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.
“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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The innovative approach presented in this research article explores the intersection of agrivoltaics and spectral-splitting concentrators, introducing a unique dimension to energy conversion efficiency. While the reported metrics of a 9.9% PV efficiency and a hybrid light use efficiency of 9.05% are noteworthy, it’s crucial to clarify that the discussed Levelized Cost of Electricity (LCOE) of $0.033/kWh doesn’t align with the conventional understanding of LCOE in the energy sector.
In the traditional sense, LCOE predominantly refers to the cost of generating electricity over a project’s lifetime. However, the authors ingeniously adapt this metric translating the LCOE to LCE, Levelized Cost of Energy to reflect this hybrid production between the solar one and the potential electrical cost equivalent to dry biomass production. This adaptation brings an interesting scientific perspective but deviates from the financial aspect intrinsic to the typical LCOE calculation in the energy industry because the Levelized cost of electricity (LCOE) is defined as the price at which the generated electricity should be sold for the system to break even at the end of its lifetime. At the moment what they are saying is that you link a real production of electricity (solar) to a possible saving of electricity for the production of biomass.
It’s noteworthy that the research team’s work provides valuable insights into the complex interplay of spectral separation, photosynthesis, and power generation. However, the discussion around cost breakdowns, including PV cells, multilayer polymer films, and hardware, doesn’t add much transparency to the economic considerations of implementing such systems because following the data that they have for 1MWp an initial capital cost of only 1’880’000$ that could be comparable to a normal agrivoltaic plant nowadays.