The desire for optimal energy production in large solar power plants has engineers looking to an invention created in the latter 1960s, a technology that has been dormant while the broader PV market has exploded. Bifacial solar cells and panels are possibly moving more seriously into play now thanks to cost drops and efficiency improvements.
A bifacial solar panel is essentially a solar panel that can collect energy from the front side and the rear side (a normal monofacial panel only collects energy from one side). Array Technologies, a leader in solar tracking technology, is now testing bifacial solar panels at its facility in New Mexico, evaluating the technology from several companies.
Single-axis solar trackers from Array Technologies have been delivering for three decades. It is a leader in solar tracker system design and engineering. Array Technologies is now comprehensively collecting and analyzing data from bifacial solar panels to quantify bifacial gain and compare it to the extra cost to the system in order to examine whether bifacial solar panels have a role to play in the future of the solar industry and especially in plants using solar trackers.
One of the undeniable takeaways from talking with Ron Corio, founder of Array Technologies, and his focused group of solar engineers is the extensive, comprehensive work they put into acquiring, analyzing, and quantifying bifacial gain. This is the kind of rigorous analysis that has apparently led to top-ranking reliability of the company’s products.
Bifacial technology demands special, idiosyncratic installation challenges — in how those panels are mounted, how the panels sit, and how they tilt. You have to consider ground albedo, irradiance, etc. Although bifacial technology was invented in the late 1960s, the company says that it only recently has reached prices that are commercially competitive. Kim Weaver, the lead engineer of bifacial products at Array Technologies, presents that, “Overall, bifacial panels now add only about three percent to the total cost of a tracker system.”
However, it’s not a simple cost–benefit calculation until the end. There is much to track and quantify to come up with both figures, engineers Andrew Murray and Kim Weaver note. Corio says, “that’s the thing about bifacial, it’s a big bucket of variables.”
At the beginning and the end of the day, it comes down to monitoring the power output, thorough evaluation of the surrounding climate and atmosphere, and fine-tuning the tracking algorithms for site-specific needs. There’s a big difference between flat and sunny deserts, rolling hills, shady locales, and variations in cloud conditions — so much to balance in the collection and accumulation of data. There’s also more work to put in to understand how the tracker affects bifacial solar energy collection, at a small and large scale.
Array Technologies is now working a DOE national laboratory to research and test the technology. Weaver shares that means that at their disposal is state-of-the-art equipment for monitoring, data acquisition, weather research, and simulation.
“The industry is driven by LCOE, the levelized cost of energy.”
Corio points to an emphasis that is what really matters at the end of the day for many a business — money. In the energy world, a key metric is the levelized cost of energy (LCOE). “Its the optimal LCOE point that we’re seeking, not the maximum power point. I mean people confuse that because you can get fancy and do dual-axis tracking but you couldn’t do it economically. [Another option is putting it] higher in the sky and trying to optimize that backside — there are a lot of tradeoffs. And you have to really understand all those nuances to deliver the best product. That’s our goal with what we are doing out there.”
Array Technologies is one of an expanding group that wants to implement standards for the industry. Charles W. Thurston also attended the press conference in New Mexico, for pv-magazine. Thurston points out, “Several of the tracker companies on this quest – including Array Technologies (ATI), NEXTracker, and Soltec – are just now building out test fields where a half a dozen or more different bifacial panels at each site will yield initial data sets ranging from four to six month periods. All these companies aim to accumulate several years’ worth of data, of which some elements are expected to be public information.”
After touring several test sites, a factory, and a field of solar panels in New Mexico, I was impressed with what Array Technologies is doing, but as Corio and the team repeatedly emphasized, it comes down to money. To better evaluate and educate this topic, it supported a 3rd party white paper on bankability of this tech, and repeatedly emphasized that they want to see standards developed in the industry to ensure quality, reliability, and bankability. The solar industry is still in its early stages, “Solar 101” as Corio says, with many more changes to come with the growth of knowledge and the industry’s bankability.
Thurston explains, “The field data will be compared with product performance software analysis models, including PVsyst, which predicts backside performance. The independent engineers will report the proximity between the predicted and actual performance in bankability studies for the tracker companies.”
“‘The first company to prove that a bifacial panel is the best performer on their tracker, even with only a 10% bifacial gain, will win big in the market,’ reckons Ron Corio, Founder and Chief Innovation Officer at Array Technologies. ATI suggests that the bifacial boost could range from 5 to 30% – one test with LG bifacial panels yielded a 9.5% gain.
“His company is using PVsyst to predict backside performance of its latest DuraTrack HZ v3 tracker model using bifacial panels from Canadian Solar, FirstSolar, Jolywood, LONGi, Hanwha Q Cells, and Trina Solar at a test site in Albuquerque that will start at 1 MW and grow to 2 MW.”
The first confirmations of the actual value of the bifacial/tracker combination are on the way this year. As Thurston points out, the data are expected to set an industry benchmark in solar technology advancement.
*Array Technologies covered the cost of travel and accommodation for this trip. However, there was no requirement to write anything. We are only covering topics we found interesting and potentially useful for readers.