Page 20 - North American Clean Energy September October 2015

solar energy

Solving the Challenge of Building a Leak-Proof Array

Image 1
Hurricane simulation at Yanegiken Photo 2: courtesy of Border Solar A recent installation in Southern
Laboratory, Japan. Texas by Border Solar

Building a PV array to face the diverse environmental challenges of each site such
as wind, moisture, and hurricanes can be very challenging but is possible with

the use of simple design and quality materials.

Image 2
Securing each PV module with multiple fasteners can spread the mechanical load evenly Butyl lashing provides
throughout the roof surface and, more importantly, alleviates the torsion applied to a impermeability and elasticity. It is

rooing system due to thermal stresses; the thermal contraction and expansion of an array, easy to mold, yet highly resistant
which is primarily built with aluminum containing a high coeicient of thermal expansion, to punctures. It retains its elasticity and strength when exposed to service temperatures
has the most movement on top of a roof. One design, being that the rail is the module between -40°F and 248°F. Even with extreme luctuations in temperature, butyl tape allows
frame, mitigates such efects that a minimum distance between adjacent rows can be as low for expansion and contraction while preventing moisture from passing through. It has an

as 3mm (1/8”). 4” wide mid- and end- clamps distribute the clamping pressure on a larger efective life of 20+ years and is resistant to aging weather, mildew, acids, alkalis, and salts.
surface of the PV panel frame. (Image 1)
It is common knowledge that no matter how the attachment of a PV array is achieved,
he next step is the perfect sealing of each attachment point with butyl tape. Butyl was irst the ultimate sealing point is exactly at the penetration in the rooing paper, where a lag or
developed in the early 1930’s and today is the most important material for the inner linings fastener gets attached to the frame or roof sheathing. his is conventionally accomplished

of tube-less tires. Among its traditional applications are pool linings and lexible lashing for with the use of sealants. Typical sealants have an upper service temperature between 160°F
construction.
and 200°F. Butyl performs at temperatures up to 248°F, which makes it longer lasting due to
Butyl rubber’s unique combination of barrier properties, high damping, resistance to ozone, heat distress.
weatherprooing, and heat aging make it the ideal choice for many construction applications. Diligent product engineering and laboratory testing is imperative. Tests can include;

For instance, butyl rubber is commonly added to asphalt compositions in the manufacturing extreme conditions of constant UV light, temperatures up to 145.4°F, humidities at 50%,
of rooing materials to improve the weatherprooing and low-temperature properties of the and every two hours, a water spray inside the Carbon Arc machine. he specimens should be
asphalt.
monitored throughout the testing time and evaluated to discern quality and performance.

he code is simple and objective as far as
lashings for the PV supports. It states that
roof-mounted PV system lashings must
be installed in a manner that prevents

moisture from entering penetrations
through the roof plane (IBC & IRC 2012).
he current suggested guideline by the
WHEN IT CAME TO SECURELY ATTACHING National Rooing Contractor Association

5.38 MW OF SOLAR PANELS TO THEIR ROOF,
(NRCA) for the installation of lashings
for PV system stanchions on a steep-
TOYS“R”US DIDN’T PLAY AROUND.
slope, asphalt-shingle roof recommends
the metal lange be applied underneath

the rooing paper (under the upper
underlayment) for proper water shedding.
It is the only way to create a proper
water shedding lashing mechanism.

However, this can only be accomplished
simultaneous with the installation of a
new rooing system, and not on a retroit
of a PV system installed above an existing

roof; which is the majority of installations
in the US.
Even though the rooing paper is called
a secondary layer to protect the roof

American made S-5-PV kits and clamps are the industry standard in metal roof decking, it is more accurately described
mounting hardware. That’s why the biggest names in business rely on our as the irst layer, not only because it’s the
solar mounting solutions. They know that it’s only secure, if it’s S-5! secure.
irst one to be applied, but if the rooing
material or anything else fails, the rooing
Learn more at www.S-5.com or call 888-825-3432.
paper or felt is the layer that will protect
the roof decking from moisture intrusion.
With this in mind, the removal of nails to

20
SEPTEMBER/OCTOBER 2015
nacleanenergy.com