, competent installation professional and an installer who is less qualified, or just out for the money. Ask the company representative where they received their solar installation or solar sales training.

A solar training program that is IREC Accredited, or a trainer who is IREC Certified as a Master Trainer has achieved the highest level of quality and excellence in the solar industry today.  If the team you’re interested in isn’t NABCEP certified, it’s a good idea to make sure they were trained in an IREC Accredited program, or by an IREC Certified Master Trainer.

Of course, there is also word-of-mouth. Join Facebook solar groups where you can ask other PV system owners about their experiences. Solar is a long-term investment in your home, your business, your future and your family.  Doing your homework before contracting with a solar PV installation company could mean the difference between an installation that is reliable or one that requires expensive troubleshooting.

Leigh Hamilton
Solairgen School of Solar Technology

Solairgen Announces PV-221 Advanced Design and Analysis Training


Solairgen, a leading national solar PV installation training organization is pleased to announce its new solar training class, PV-221 Online Advanced Design and Analysis.

Dahlonega, Georgia (Vocus/PRWEB)February 04, 2011 — Solairgen’s Online PV-221 Advanced installer training class covers PV system performance analysis, in-depth troubleshooting, and system integration. It provides the student with a thorough understanding of advanced PV system technology, giving the PV designer an understanding of all parameters affecting a system’s performance. The class provides its students with the ability to design larger arrays, or commercial systems, with competence.

Mr. Kelly Provence, Solairgen’s CEO, said, “We are excited about offering PV-221 online. Our goal is not just to bring skilled career individuals into the solar market through our introductory training class, PV201 Online Design and Installation. We saw a gap in training, between introductory classes and those individuals who want to include solar installations in their long-term career path. We bridge that gap by providing students with superior skills as PV system designers. Our students get in the industry, stay in the industry, and achieve a greater degree of expertise for larger, more complex commercial system design and installation.”

About Solairgen:
Solairgen provides photovoltaic (PV) panel installation training classes for the solar energy industry through a complete program of NABCEP approved installation training courses, beginning with its IREC/ISPQ Accredited PV-201 Online Design and Installation training. Next, Solairgen’s PV-203 is an advanced, forty hour solar training class covering advanced topics of solar installation.  Additional classes offered by Solairgen are PV-311, NABCEP Exam Prep – an intensive study class to help students pass the NABCEP Certification Exams. Solairgen is also an approved provider of the NABCEP Entry Level Achievement Exam, and provides NABCEP approved classes that meet NABCEP’s training requirements for the PV Technical Sales Exam and the Certified PV Installer Exam.

Taking Solairgen’s full program, PV-203 System Design and Installation, PV-221 Advanced Design and Analysis and PV-311 NABCEP Exam Prep prepares students to pass the NABCEP Certified PV Installer or PV Technical Sales Certification exams – and to excel in the solar industry.

Please check Solairgen’s website for training class dates and times by following the link: Solar Training Classes

Five Things You Should Look For In A Solar Training Course

As time goes on, more and more people are starting to look for alternative means of power for their homes. Some consumers are simply tired of the rising costs of energy, some are driven by a desire to reduce our carbon footprint on the planet – almost all are motivated by both reasons.

Solar panel installation is growing in popularity as a career and the job market for technicians with solar training certification is growing along with it. So, the proper training, from introductory classes to advanced education and career preparation is critical for a successful career. Does anyone really want an installer without the best training and expertise to tie new technology into their home’s power grid without specialized training?

Since now is a great time to get into the Solar Energy market, here are the minimum criteria to look for from a training provider to get the best possible training in the industry:

1. Research the training provider and their classes. All Solar Training courses should be fully accredited by IREC/ISPQ.

2. The class you choose should provide students with hands-on training at an IREC accredited training facility.

3. The instructors should have many years of experience in Solar Panel Installation, and be NABCEP Certified Installers themselves.

4. The training company should have a good reputation. If possible, get references from those who took their classes and have “made it” in the solar energy industry.

5. The company should have a long history of training technicians and installers, and be well known within the solar training industry.

If they meet all five tests, then you will have found a Solar Training provider that you can trust.

You should check your state’s laws for contractors’ requirements. Some states have specific laws or certification requirements for solar power installers to meet. Most states require the participation of a fully licensed electrician during the installation process.