With solar cell shingling, going to pieces is a good thing

Jocelyn Eide

Illustration showing how cell pieces are layered with solar shinglingAs market competition increases, businesses either innovate or get left behind. This is particularly true in the solar sector, where manufacturers work tirelessly on the next evolution in technology. One such breakthrough is solar cell shingling (or simply “shingling”). And it has a very attractive upside for your commercial solar investment: more efficient and reliable solar modules.

So what is shingling and how does it work? Like your friend’s relationship status, it’s complicated. And while investing time and energy to help determine whether five dates constitutes a relationship isn’t exactly rewarding, taking the time to understand shingling is worth a little brain stretch. That’s because it’s knowledge that can offer you bottom-line payback when you’re investing company capital in solar technology. 

Essentially, solar shingling involves cutting solar cells and arranging them in an overlapping pattern within a solar panel (or “module”). This has the effect of increasing panel efficiency—meaning it creates more power in the same amount of space. It also makes panels less susceptible to mechanical and environmental stresses, so the panels are more reliable too. That can translate to big wins, because higher efficiency and reliability mean more long-term savings on business electricity costs.

Getting more power from smaller pieces

At first glance, the entire concept of shingling seems a bit counterintuitive. Because photovoltaic (PV) output is related to surface area (the more, the better), cutting up a solar cell really shouldn’t result in increased efficiency, right? However, with the behind-the-scenes science, something called resistive loss is at work.

Like it sounds, resistive loss is power loss due to resistant properties of a conductive material. It happens in all conductors to varying degrees, but scientists discovered something unique about PV solar cells. Cutting down the size of the solar cell, or more specifically, cutting the solar cell into strips or pieces, mitigates resistive loss. This results in cell pieces that have less resistive loss and therefore greater efficiency than a comparable piece within a single uncut cell.

For solar shingling, a laser cuts solar cells into pieces“Cutting” a solar cell involves ultra-precise laser scribing done on the manufacturing line. The magic number of pieces into which a cell can be cut in order to decrease losses and increase efficiency is two or more. Theoretically, the cell could be cut into infinite parts, performing more efficiently with each division. But manufacturers reach real-world limitations (size, space and tools) much sooner, maxing out at approximately five or six cuts per solar cell.

It’s in the way that they layer it

Dividing or cutting a solar cell is one definitive part of shingling. The other is layering the cell pieces. It’s worth it to explain here that many panel manufacturers use solar cells from the same sources. This means each manufacturer starts with cells of the same size and relative efficiency. In other words, everyone is using the same general ingredients, so the real competitive advantage is the innovative processes manufacturers cook up to perform shingling—their “recipes” so to speak. These processes result in increased efficiency and durability, the leading considerations in choosing what solar panels to buy.

...everyone is using the same general ingredients, so the real competitive advantage is the innovative processes manufacturers cook up to perform shingling...

The catch (because nothing is quite that easy) with simply cutting the cells is reliability. So manufacturers solve this problem by overlapping the cell pieces within the panel. This overlapping results in a connection point similar to an expansion joint on a bridge—allowing a shingled solar panel to better withstand expansion and contraction from temperature changes, as well as any flexing due to wind. But you don’t want to go overboard with overlapping. The golden guideline is “minimal overlap means more power.” Less overlap results in a more active (power-producing) area that comes in contact with sunlight. There is simply more space available for power generation.

Fast facts on solar shinglingThe sticky side of solar shingling

Solar shingling does have a secret sauce: a specially-formulated electrically-conductive adhesive (ECA). This is used as a way to bind the solar cell pieces together and as a redundant conductor, further strengthening the module’s overall connectivity. Not all ECAs are created equal, and some ECA formulas have enabled great leaps in efficiency and reliability through direct cell-to-cell connection. With a stable direct cell-to-cell connection, the conductive metal ribbons soldered onto the front of the cells can be eliminated, thereby increasing the active area of the shingled cells and the module’s overall efficiency.

Replacing conductive metal ribbons with direct cell-to-cell connection also provides reliability benefits, because the front-side soldered metal ribbons have a tendency to break and peel under environmental (such as temperature and humidity) and mechanical (such as daily expansion and contraction) stresses. Damage to the metal ribbons results in compromised conductivity and lower power production—issues most solar customers would prefer to avoid.

Better technology for better alternatives

The solar market keeps getting better at delivering more efficient and reliable technology, and shingling is yet another step forward. For professionals researching commercial solar options for their businesses, shingled solar modules are worthy of consideration.The year-on-year savings from increased efficiency and reliability will shorten payback times.

During the solar consultation process, project estimates should cover anticipated business savings over the lifetime of the system, making it easier to calculate the break-even moment, as well as the estimated return on your commercial solar investment.

 

Related links:

How to go solar: getting to panel installation in 8 steps

Solar is trending as a top renewable investment worldwide

SunPower tops Fraunhofer’s first PV durability test report results

How solar power can increase your commercial property value

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