Building codes exist to make people safe. The codes also impose costs on manufacturers required to meet those codes. In the low-slope rooftop photovoltaic systems market – which is the centerpiece of the growing commercial and industrial (C&I) solar segment – certain codes may provide a barrier to entry if they are interpreted strictly enough.
The International Building Code, a consensus document published triennially by the International Code Council, contains the model code language that is adopted by the vast majority of building departments across the U.S. Although the code has near-universal application in certain areas, such as live and static loads, its more exotic provisions for regions with significant seismic activity or extraordinary wind loads are subject to variable local interpretation by authorities having jurisdiction.
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Developers and engineering, procurement and construction companies serving the C&I space in markets with high seismic areas can select vendors with appropriate certification and keep experts with specialized engineering and permitting experience on staff or on call. However, the vendors themselves have to produce products that pass muster in the first place.
According to Andrew Barron Worden, CEO and founder of New York-based GameChange Racking, designing and engineering products that meet the strict standards of particular markets can be a challenge because the need to maintain multiple product lines for specific markets places a tremendous burden on the company. This burden is in the form of additional product development and personnel, specialized components, and inventory control resources. In an industry in which cost-per-watt is one of the main determinations of market success, specialized product lines can be prohibitive.
‘In terms of seismic codes, Los Angeles [L.A.] County is a leader in strictness, for lack of a better word,’ Worden says. ‘There are two approaches to the code, but practically speaking, there is only one.’
One of the approaches to satisfying the L.A. County seismic requirements for low-slope rooftop PV systems is to construct the racking and mounting system so that the whole array will slide if it has integrity as a system – like a plate on a table. But, even though there is code there that provides for that, Worden says, none of the authorities will let you do it because it's new and scary.
‘The inspector is not going to get a raise if he takes a risk and the thing blows up, right?’ Worden says. ‘From their perspective, why take the risk when you can attach the mounting like crazy everywhere? This is a perspective I understand. In many ways, this is the right thing to do.’
It may be right from a code-based perspective, but it is a complicating factor for a manufacturer of mounting systems. Most ballasted roof systems – and the prevalent systems out there for the rooftop C&I market – essentially are arranged with spaced ballast pans with wind deflectors between them. The panels set atop this system transfer the load in a seismic event, which is the fundamental problem.
The traditional code interpretation is to counter the seismic forces with a combination of friction and penetration to handle the lateral seismic load on the system. This is the only solution that most inspectors will accept, Worden says. It requires incorporating a lot of attachments between the mounting system and the roof.
‘Like, a lot of attachments,’ he emphasizes. ‘One for every couple of panels. It can be done. Some companies do that successfully. It's just that the number of attachments is very high.’
For reasons of product specialization, additional labor and rooftop penetration, Worden says he did not view this as the appropriate solution. Just over a year ago, GameChange developed its Grid-Lite system specifically to address seismic requirements, but in a way that might ultimately prove to be broadly applicable, even in markets where seismic requirements are not applicable.
The company's approach was to develop a structure that locked up the PV panels on a grid that is attached by rails, like a piece of graph paper. The panels are dropped in the spaces between the rails. Because load can transfer through the grid, Worden says, you only have to attach the whole structure at a few points. When the seismic event hits, the whole grid is either moving together or it's all stuck to the roof.
‘You don't need much ballast because the mounting structure is a single assembly,’ he says. ‘This has a double function in that when the wind tries to pick it up, instead of just picking up one section, it has to lift the entire array.’
Another consideration was to make the structure out of steel rather than aluminum because the latter can become ‘wiggly’ under seismic loads.
Although the Grid-Lite design satisfies strict seismic codes, it does compromise the law of solar manufacturing that says a company should have as few product lines as possible to keep costs down. Worden says that the new product has broad enough application.
‘You can use the same product in a non-seismic area – you just wouldn't need attachments,’ he says. ‘In many cases, you don't even need ballast. On roofs where there is no wind loading, the panels themselves provide enough weight for the system.’
Worden says he expects GameChange to be selling enough of the Grid-Lite system that it should start to displace the company's other rooftop C&I products.
