By David McDougall, senior business development manager, photovoltaic group, H.B. Fuller
Although adhesives and sealants are small pieces of the solar module installation process, they play a big part in the quality, reliability and lifespans of modules. Despite this, their roles in crafting and installing modules is often not fully understood. To make the most of installations, it’s critical for installers to understand how these materials can help complete successful projects that withstand extreme temperatures and conditions for decades.
Let’s dive into what into what installers need to know about PV/solar adhesives and sealants before starting their next project.
Waterproofing the roof
The primary purpose of sealants is to waterproof the roof, which is crucial for ensuring a clean install and a long-lasting bond. To produce a solid hold, create a dam with a bondline thick enough (at least 2 to 3 mm) to hold off water. Be careful not to make the bond too thick, otherwise it’s susceptible to cohesion failures.
The sealant’s temperature is also a factor in the installation process. It’s important to apply it to the flashing as close to room temperature as possible, since low temperature can attract condensation while high temperature can flash off some of the cure chemistry.
While these principals—creating a dam and accounting for temperature—are not always practical due to the unpredictable nature of installations, they should be adhered to as often as possible to achieve reliable holds.
It may seem obvious, but understanding the different materials to be bonded, or substrates, along with the roof and solar mounting systems, goes a long way in terms of identifying which adhesive is right for your project. Some of the most common solutions include:
MS polymers: Used in roof materials like asphalt and are better suited for projects with low surface area.
Silicones: Ideal for projects with metal-to-metal systems.
Butyl solutions: Versatile solvent that’s compatible with a wide range of resins. Used in architectural, household and industrial markets.
Extreme temperatures and conditions
No matter where solar modules are placed throughout the country, they will be exposed to harsh conditions—both weather- and system-related. That’s why understanding various weather and project conditions plays a key role in successful installations. There are numerous settings to account for, but a few conditions to keep top of mind are:
Ambient conditions: These can impact the cure. Heat plays a role, but humidity is the primary condition that affects the speed of the cure (see the graph to the right).
Cleanliness: Greater cleanliness results in better adhesion. After all, roofs can be messy, so do what you can to have a clean, dry surface.
Carrying load: Although bolts and hardware will be the primary load carrying component, adhesives and sealants play a role here. They can also contribute to dampening loads of wind to the hardware.
Speeding up the process to lower costs
Installation is a costly procedure. The Office of Energy Efficiency and Renewable Energy’s On the Path to SunShot series, part of the organization’s SunShot Initiative, found installed systems prices in 2015 were highest for residential ($3.10/W), then commercial ($2.20/W), then utility ($1.80/W). The installation process can be responsible for up to 30 percent of those prices; labor alone is responsible for roughly half of installation’s expenses. These high expenses make streamlining installation one of the industry’s big priorities.
One way to lower installation costs is by having materials suppliers, such as H.B. Fuller, customize a package or installation process that integrates with an installer’s procedure. With this method, the sealing process is incorporated into the overall process, speeding up installation and reducing labor hours, which in turn lowers installation costs.
Adhesives and sealants: Holding it all together
A greater grasp on applying adhesives, identifying the best substrates for projects, and accounting for extreme weather and conditions are all crucial pieces of a successful installation. Installers who make a point of thoroughly understanding how adhesives impact installations will better positions themselves to install modules that are reliable, efficient and long-lasting.
To learn more about PV/Solar adhesives, visit www.hbfuller.com/solar.
David McDougall is the senior business development manager for H.B. Fuller’s photovoltaic group. The company has been a leading provider of adhesives, sealants, and specialty chemicals for over a century and serves customers in engineering, electronic and assembly materials, hygiene, construction, automotive, packaging and other consumer businesses. With the purchase of TONSAN Adhesive Inc. in 2014, the company has become a major player in the market for solar products worldwide.