A bifacial solar panel is 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). Bifacial solar technology was created in the latter 1960s. It was dormant while the broader PV market exploded. It was too costly for incremental energy production improvements.

Bifacial solar panels
Bifacial solar panels on trackers. Credit: NPC

A CleanTechnica field trip and series of articles a couple of years ago mentioned, though, that bifacial solar cells and panels are moving more seriously into play thanks to cost drops and efficiency improvements. A recent scientific article published in the journal Joule confirms our earlier belief that this technology has promise.

Technology that tilts panels so that they can follow the sun boosts the electricity production of normal solar panels. This solar tracking is used in some solar projects, especially large ones in certain regions, but hasn’t been used in most. Bifacial solar PV technology, however, can get an especially useful boost from solar tracking technology, capturing much more sunlight than a normal solar array ever could.

The new report, “Global Techno-Economic Performance of Bifacial and Tracking Photovoltaic Systems,” confirms that tilting toward the light, for optimal sunlight collection from both sides, can be the most cost-effective solar option to date. The report determined that this combination of technologies produces almost 35% more energy, on average, than immobile single-panel photovoltaic systems. This reduces the cost of electricity by an average of 16%.

Image: courtesy of Joule

Science Daily reports:

“The results are stable, even when accounting for changes in the weather conditions and in the costs from the solar panels and the other components of the photovoltaic system, over a fairly wide range,” says first author Carlos Rodríguez-Gallegos, a research fellow at the Solar Energy Research Institute of Singapore, sponsored by the National University of Singapore. “This means that investing in bifacial and tracking systems should be a safe bet for the foreseeable future.”

The research article notes that most of the current PV installations use monofacial crystalline silicon PV modules with a fixed-tilt system setup. Things are going to change, though, as the more cost-competitive technology is apt to disrupt this dominance.

“The results reveal that bifacial-1T installations increase energy yield by 35% and reach the lowest Levelized Cost Of Energy (LCOE) for the majority of the world (93.1% of the land area). Although dual-axis trackers achieve the highest energy generation, their costs are still too high and are therefore not as cost-effective. Sensitivity analyses are also provided to show the general robustness of our findings.” Dual-axis trackers become more competitive as you get closer to the poles.

Dual-axis trackers become more competitive as you get closer to the poles.

Also, despite evidence that bifacial solar panels with single-axis tracking are more cost-efficient, Rodríguez-Gallegos doesn’t expect a rapid switch to this tech.

“The photovoltaics market is traditionally conservative,” he says. “More and more evidence points toward bifacial and tracking technology to be reliable, and we see more and more of it adopted in the field. Still, transitions take time, and time will have to show whether the advantages we see are attractive enough for installers to make the switch.

“As long as research continues to take place, the manufacturing costs of these materials are expected to keep on decreasing, and a point in time might be reached when they become economically competitive and you might see them on your roof,” says Rodríguez-Gallegos. “We then aim to be a step ahead of this potential future so that our research can be used as a guide for scientists, manufacturers, installers, and investors.”

Image: courtesy of Joule

Here’s a more detailed text summary from the report:

  • We find that bifacial installations with single-axis trackers reach the lowest LCOE almost everywhere (i.e., 93.1% of the total land area), while their monofacial counterparts achieve the lowest LCOE in only 3.1% of the land area. In addition, bifacial two-axis tracker installations reach the lowest LCOE only for remote areas very close to the poles, at latitudes beyond 70°, accounting for 3.8% of the total land area. Furthermore, monofacial single-axis trackers achieve the second lowest LCOE values for 87.9% of the land area.
  • On the one hand, these findings are explained by the fact that one-axis tracker systems generate comparably high yields (Figure 9), while requiring only marginally higher cost (Figure 10) compared with fixed-tilt installations. On the other hand, although two-axis tracker systems in general generate the highest yield, their considerably more expensive mounting structure (see Figures 7 and 10) outweighs the benefits in energy generation.
  • In addition, Figure 11 also reveals that, compared with conventional fixed-tilt installations, bifacial fixed-tilt installations feature higher LCOE values close to the equator (compare Figures 11A and 11B), whereas tracker installations with bifacial modules reach, in general, lower LCOE values compared with their monofacial counterparts (compare Figures 11C–11F).

The full report is here.

Source: CleanTechnica

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