Agrivoltaic system achieves 9.9% efficiency, LCOE of $0.033/kWh

Researchers in China have built a prototype of a spectral-splitting concentrator agrivoltaic system (SCAPV) with a PV efficiency of 9.9, a hybrid light-use efficiency rating of 9.05%, and a levelized cost of energy (LCOE) of $0.033/kWh.

SCAPV system

Image: University of Science and Technology of China

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Scientists led by the University of Science and Technology of China have developed a spectral-splitting concentrator agrivoltaic (SCAPV) system that can reportedly increase the crop productivity of multiple plant species.

The SCAPV system is based on the spectral separation of sunlight based on the difference in the spectral response of photovoltaics and photosynthesis. According to this principle, red and blue wavelengths are used for photosynthesis as they match the absorption peaks of plant chlorophyll, while all other wavelengths are used for concentrated power generation.

The research group described their findings in “Spectral-splitting concentrator agrivoltaics for higher hybrid solar energy conversion efficiency” which was recently published in Energy Conversion and Management. They highlighted the system’s key components: multilayer polymer films (MPFs) enabling spectral separation, parabolic trough concentrators (PTCs), and crystalline silicon solar cells.

They used commercially available MPFs with high transmittance manufactured by US-based industrial conglomerate 3M. The PTCs are used as a substrate for the flexible MPFs and as reflectors to direct the reflected bands toward focal-point interdigitated back contact (IBC) PV cells, which were provided by US-based manufacturer Sunpower.

“Although multijunction III-V cells hold potential for higher efficiency, silicon cells are cost competitive for a scalable solution, and can maintain performance under high incident radiation within a concentration ratio of 3–100,” they further explained, noting that each PV module includes a front cover made of low-iron glass, a backsheet made of ethylene vinyl acetate (EVA), and a back aluminum substrate.

The researchers said the PV cells and MPFs had a cost of $0.10/W and $0.02/W, respectively, while the hardware including the concentrators and the trackers cost $0.57/W.

The group tested the performance of the system through a prototype deployed in Fuyang, in China’s Anhui province. This system occupies a surface of 422.4 square meters and relies on a dual-axis solar tracking system.

The system was found to have a PV efficiency of 9.9% and a hybrid light use efficiency of 9.05%, which the academics said is higher than the maximal theoretical photosynthetic efficiency of around 6%.

“The economic analysis shows that the LCOE of SCAPV is 0.033 $/kWh, indicating its economic feasibility,” they said, adding that the plants grown under partial sunlight showed the potential for increased biomass. “Although these tunable PVs are usually not cost competitive for now, agrivoltaics provide a niche market where they can provide advantages over conventional silicon photovoltaics and hence have the opportunity to be commercialized and improved.”

The research group unveiled its basic SCAPV system design in October. That system was tested in outdoor conditions in Anhui, and was found able to produce 107 MWh of electricity per hectare. Its overall system efficiency reached 11.6%, which the scientists said is the highest efficiency ever recorded for the spectral separation technology.

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