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Bifacial Solar is Ready for Primetime

There is no doubt that bifacial modules are ready for their breakout role in the world of solar photovoltaic projects.

By the dawn of 2020, there will be a cumulative 5.4 gigawatts of bifacial solar capacity installed globally, mostly in Asia, according to Wood Mackenzie Power & Renewables’ first report focused on the global bifacial market. In five years, there will be a nearly equal share of deployment between Asia and North America, with the cumulative installed capacity growing 10-fold, according to WoodMac.

Bifacial modules, as the name suggest, harvest energy from the module’s rear side, in addition to the front side. The energy gain is largely dependent on the light reflection, known as albedo, off of the ground surface.

The steep rise of bifacial has been enabled by better system economics, higher energy yield, and more robust modeling and field data, providing assurance to developers, operators and financiers that are looking to see higher gains at increasingly lower costs out of solar projects.

More power, from every angle
The emergence of bifacial comes as large-scale solar developers compete on prices, which continue to push down across the globe. While bifacial is a leading trend that is offering higher power production, the front side of modules continue to see higher gains too.
Bifacial PERC (passivated emitter rear contact ) solar modules have inherited all benefits of one-sided mono PERC technology with higher power output and better reliability. The rise of mono PERC cells across the industry is a major factor in the falling costs for bifacial modules, which are primarily made with mono PERC cells. PERC technology increases cell conversion efficiency by adding a dielectric passivation layer at the rear side of the cell that reduces surface recombination.
Manufacturers can cost-effectively increase efficiency beyond standard multi c-Si, building higher-wattage modules, and generating more power per square foot in a solar installation. Mono PERC cell capacity will account for half of the total global cell capacity in early 2020s, according to WoodMac.
While bifacial systems may incur slightly higher cost versus their monofacial counterparts, the significantly higher energy yield expected from bifacial can more than offset its impact and offer better levelized cost of energy comparing to a monofacial system. WoodMac also expects bifacial production costs to fall by another 23 percent in five years.
Bankability rising
To establish bankability of bifacial energy yield, module manufacturers have worked closely with third-party labs and customers to collect field performance data on bifacial PERC modules and validate backside energy yield.
Field data from LONGi and the Renewable Energy Test Center, for example, has found that LONGi bifacial PERC modules offer an average range of 8 to 20 percent in back power generation gains depending on ground-surface environments. In one field test, for example, asphalt yielded a nearly 11 percent gain with bifacial while a white ground cover offered 15 percent gains.

Bankability comes with time, as most investors want at least a year of data. But there are other important steps towards building the data set that allows for bankability. In early 2019, the International Electrotechnical Commission released IEC TS 60904-1-2:2019, which will serve as the common basis for measuring the current-voltage characteristics of bifacial products.
Simulation of bifacial modules has also improved significantly. “The experts in the industry think there’s a pretty good correlation between simulations and the field performance now,” said Hongbin Fang, director of product and technology for LONGi. “We have seen more and more investors getting comfortable on bifacial technology and willing to finance the backside energy yield from bifacial PERC projects.” Since introducing its first-generation bifacial module HiMO2 to market in 2017, LONGi has deployed more than 2.4 gigawatts of bifacial PERC modules globally.
Early this year, LONGi introduced Hi-MO4, its next generation half-cut bifacial PERC module made with M6 (166mm) wafers. Hi-MO4 bifacial PERC module offers front side power up to 440 watts, a 15 percent increase over the previous generation power generation capacity, and an estimated $0.03 per watt balance-of-systems cost savings compared to a solar project with polycrystalline modules.
It is not just module performance data that has to be proven in coming years. Developers and financiers also need to better understand the seasonality of ground cover albedo as well as the optimal racking design and height for bifacial projects to maximize their return on investment. “It’s not just about the modules,” Fang said. “We need to look at it a system perspective to realize the full potential of bifacial technology.”
To learn more about how bifacial modules are boosting yield and lowering costs for solar projects, Join GTM and LONGi on November 21 for a free webinar, Lowering LCOE with Bifacial PERC Modules: a Case Study with LONGi’s HiMO4 at 440W. Register here to watch live or on demand.

Source: Greentech Media