solar energy
Big and Bigger
The opportunities and challenges of large-format solar modules by Aaron Hall, Daryl Hart, and Joe Thorpe
THE PAST FEW YEARS HAVE SEEN AN AMAZING
amount of solar module innovation. One of the biggest trends is literally about bigness—the emergence of the large-format, high-power module. With peak power ratings already well over 500 watts (and pushing toward 600 watts and beyond), these mega-modules are made possible by another photovoltaic technology trend: the transition beyond 72-cell modules featuring 156-/166-mm cells, to larger modules using cleverly manipulated 182- and 210-mm slices of silicon. Manufacturers have implemented cell-splitting, shingling and tiling, multi-busbar architectures, and dense cell-to-cell interconnect schemes (as well as bifacial technology) to drive up the power output in these supersized modules. Although the larger modules are just starting to be shipped at volume, market research firms predict they will dominate the utility-scale solar market within a few years. Large-format modules present both opportunities and challenges for developers, engineering, procurement and construction (EPC) companies, and operations and maintenance (O&M) providers. This article will examine some of the issues around the new big modules from the perspective of all three business sectors.
Anything New Means There’s a Learning Curve
The new, larger form factor and higher wattage of these modules will mean that everyone - designers, developers, owners, and financiers - will need to ensure all the implications have been considered. One key issue is compatibility; for example, optimizers may have voltage limitations. It will also be crucial to determine whether the larger modules are pushing amps in a way that requires upsizing wires, combiner boxes, and other balance of systems components. In addition, there’s the question of possible warranty implications; specifically, whether using large-format modules will have any impact on the warranties of other components in the project, such as mounting systems that may not have been wind-load tested or certified for the larger modules.
costs - to the tune of several cents per watt. Simply put, it means fewer modules to ship (and, in the case of 182-mm modules, more watts per shipping container), fewer modules to mount on fewer trackers or fixed-tilt racks (and more watts per tracker row), and fewer strings to connect to achieve the same installed capacity of the power plant. Plus, fewer systems to operate and maintain once the plant is up and running. The result? Decreased capital expenditures, lower levelized cost of electricity, and higher net present value, all of which has developers and asset owners excited. From a developer-owner’s perspective, there is additional risk any time a new technology is introduced, whether it’s in terms of financial bankability, higher insurance premiums, or simply the durability and performance of the module. While Tier 1 manufacturers have (mostly) good track records when it comes to quality and reliability, it’s early days in terms of real-world power generation numbers from the mega-modules, let alone degradation, failure rates, or other field performance data. Given the larger surface area of the modules, there could be concerns with cell microcracking or susceptibility to extreme weather events such as damaging winds, hail, or snow loads.
Site Design Advantages and Tradeoffs
More Power Means Lower Costs
The main advantage of these large-format modules is straightforward: the higher power output per module allows a reduction in the required balance of system (BOS) and electrical BOS components and, most importantly, lower installation
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MARCH• APRIL2021 /// www.nacleanenergy.com
Large-format modules offer a tantalizing opportunity for developers, giving their landowner partners and EPCs more flexibly to utilize and benefit from the project site acreage. A space-constrained site could include additional megawatts of capacity; for many markets and scenarios, this is a worthwhile tradeoff with a corresponding specific yield reduction. This flexibility could also provide transmission system injection benefits when using a solar-plus-energy storage system equipped with large-format modules. Site designers will need to factor in the increased module size in how they lay out the tracker rows, increasing the spacing between the mounting structures to keep the same ground-cover ratio (GCR),
